Glomerulonephritis

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Overview

Definition

Glomerulonephritis (GN) refers to a group of kidney diseases characterized by inflammation of the glomeruli, the tiny filters within the kidneys responsible for filtering waste products and excess water from the blood. This inflammation can lead to damage to the glomerular basement membrane, mesangial cells, and/or podocytes, impairing kidney function and potentially leading to kidney failure.

Epidemiology

The epidemiology of GN varies significantly by type: * IgA Nephropathy (IgAN): Most common primary GN worldwide, particularly prevalent in Asia and among Caucasians. Incidence varies geographically, affecting 2.5-10 per 100,000 person-years. More common in males. * Post-infectious Glomerulonephritis (PIGN): Primarily affects children (5-15 years old) following streptococcal infections, but can occur at any age. Incidence has decreased in developed countries due to antibiotic use. * Membranous Nephropathy (MN): Most common cause of nephrotic syndrome in adults, with an incidence of about 1-2 per 100,000 per year. * Focal Segmental Glomerulosclerosis (FSGS): Incidence has increased in recent decades, now a leading cause of nephrotic syndrome in adults and children, particularly in African Americans. * Lupus Nephritis: Occurs in up to 60% of patients with Systemic Lupus Erythematosus (SLE), more common in women and individuals of African, Hispanic, and Asian descent. * Rapidly Progressive Glomerulonephritis (RPGN): Rare but severe, with an annual incidence of 2-7 per million population, often affecting older adults.

Classification

Glomerulonephritis is classified based on several factors, including clinical presentation, pathology, and etiology:

1. Based on Clinical Presentation: * Nephritic Syndrome: Characterized by hematuria (often macroscopic and "cola-colored"), proteinuria (typically non-nephrotic, <3.5 g/day), hypertension, edema, and acute kidney injury (AKI). * Nephrotic Syndrome: Characterized by heavy proteinuria (≥3.5 g/day or urine protein-to-creatinine ratio >300 mg/mmol or >3 g/g), hypoalbuminemia (<30 g/L), severe edema, and hyperlipidemia. * Asymptomatic Urinary Abnormalities: Isolated microscopic hematuria and/or proteinuria. * Rapidly Progressive Glomerulonephritis (RPGN): Rapid decline in kidney function (≥50% loss of GFR within 3 months), often accompanied by nephritic features, and characterized by extensive crescent formation on biopsy.

2. Based on Etiology: * Primary Glomerulonephritis: Disease primarily affecting the kidney, with no identifiable systemic cause. * IgA Nephropathy (IgAN) * Membranous Nephropathy (MN) * Focal Segmental Glomerulosclerosis (FSGS) * Minimal Change Disease (MCD) * Post-infectious Glomerulonephritis (PIGN) * Membranoproliferative Glomerulonephritis (MPGN, now often reclassified based on underlying cause) * Secondary Glomerulonephritis: Occurs as part of a systemic disease. * Lupus Nephritis (Systemic Lupus Erythematosus) * Diabetic Nephropathy (often considered a separate entity, but involves glomerular changes) * ANCA-associated Vasculitis (Granulomatosis with polyangiitis, Microscopic polyangiitis, Eosinophilic granulomatosis with polyangiitis) * Anti-Glomerular Basement Membrane (Anti-GBM) Disease (Goodpasture's Syndrome) * Cryoglobulinemic Vasculitis (often associated with Hepatitis C) * Amyloidosis (can affect glomeruli) * Henoch-Schönlein Purpura (IgA vasculitis) * Thrombotic Microangiopathies (e.g., HUS, TTP) * HIV-associated Nephropathy (HIVAN)

Pathophysiology

Mechanism

Glomerulonephritis is fundamentally an immune-mediated inflammatory process targeting the glomeruli. The underlying mechanisms vary by type:

1. Immune Complex Deposition:

   • In situ formation: Antibodies react with antigens within the glomerulus (e.g., planted antigens, endogenous glomerular antigens). This leads to immune complex formation and activation of complement cascade, attracting inflammatory cells. Examples: Membranous Nephropathy (antibodies to PLA2R), anti-GBM disease.
   • Circulating immune complex deposition: Immune complexes formed in the circulation deposit in the glomeruli. This often occurs when there's an excess of antigen or impaired clearance of immune complexes. Examples: Post-infectious GN (streptococcal antigens), Lupus Nephritis (DNA-anti-DNA complexes), IgA Nephropathy (abnormal IgA1 complexes). These immune complexes activate the complement system (classical or alternative pathways), leading to the generation of anaphylatoxins (C3a, C5a) and membrane attack complex (MAC, C5b-9). This causes:
   • Chemotaxis of neutrophils and monocytes.
   • Release of proteases and reactive oxygen species, damaging glomerular cells (endothelial, mesangial, podocytes) and the glomerular basement membrane (GBM).
   • Proliferation of mesangial and endothelial cells, leading to glomerular hypercellularity.
   • Increased permeability of the GBM, leading to proteinuria and hematuria.

2. Direct Antibody-Mediated Injury:

   • Antibodies directly bind to components of the glomerular basement membrane (e.g., in anti-GBM disease, antibodies target the non-collagenous domain of type IV collagen). This leads to rapid complement activation and severe inflammation, often resulting in crescentic GN.

3. Cell-Mediated Immunity:

   • T-lymphocytes and macrophages can infiltrate the glomeruli, releasing cytokines and chemokines that contribute to inflammation and tissue damage. This is particularly relevant in some forms of RPGN and chronic progressive GNs.

4. Podocyte Injury:

   • In diseases causing nephrotic syndrome (e.g., Minimal Change Disease, FSGS), direct injury to podocytes (visceral epithelial cells) leads to effacement of foot processes, disruption of the slit diaphragm, and loss of the filtration barrier's anionic charge. This results in massive proteinuria without significant inflammation. The precise mechanisms of podocyte injury can involve circulating factors, genetic mutations, or immune dysregulation.

Risk Factors

• Infections: Streptococcal pharyngitis/skin infection (PIGN), Hepatitis B/C (MPGN, cryoglobulinemia), HIV (HIVAN), endocarditis, shunt infections.
• Autoimmune Diseases: Systemic Lupus Erythematosus (Lupus Nephritis), ANCA-associated vasculitis, rheumatoid arthritis, Sjögren's syndrome.
• Genetic Factors: Family history of IgAN, specific HLA alleles, certain mutations for FSGS (e.g., NPHS2, TRPC6).
• Medications: NSAIDs (can exacerbate kidney disease), certain antibiotics (e.g., rifampicin can cause immune complex GN), gold salts (MN).
• Environmental Factors: Exposure to certain solvents (hydrocarbons) and silica has been linked to ANCA vasculitis.
• Demographic Factors: Age (children for PIGN and MCD, older adults for MN, RPGN), ethnicity (IgAN in Asians/Caucasians, FSGS in African Americans, Lupus Nephritis in non-Caucasians).
• Other Kidney Diseases: Chronic kidney disease from any cause can alter glomerular hemodynamics and potentially accelerate progression.

Protective Factors

Specific "protective factors" against the development of GN are limited, as most primary GNs are idiopathic or immune-mediated. However, general health measures and early intervention can mitigate risks and progression: * Prompt Treatment of Infections: Especially streptococcal infections, to prevent PIGN. * Control of Underlying Systemic Diseases: Effective management of SLE, vasculitis, and other autoimmune conditions can prevent or mitigate secondary GN. * Vaccinations: Immunization against infectious agents like influenza and pneumococcus can reduce the risk of infections that may trigger GN or complicate immunosuppressive therapy. * Avoidance of Nephrotoxic Agents: Prudent use of NSAIDs and other potentially harmful drugs, especially in at-risk individuals. * Genetic Counseling: For families with known genetic predispositions to specific GNs (e.g., FSGS), though direct prevention is often not possible. * Healthy Lifestyle: General cardiovascular health (blood pressure control, healthy diet, exercise) supports overall kidney health and may slow progression of established kidney disease.

Clinical Presentation

Signs and Symptoms

Cardinal Features

The clinical presentation of GN is highly variable, ranging from asymptomatic urinary abnormalities to rapidly progressive kidney failure. * Hematuria: Blood in the urine. * Microscopic: Detected only by urinalysis; often asymptomatic. * Macroscopic (Gross): Visible to the naked eye, often described as "cola-colored," "smoky," or "tea-colored." Indicates active glomerular bleeding. * Proteinuria: Excess protein in the urine. * Nephritic range: Typically <3.5 g/day, often accompanied by hematuria. * Nephrotic range: ≥3.5 g/day, leading to hypoalbuminemia and edema. * Edema: Swelling, initially often periorbital (around the eyes) and then peripheral (ankles, legs), or generalized (anasarca) in severe cases. Due to fluid retention (nephritic) or hypoalbuminemia (nephrotic). * Hypertension: Elevated blood pressure, often due to fluid overload and activation of the renin-angiotensin-aldosterone system. Can be severe and contribute to cardiovascular complications. * Reduced Urine Output (Oliguria/Anuria): Indicates significant decline in kidney function and can be an early sign of AKI. * Fatigue, Malaise, Weakness: Non-specific symptoms common with chronic illness and anemia of chronic kidney disease.

Early Signs

• Microscopic hematuria: Often the earliest sign, detected incidentally on routine urinalysis.
• Mild proteinuria: May be discovered incidentally.
• Subtle edema: Especially periorbital edema upon waking, or mild ankle swelling.
• Mild hypertension: May be initially asymptomatic.
• Nonspecific systemic symptoms: Fatigue, headache, mild nausea if associated with a systemic disease.
• Recent infection: For PIGN, history of streptococcal pharyngitis (1-3 weeks prior) or skin infection (3-6 weeks prior).

Advanced Signs

• Severe Edema/Anasarca: Generalized body swelling, ascites, pleural effusions, pulmonary edema.
• Severe Hypertension: Potentially leading to hypertensive encephalopathy, retinopathy, or cardiac complications.
• Oliguria/Anuria: Very low or no urine output, indicating severe acute kidney injury.
• Symptoms of Uremia: Due to accumulation of nitrogenous waste products:
  • Nausea, vomiting, anorexia
  • Pruritus (itching)
  • Altered mental status (confusion, lethargy, seizures)
  • Pericarditis, pleuritis
  • Asterixis (flapping tremor)
• Signs of Fluid Overload: Dyspnea (shortness of breath), orthopnea, paroxysmal nocturnal dyspnea, crackles on lung auscultation.
• Signs of Systemic Disease: Rashes, arthralgia/arthritis, oral ulcers, fever, weight loss, lymphadenopathy if secondary to SLE or vasculitis.

Atypical Presentations

• Isolated asymptomatic microscopic hematuria: With normal renal function and no proteinuria, may be the sole manifestation (e.g., thin basement membrane disease, early IgAN).
• Isolated proteinuria: Without hematuria or other symptoms, often seen in early stages of some nephrotic syndromes or even FSGS.
• Rapidly Progressive Glomerulonephritis (RPGN): Can present acutely with a rapid decline in kidney function over days to weeks, often with severe nephritic features but minimal prior symptoms. May initially be mistaken for acute tubular necrosis.
• Flu-like illness: Some forms of vasculitis (e.g., ANCA-associated) can begin with non-specific systemic symptoms before overt kidney involvement.

Physical Examination

Inspection

• Edema: Periorbital, facial, sacral, peripheral (pitting edema of ankles/shins), or generalized anasarca. Ascites, pleural effusions (causing decreased breath sounds, dullness to percussion).
• Skin: Pallor (anemia), rashes (e.g., malar rash in SLE, palpable purpura in vasculitis or Henoch-Schönlein Purpura, livedo reticularis), petechiae.
• General appearance: Evidence of chronic illness, fatigue, signs of malnutrition (in severe nephrotic syndrome).
• Eyes: Funduscopic examination for hypertensive retinopathy (arteriolar narrowing, hemorrhages, exudates, papilledema).
• Neck veins: Jugular venous distension (JVD) indicating fluid overload/increased central venous pressure.

Palpation

• Edema: Assess for pitting edema severity.
• Cardiac: Displaced apical impulse (cardiomegaly), thrills, heaves.
• Abdomen: Tenderness, hepatomegaly (due to congestion), ascites (fluid wave, shifting dullness).
• Peripheral pulses: Assess for strength and symmetry.
• Joints: Swelling, tenderness, warmth in cases of systemic rheumatological disease.
• Lymph nodes: Lymphadenopathy in systemic conditions.

Special Tests

• Blood Pressure Measurement: Crucial for all patients. Hypertension is a hallmark.
• Cardiac Auscultation: Murmurs (valvular heart disease), gallop rhythm (S3, S4, indicating heart failure), pericardial rub (uremic pericarditis).
• Pulmonary Auscultation: Crackles/rales (pulmonary edema), diminished breath sounds (pleural effusions).
• Neurological Examination: Assess for altered mental status, asterixis, and focal neurological deficits if vasculitis or severe uremia is present.
• Fundoscopy: To evaluate for hypertensive retinopathy or papilledema.

Diagnostic Approach

History Taking

Key Questions

• Onset and Duration: When did symptoms start? Acute, subacute, or chronic?
• Urinary Symptoms:
  • Presence of gross hematuria (color, timing - initial, terminal, total), dysuria, frequency, nocturia.
  • Changes in urine output (oliguria, anuria).
  • Frothy urine (suggestive of heavy proteinuria).
• Edema: Location, timing (worse in morning/evening), progression.
• Blood Pressure: History of hypertension, current medications.
• Systemic Symptoms:
  • Fever, chills, night sweats, fatigue, malaise, weight loss.
  • Rash, joint pain (arthralgia/arthritis), oral ulcers, photosensitivity (SLE).
  • Upper respiratory symptoms (sinusitis, epistaxis), hemoptysis (vasculitis, anti-GBM disease).
  • Neurological symptoms (headaches, seizures, altered mental status).
  • Gastrointestinal symptoms (nausea, vomiting, abdominal pain).
• Past Medical History:
  • Recent infections (strep throat, skin infection, flu-like illness, hepatitis, HIV).
  • Autoimmune diseases (SLE, rheumatoid arthritis).
  • Diabetes mellitus, malignancy.
  • Previous kidney disease or urinary abnormalities.
• Medication History: NSAIDs, antibiotics, gold, penicillamine, illicit drugs.
• Family History: Kidney disease, autoimmune conditions, deafness (Alport syndrome).
• Social History: Smoking, alcohol, illicit drug use.
• Travel History: Exposure to endemic infectious diseases.

Red Flags

• Rapid decline in urine output or sudden onset of anuria.
• Rapidly worsening kidney function (creatinine doubling in days/weeks).
• Severe uncontrolled hypertension with end-organ damage (e.g., neurological changes, vision changes).
• Symptoms of fluid overload: Acute dyspnea, orthopnea, worsening edema, signs of pulmonary edema.
• Signs of severe systemic disease: Hemoptysis (pulmonary-renal syndrome), severe abdominal pain, new-onset neurological deficits, widespread vasculitic rash.
• Hyperkalemia or severe acidosis: Indicating urgent need for intervention.

Laboratory Tests

First-Line

• Urinalysis with Microscopy:
  • Hematuria: Presence of red blood cells. Dysmorphic RBCs and RBC casts are highly suggestive of glomerular origin.
  • Proteinuria: Detected by dipstick (semi-quantitative).
  • Leukocyturia: White blood cells, may indicate inflammation or infection.
  • Casts: Granular casts, waxy casts (indicate chronic kidney disease).
• Urine Protein Quantification:
  • Urine protein-to-creatinine ratio (UPCR): Preferred screening, single spot urine sample. Normal <150-200 mg/g. Nephrotic range >3.5 g/g.
  • 24-hour urine protein collection: Gold standard for exact quantification, though less convenient. Normal <150 mg/24h.
• Serum Creatinine and Blood Urea Nitrogen (BUN): To assess kidney function and estimate GFR. Monitor trends.
• Electrolytes: Sodium, potassium, bicarbonate (for acid-base status).
• Complete Blood Count (CBC): Anemia (chronic disease, blood loss), leukocytosis (infection, inflammation).
• Erythrocyte Sedimentation Rate (ESR) and C-reactive protein (CRP): Non-specific markers of inflammation, often elevated in active GN and systemic disease.
• Serum Albumin: Often low in nephrotic syndrome due to urinary loss.
• Complement Levels (C3, C4):
  • Low C3 and/or C4 suggests activation of complement, common in Lupus Nephritis, PIGN (C3 low), Cryoglobulinemic GN (C4 low), MPGN.
  • Normal C3/C4 is common in IgAN, ANCA vasculitis, Anti-GBM disease, MN, FSGS, MCD.

Confirmatory

• Renal Biopsy: Gold standard for definitive diagnosis, classification, assessment of severity, activity, and chronicity. Crucial for guiding treatment decisions and prognosis. Histological findings determine specific GN type.
• Serological Markers (based on clinical suspicion):
  • Antinuclear Antibodies (ANA) and anti-dsDNA: For Systemic Lupus Erythematosus (SLE).
  • Antineutrophil Cytoplasmic Antibodies (ANCA):
    • c-ANCA (anti-PR3): Granulomatosis with polyangiitis (GPA).
    • p-ANCA (anti-MPO): Microscopic polyangiitis (MPA), Eosinophilic granulomatosis with polyangiitis (EGPA).
  • Anti-Glomerular Basement Membrane (Anti-GBM) antibodies: For Anti-GBM disease (Goodpasture's syndrome).
  • Anti-streptolysin O (ASO) titer/Anti-DNase B: For recent streptococcal infection (Post-infectious GN).
  • Hepatitis B and C serology: To rule out viral-associated GNs (e.g., MPGN, cryoglobulinemic vasculitis).
  • HIV serology: To rule out HIV-associated nephropathy.
  • Cryoglobulins: For cryoglobulinemic vasculitis.
  • Serum Protein Electrophoresis (SPEP) and Urine Protein Electrophoresis (UPEP) with immunofixation: To rule out monoclonal gammopathy (e.g., light chain deposition disease, amyloidosis, cryoglobulinemia).
  • Anti-Phospholipase A2 Receptor (PLA2R) antibodies: Highly specific for primary Membranous Nephropathy.
  • Thrombotic Microangiopathy workup: ADAMTS13 activity (TTP), Shiga toxin (HUS).

Monitoring

• Serum Creatinine, eGFR, BUN: Regularly to track kidney function.
• Urine protein-to-creatinine ratio (UPCR): To monitor proteinuria response to treatment.
• Blood Pressure: Regular home and clinic measurements.
• Electrolytes: Monitor for imbalances, especially with diuretics or ACEi/ARBs.
• CBC: Monitor for anemia, and for leukopenia/thrombocytopenia if on immunosuppressants.
• Liver Function Tests (LFTs): For drug toxicity, or baseline if Hepatitis B/C is a factor.
• Glucose and Lipid Profile: Important for cardiovascular risk assessment and for steroid-induced diabetes/dyslipidemia.
• Specific Serological Markers: Repeat ANCA, ANA, anti-dsDNA, C3/C4 to monitor disease activity in systemic GNs.
• Drug Levels: If on calcineurin inhibitors (cyclosporine, tacrolimus) or mycophenolate mofetil (MMF).

Imaging

Recommended

• Renal Ultrasound with Doppler:
  • Kidney size and echogenicity: Small, scarred kidneys indicate chronic disease. Normal or enlarged kidneys are typical in acute GN. Increased echogenicity can suggest inflammation or fibrosis.
  • Corticomedullary differentiation: Loss suggests chronicity.
  • Hydronephrosis/obstruction: Rule out post-renal causes of AKI.
  • Vascular flow: Doppler helps assess renal artery stenosis (though less common cause of GN itself).

Advanced

• CT Angiography or MR Angiography:
  • If renal artery stenosis or vasculitis affecting larger renal vessels is suspected.
  • To evaluate for aneurysms in polyarteritis nodosa.
• Chest X-ray or CT Chest:
  • If pulmonary involvement is suspected (e.g., pulmonary edema in fluid overload, hemorrhage in pulmonary-renal syndromes like anti-GBM disease or ANCA vasculitis).
• Echocardiogram:
  • To assess for cardiac complications like pericardial effusion (uremia), heart failure (fluid overload, hypertension), or infective endocarditis.

Management

Management of GN is highly specific to the underlying histological diagnosis and clinical presentation. The following outlines general principles and common interventions. Renal biopsy is crucial to guide specific immunosuppressive therapy.

Acute Management

Immediate

• Address Life-Threatening Complications:
  • Severe Hypertension (Hypertensive Emergency): IV anti-hypertensives (e.g., IV labetalol, nicardipine, clevidipine) to rapidly reduce blood pressure without causing hypoperfusion. Target organ damage (e.g., encephalopathy, pulmonary edema) dictates urgency.
  • Acute Pulmonary Edema: Diuretics (IV furosemide 40-100 mg initially, escalate as needed), oxygen, sometimes non-invasive positive pressure ventilation (NIPPV) or mechanical ventilation.
  • Severe Hyperkalemia (K+ >6.5 mEq/L or with ECG changes): IV calcium gluconate (cardioprotection), IV insulin/glucose, beta-agonists, sodium bicarbonate, potassium binders. Urgent dialysis if refractory.
  • Severe Acidosis (pH <7.1): Sodium bicarbonate infusion. Urgent dialysis if refractory.
  • Uremic Pericarditis/Encephalopathy: Urgent hemodialysis.

Stabilization

• Fluid and Electrolyte Management: Adjust fluid intake based on urine output and volume status. Correct electrolyte imbalances.
• Initiate Empiric Therapy (if RPGN suspected): If there's a rapid decline in kidney function and strong suspicion of RPGN (e.g., rapidly progressive nephritic syndrome with crescent formation likely on biopsy or serological evidence of ANCA/anti-GBM), empiric high-dose corticosteroids (e.g., IV methylprednisolone 500-1000 mg daily for 3 days) may be started before definitive biopsy results, to preserve kidney function.
• Renal Replacement Therapy (RRT): Initiate hemodialysis or peritoneal dialysis for severe AKI, uremia, refractory fluid overload, hyperkalemia, or acidosis.

Emergency

• Plasmapheresis: Indicated for severe Anti-GBM disease (especially with lung hemorrhage), severe ANCA-associated vasculitis with rapidly progressive kidney failure (creatinine >5.6 mg/dL or need for dialysis) or diffuse alveolar hemorrhage, and sometimes for severe cryoglobulinemic vasculitis.
  • Regimen: Typically 7-10 exchanges over 1-2 weeks, removing plasma and replacing it with albumin (or fresh frozen plasma if significant bleeding risk).
• Urgent Renal Biopsy: To establish a definitive diagnosis, particularly in RPGN, to guide specific immunosuppressive therapy.

Chronic Management

Pharmacological

1. Immunosuppressive Therapy: Specific regimen depends on GN type, severity, and chronicity. * Corticosteroids (e.g., Prednisone, Methylprednisolone): Cornerstone for many GNs. * High-dose oral prednisone: 0.5-1 mg/kg/day (max 60-80 mg/day) for induction, then tapered over months. * IV methylprednisolone pulse: 500-1000 mg/day for 3 days for severe inflammation (RPGN, severe lupus nephritis). * Cyclophosphamide: Potent alkylating agent, often used in conjunction with corticosteroids for severe proliferative GNs (e.g., ANCA vasculitis, severe lupus nephritis, anti-GBM disease). * IV pulse: 0.5-1 g/m² body surface area monthly for 3-6 months. * Oral: 1.5-2 mg/kg/day. * Side effects: Myelosuppression, hemorrhagic cystitis (mesna co-administration), infertility, malignancy. * Mycophenolate Mofetil (MMF) / Mycophenolic Acid (MPA): Antiproliferative agent, often used for induction and maintenance in lupus nephritis, and increasingly in IgAN, FSGS. * Dosage: 1-1.5 g twice daily. * Side effects: GI upset, myelosuppression, infections. * Calcineurin Inhibitors (CNIs - Cyclosporine, Tacrolimus): Used in nephrotic syndrome (MCD, FSGS, MN) and lupus nephritis. * Dosage: Cyclosporine 2-4 mg/kg/day in 2 divided doses; Tacrolimus 0.05-0.1 mg/kg/day in 2 divided doses (target trough levels). * Side effects: Nephrotoxicity (vasoconstriction, interstitial fibrosis), hypertension, neurotoxicity, hyperkalemia, gingival hyperplasia (cyclosporine), diabetes (tacrolimus). * Rituximab: Chimeric monoclonal antibody targeting CD20 B-lymphocytes. Used in MN (PLA2R-positive), ANCA vasculitis, refractory lupus nephritis, and some forms of FSGS. * Dosage: Varies; e.g., 375 mg/m² weekly for 4 doses, or 1000 mg on day 1 and day 15, repeated as needed. * Side effects: Infusion reactions, infections (PML rare). * Azathioprine: Used for maintenance therapy in lupus nephritis, ANCA vasculitis, and sometimes IgAN. * Dosage: 1-2 mg/kg/day. * Side effects: Myelosuppression, hepatotoxicity, pancreatitis. * Other Immunosuppressants: Dapsone (for IgAN with cutaneous vasculitis), IVIG (for refractory cases).

2. Supportive Therapies: * Angiotensin-Converting Enzyme (ACE) Inhibitors or Angiotensin Receptor Blockers (ARBs): First-line for blood pressure control and reduction of proteinuria in most GNs, especially if UPCR >0.5 g/g. * Dosage: Titrate to achieve target BP and proteinuria reduction. Start low and increase slowly. * Side effects: Hyperkalemia, cough (ACEi), acute kidney injury (monitor creatinine within 1-2 weeks of initiation/dose change). * Diuretics: For edema and fluid overload (loop diuretics like furosemide, thiazides for mild edema). * Statins: For hyperlipidemia, especially in nephrotic syndrome (to reduce cardiovascular risk). * Dosage: As per cardiovascular guidelines (e.g., atorvastatin 20-80 mg daily). * Anticoagulation: Consider in severe nephrotic syndrome (serum albumin <20-25 g/L) due to high risk of thromboembolism, particularly in membranous nephropathy. Prophylactic anticoagulation (e.g., warfarin, DOACs) may be considered, but individualized risk assessment is crucial. * Sodium Glucose Co-transporter 2 (SGLT2) Inhibitors: Emerging role in reducing proteinuria and slowing CKD progression in various GNs, even in non-diabetic patients, due to their renoprotective effects. * Dosage: Dapagliflozin 10 mg daily or empagliflozin 10 mg daily, if eGFR >20-25 mL/min/1.73m². * Side effects: Genital mycotic infections, euglycemic DKA (rare).

Non-pharmacological

• Dietary Modifications:
  • Sodium Restriction: <2 g/day for hypertension and edema.
  • Fluid Restriction: For severe edema or hyponatremia.
  • Protein Restriction: Usually not recommended for early GN, but may be considered for advanced CKD (0.6-0.8 g/kg/day) to reduce uremic symptoms.
  • Potassium/Phosphate Restriction: If hyperkalemia or hyperphosphatemia develop in advanced CKD.
• Blood Pressure Monitoring: Regular home blood pressure measurements. Target BP <130/80 mmHg (or often <120/80 mmHg for patients with high proteinuria).
• Smoking Cessation: Crucial for overall cardiovascular and kidney health.
• Exercise and Weight Management: To reduce cardiovascular risk and improve general well-being.
• Infection Prophylaxis: Immunizations (influenza, pneumococcal, hepatitis B), especially if on immunosuppression. Prophylactic antibiotics (e.g., TMP/SMX for PCP) if on high-dose steroids or cyclophosphamide.

Monitoring

• Regular Blood and Urine Tests: Serum creatinine, eGFR, electrolytes, UPCR (or 24h urine protein), CBC, LFTs.
• Blood Pressure: At every clinic visit and home monitoring.
• Medication Side Effects: Monitor for infections, myelosuppression, hepatotoxicity, nephrotoxicity, diabetes, dyslipidemia, osteopenia.
• Disease Activity: Clinical symptoms, serological markers (ANA, ANCA, complement levels), and proteinuria.
• Complications: Screening for cardiovascular disease, bone disease, anemia.

Treatment Algorithms

Treatment algorithms are highly disease-specific. Below is a generalized framework emphasizing common GNs.

First-Line (Examples)

• Minimal Change Disease (MCD): Oral corticosteroids (prednisone 1 mg/kg/day or 60 mg/day for adults for 4-16 weeks, then taper).
• Focal Segmental Glomerulosclerosis (FSGS) - Primary: Oral corticosteroids (prednisone 1 mg/kg/day or 60 mg/day for 3-6 months, then taper). If steroid-resistant, CNI (cyclosporine or tacrolimus).
• Membranous Nephropathy (MN) - Primary:
  • Low risk: Supportive care (ACEi/ARB, statin, BP control).
  • Moderate/High risk (proteinuria >4-8 g/day, declining GFR, or severe symptoms): Immunosuppression (modified Ponticelli regimen: alternating cycles of oral corticosteroids + cyclophosphamide OR rituximab OR CNI). Anti-PLA2R antibody levels guide therapy and monitoring.
• IgA Nephropathy (IgAN):
  • Supportive care for all: ACEi/ARB for proteinuria (>0.5-1 g/day) and BP control (target <120/80 mmHg). SGLT2 inhibitors.
  • High risk (persistent proteinuria >1 g/day despite 3-6 months of supportive care, GFR >30 mL/min/1.73m²): Oral corticosteroids (e.g., prednisone 0.5 mg/kg/day for 6-9 months). Budesonide modified release (e.g., Nefecon) for gut-specific IgAN.
• Post-infectious GN (PIGN): Supportive care (BP control, diuretics, fluid restriction, antibiotics for ongoing infection). Immunosuppression generally not indicated.
• Lupus Nephritis (Classes III/IV/V):
  • Induction: High-dose corticosteroids (e.g., IV methylprednisolone 500-1000 mg for 3 days, then oral prednisone 0.5-1 mg/kg/day) + Mycophenolate Mofetil (MMF 1-1.5 g BID) OR IV Cyclophosphamide (NIH or Euro-Lupus regimen).
  • Maintenance: MMF (0.5-1.5 g BID) or Azathioprine (1.5-2 mg/kg/day) for several years.
• ANCA-associated Vasculitis / Anti-GBM Disease (RPGN):
  • Induction: High-dose corticosteroids (IV methylprednisolone pulse, then oral prednisone) + Cyclophosphamide (IV pulse or oral) OR Rituximab.
  • Plasmapheresis: For severe kidney disease (creatinine >5.6 mg/dL or dialysis dependency) and/or pulmonary hemorrhage in ANCA vasculitis, and for all Anti-GBM disease.
  • Maintenance: Azathioprine or MMF or Rituximab.

Second-Line (Examples)

• Steroid-resistant MCD/FSGS: CNIs (cyclosporine/tacrolimus), MMF, cyclophosphamide, rituximab.
• Refractory MN: Rituximab, CNIs, second course of cyclophosphamide.
• Refractory IgAN: MMF, CNIs, tonsillectomy (controversial, more common in Asia).
• Refractory Lupus Nephritis: Rituximab, belimumab, voclosporin (new CNI for LN), different immunosuppression combinations.
• Refractory ANCA/Anti-GBM: Switch immunosuppressant (e.g., cyclophosphamide to rituximab), increase dose/duration of current therapy, consider IVIG.

Refractory Cases

• Re-biopsy: Consider if there is persistent or worsening disease despite adequate treatment to assess for progression, chronicity, or a different diagnosis.
• Clinical Trials: Enrollment in trials for novel therapies.
• Increased Immunosuppression: Intensified regimens, but balancing efficacy with increased risk of side effects.
• Supportive Care & Preparation for ESRD: If kidney function continues to decline despite maximal therapy, focus shifts to managing CKD complications and preparing for renal replacement therapy (dialysis or transplantation).

Complications

Common

• Hypertension: Can be severe and contribute to cardiovascular disease.
• Edema: From fluid retention and/or hypoalbuminemia.
• Acute Kidney Injury (AKI): Rapid decline in renal function.
• Chronic Kidney Disease (CKD): Progressive, irreversible loss of kidney function.
• Proteinuria/Nephrotic Syndrome-related:
  • Hyperlipidemia: Due to increased hepatic lipoprotein synthesis.
  • Increased susceptibility to infection: Due to loss of immunoglobulins in urine and/or immunosuppressive therapy.
  • Thromboembolism: Particularly in nephrotic syndrome, due to loss of anticoagulant proteins (e.g., antithrombin III) and increased procoagulant factors. Renal vein thrombosis is a known risk.
• Anemia: Anemia of chronic disease, or due to blood loss if severe hematuria.
• Electrolyte Imbalances: Hyperkalemia, hyperphosphatemia, metabolic acidosis.
• Complications of Immunosuppression: Increased risk of infections (bacterial, viral, fungal, opportunistic), malignancy, hypertension, diabetes, osteoporosis, avascular necrosis, gastrointestinal side effects, myelosuppression.

Serious

• End-Stage Renal Disease (ESRD): Requiring dialysis or kidney transplantation.
• Hypertensive Crisis: Leading to stroke, acute heart failure, or other end-organ damage.
• Pulmonary Edema: Life-threatening fluid overload in the lungs.
• Uremic Pericarditis/Encephalopathy: Indications for urgent dialysis.
• Sepsis: A severe systemic infection, especially in immunosuppressed patients.
• Thrombotic events: Deep vein thrombosis (DVT), pulmonary embolism (PE), renal vein thrombosis.
• Pulmonary-renal syndrome: Concomitant lung hemorrhage and severe GN (e.g., anti-GBM disease, ANCA vasculitis).
• Malignancy: Long-term risk with certain immunosuppressants (e.g., cyclophosphamide, azathioprine).

Long-term

• Chronic Kidney Disease (CKD) Progression: Irreversible decline in GFR, ultimately leading to ESRD in many cases.
• Cardiovascular Disease: Hypertension, dyslipidemia, inflammation contribute to accelerated atherosclerosis. A leading cause of morbidity and mortality in CKD.
• Bone and Mineral Disorders (CKD-MBD): Renal osteodystrophy, hyperparathyroidism, hyperphosphatemia.
• Anemia of Chronic Kidney Disease: Requires management with erythropoiesis-stimulating agents (ESAs) or iron supplementation.
• Increased risk of infection: Due to ongoing immunosuppression and impaired immune function in CKD.
• Drug-related toxicities: Long-term side effects from corticosteroids and other immunosuppressants.
• Recurrence of GN in transplant: Some GNs (e.g., FSGS, IgAN, MN) can recur in the transplanted kidney.

Prognosis

Factors

The prognosis of GN is highly variable and depends on numerous factors: * Type of Glomerulonephritis: Some types (e.g., MCD) have an excellent prognosis with treatment, while others (e.g., RPGN, severe lupus nephritis, rapidly progressive FSGS) can rapidly progress to ESRD. * Severity at Presentation: * Degree of Proteinuria: Higher proteinuria (especially in the nephrotic range) is generally associated with worse outcomes and faster progression to ESRD. * Baseline GFR: Lower GFR at diagnosis indicates more advanced kidney damage and poorer prognosis. * Presence of Crescents: Extensive crescent formation on biopsy indicates severe glomerular inflammation and rapidly progressive disease, predicting worse prognosis. * Histological Findings on Biopsy: * Activity vs. Chronicity: Biopsies showing active inflammation (e.g., cellular crescents) may respond better to immunosuppression than those showing extensive chronic damage (e.g., global glomerulosclerosis, interstitial fibrosis, tubular atrophy). * Severity of Tubulointerstitial Fibrosis: A strong predictor of progression to ESRD. * Response to Treatment: Early and sustained remission of proteinuria and stabilization of GFR are associated with better long-term outcomes. * Control of Modifiable Risk Factors: Aggressive management of hypertension, proteinuria, and dyslipidemia significantly impacts prognosis. * Blood Pressure Control: Target <130/80 mmHg, often lower for significant proteinuria. * Proteinuria Reduction: A key therapeutic target; reduction to <0.5-1 g/day is associated with improved renal survival. * Presence of Systemic Manifestations: Multi-organ involvement in systemic diseases (e.g., SLE, vasculitis) can worsen overall prognosis. * Age: Younger age at presentation for some forms (e.g., IgAN) may have a better long-term prognosis, while older age in RPGN or MN may have worse outcomes due to comorbidities.

Survival

• Minimal Change Disease: Excellent prognosis; >90% achieve remission, and most have normal long-term kidney function, though relapses are common.
• IgA Nephropathy: Highly variable; 15-40% progress to ESRD within 10-20 years. Predictors of poor outcome include heavy proteinuria, elevated creatinine at presentation, hypertension, and significant chronicity on biopsy.
• Membranous Nephropathy: Spontaneous remission in 20-30%. About 30-40% progress to ESRD over 10 years without treatment, but with modern immunosuppression, outcomes have improved.
• Focal Segmental Glomerulosclerosis (Primary): ~50% progress to ESRD within 5-10 years, particularly if steroid-resistant, or with high proteinuria and advanced fibrosis on biopsy.
• Lupus Nephritis: Improved survival with modern immunosuppression. 10-20% may progress to ESRD within 10 years, but outcomes are improving.
• ANCA-associated Vasculitis / Anti-GBM Disease: Without treatment, survival is poor. With aggressive immunosuppression and plasmapheresis, renal and patient survival have significantly improved, but a substantial proportion may still progress to ESRD or require dialysis. Relapses are common in ANCA vasculitis.

Quality of Life

Quality of life can be significantly impacted by: * Symptoms of CKD: Fatigue, pruritus, uremic symptoms. * Side Effects of Immunosuppression: Increased infection risk, weight gain, cosmetic changes (moon facies), psychological effects, diabetes, hypertension, osteoporosis. * Need for Dialysis: Major impact on daily life, physical function, and social activities. * Fear of Recurrence or Progression: Chronic anxiety. * Underlying Systemic Disease: SLE or vasculitis can have additional significant impacts on quality of life.

Prevention

Primary

Primary prevention of GN is challenging as many forms are idiopathic or triggered by immune responses. * Prompt and Adequate Treatment of Infections: Treat streptococcal pharyngitis promptly with antibiotics to reduce the risk of Post-infectious GN. However, the efficacy of antibiotics in preventing PIGN after the onset of symptoms is debated. * Vaccination: Ensure routine childhood immunizations. Influenza and pneumococcal vaccines are important, especially for individuals at risk of immunosuppression. * Avoidance of Nephrotoxic Drugs: Judicious use of NSAIDs and other potentially nephrotoxic agents, especially in individuals with existing kidney risk factors. * Control of Underlying Systemic Diseases: Aggressive management of autoimmune diseases (e.g., SLE, vasculitis) to prevent or mitigate the development of kidney involvement.

Secondary

Secondary prevention focuses on early detection and intervention to prevent progression in individuals already affected by GN or at high risk. * Early Diagnosis: Be vigilant for signs of GN in at-risk populations (e.g., microscopic hematuria/proteinuria in those with a family history or systemic disease). * Regular Screening: Routine urinalysis as part of annual physical exams can detect asymptomatic hematuria or proteinuria. * Blood Pressure Control: Strict blood pressure control (target <130/80 mmHg, often lower in patients with proteinuria) is paramount to slow kidney disease progression. ACE inhibitors or ARBs are preferred for their antiproteinuric effects. * Proteinuria Reduction: Aggressive reduction of proteinuria using ACEi/ARBs, SGLT2 inhibitors, and specific immunosuppressants. A reduction in proteinuria is a strong surrogate marker for improved renal prognosis. * Management of Dyslipidemia: Statins for hyperlipidemia to reduce cardiovascular risk. * Lifestyle Modifications: Smoking cessation, healthy diet, regular exercise, and weight management.

Tertiary

Tertiary prevention focuses on preventing complications and improving outcomes for individuals with established GN or CKD. * Optimizing Immunosuppression: Balancing efficacy with side effects to prevent disease progression while minimizing drug-related harm. * Management of CKD Complications: * Anemia: Iron supplementation, erythropoiesis-stimulating agents (ESAs). * Bone and Mineral Disorders: Phosphate binders, active vitamin D analogs, calcimimetics. * Metabolic Acidosis: Sodium bicarbonate. * Cardiovascular Risk Reduction: Comprehensive management of hypertension, dyslipidemia, diabetes, and lifestyle factors. * Infection Prophylaxis: Routine vaccinations, prompt treatment of infections, and prophylactic antibiotics when indicated for immunosuppressed patients. * Patient Education: Empowering patients with knowledge about their condition, medications, and potential complications. * Preparation for Renal Replacement Therapy: Early referral to a nephrologist for planning and education regarding dialysis or transplantation if ESRD is anticipated.

Special Populations

Pediatric

• Etiology: Differing prevalence of specific GNs. Minimal Change Disease is the most common cause of nephrotic syndrome in children. Post-infectious GN is also more common than in adults.
• Growth and Development: Immunosuppressive therapies (especially corticosteroids) can impair growth. Long-term monitoring of growth and bone health is critical.
• Drug Dosing: Dosing must be adjusted for weight and body surface area.
• Psychosocial Impact: Chronic illness and steroid side effects can have significant psychosocial impacts on children and their families.
• Vaccinations: Catch-up on routine vaccinations and consider additional vaccines (e.g., varicella, measles, mumps, rubella) before starting immunosuppression.
• Kidney Biopsy: Requires careful consideration, often performed under general anesthesia or heavy sedation.

Geriatric

• Comorbidities: Elderly patients often have multiple comorbidities (e.g., hypertension, diabetes, cardiovascular disease), which can complicate GN management and increase the risk of side effects from immunosuppressants.
• Reduced Renal Reserve: Baseline GFR is often lower, making them more susceptible to AKI and nephrotoxic side effects.
• Polypharmacy: Increased risk of drug-drug interactions.
• Atypical Presentation: GN may present atypically or with more subtle symptoms, leading to delayed diagnosis.
• Immunosuppression: Immunosuppressive regimens may need to be less aggressive or dose-adjusted due to increased risk of infections and other adverse events. Baseline frailty assessment is important.
• Prognosis: Often worse outcomes due to higher baseline risk of complications and limited tolerance to aggressive therapies.

Pregnancy

• Drug Safety: Many immunosuppressants (e.g., cyclophosphamide, MMF, ACEi/ARBs) are teratogenic or contraindicated during pregnancy. MMF must be discontinued at least 6 weeks prior to conception. Azathioprine and low-dose corticosteroids are generally considered safer.
• Disease Activity: Pregnancy can sometimes trigger flares of autoimmune diseases (e.g., lupus nephritis) or worsen proteinuria.
• Preeclampsia Risk: Increased risk of superimposed preeclampsia, especially in patients with pre-existing CKD, hypertension, or nephrotic syndrome. Distinguishing between a GN flare and preeclampsia can be challenging.
• Monitoring: Frequent monitoring of blood pressure, proteinuria, and kidney function.
• Fetal Monitoring: Close monitoring of fetal growth and well-being.
• Delivery: Timing and mode of delivery require careful planning, often in collaboration with obstetrics.

Comorbidities

• Diabetes Mellitus: Diabetes and GN can coexist. Diabetic nephropathy can complicate the histological interpretation. ACEi/ARBs are renoprotective for both. SGLT2 inhibitors show benefits.
• Cardiovascular Disease: High prevalence in CKD. Aggressive management of all cardiovascular risk factors (hypertension, dyslipidemia, smoking, obesity).
• Infections: Immunosuppressed GN patients are at high risk. Requires vigilant screening, prompt treatment, and sometimes prophylactic antibiotics/antivirals.
• Malignancy: Increased risk with long-term immunosuppression. Regular cancer screening is important.
• Obesity: Can contribute to FSGS (obesity-related glomerulopathy), and makes kidney biopsy more challenging. Increases cardiovascular risk.
• Liver Disease: Chronic liver disease (e.g., Hepatitis C) can be associated with cryoglobulinemic GN or MPGN. Management needs to consider liver function and potential drug interactions.

Clinical Pearls

Diagnostic

• Always suspect GN with Hematuria, Proteinuria, and Hypertension: This triad is a strong indicator.
• RBC Casts are Pathognomonic: While rare, their presence on urinalysis confirms glomerular bleeding. Dysmorphic RBCs are also highly suggestive.
• Biopsy is King: A kidney biopsy is often essential for definitive diagnosis, classification, prognostication, and guiding specific treatment, especially in nephritic syndrome or rapidly progressive disease. Do not delay if RPGN is suspected.
• Look Beyond the Kidney: GN is often a manifestation of a systemic disease. A thorough systemic review of symptoms and targeted serological workup (ANA, ANCA, anti-GBM, etc.) are crucial.
• Low Complement Levels are Key: Consider PIGN, Lupus Nephritis, MPGN, or cryoglobulinemia when C3 and/or C4 are low.
• Frothy Urine = Proteinuria: Ask patients about it, as it's a common, often overlooked symptom.

Treatment

• Tailor Therapy to Biopsy: Do not initiate broad immunosuppression without a definitive histological diagnosis, unless RPGN is highly suspected and delaying treatment would risk irreversible kidney damage.
• Aggressive BP and Proteinuria Control: These are fundamental irrespective of GN type. ACEi/ARBs are first-line. SGLT2 inhibitors are emerging as highly beneficial for proteinuria reduction.
• Balance Benefits vs. Risks of Immunosuppression: High-dose steroids and cytotoxic agents carry significant side effects. Careful patient selection, monitoring, and proactive management of side effects (e.g., PJP prophylaxis, gastric protection, bone density scans) are critical.
• Long-Term Follow-up: Many GNs are chronic. Consistent long-term follow-up is necessary to monitor disease activity, medication side effects, and progression of CKD.
• Patient Education: Educate patients thoroughly about their disease, medications, the importance of adherence, and potential complications. Empower them to self-monitor BP and report new symptoms.
• Consider Referral: Early referral to a nephrologist for any suspected GN is crucial.

Pitfalls

• Delay in Diagnosis of RPGN: Missing RPGN can lead to irreversible kidney failure. High index of suspicion is vital in patients with rapidly declining kidney function.
• Inadequate Blood Pressure Control: Poorly controlled hypertension accelerates kidney damage and increases cardiovascular risk.
• Under-treatment or Over-treatment with Immunosuppression:
  • Under-treatment leads to disease progression.
  • Over-treatment increases infection risk and other serious side effects.
• Failure to Manage Proteinuria: Persistent heavy proteinuria is a major driver of CKD progression.
• Ignoring Comorbidities: Neglecting conditions like diabetes, dyslipidemia, or cardiovascular disease will worsen overall prognosis.
• Discontinuation of ACEi/ARB Prematurely: Do not stop ACEi/ARBs for a small rise in creatinine (up to 20-30%) as long as hyperkalemia is not severe and AKI is not worsening. This is often an expected hemodynamic effect and indicates efficacy in reducing glomerular pressure.
• Lack of Infection Prophylaxis: In immunosuppressed patients, failure to provide appropriate prophylaxis (e.g., for Pneumocystis jirovecii pneumonia) can have devastating consequences.

Recent Updates

Guidelines

• KDIGO (Kidney Disease: Improving Global Outcomes): Continually updates clinical practice guidelines for various GNs.
  • KDIGO 2021 Glomerular Diseases Guideline: Comprehensive update covering IgA nephropathy, membranous nephropathy, MCD, FSGS, MPGN, and lupus nephritis. Emphasizes risk stratification, shared decision-making, and individualized treatment.
  • KDIGO 2021 Clinical Practice Guideline for the Management of Blood Pressure in CKD: Recommends a target systolic BP of <120 mmHg for most adults with CKD (not on dialysis), if tolerated.
  • KDIGO 2022 Clinical Practice Guideline for Diabetes Management in CKD: Reinforces the role of SGLT2 inhibitors and GLP-1 receptor agonists for renoprotection in diabetic and non-diabetic CKD.

Evidence

• SGLT2 Inhibitors: Landmark trials (DAPA-CKD, EMPA-KIDNEY) have demonstrated significant benefits of SGLT2 inhibitors (dapagliflozin, empagliflozin) in slowing CKD progression and reducing cardiovascular events in patients with CKD, including those without diabetes and with various underlying GNs (e.g., IgAN). They are increasingly being incorporated into standard care for proteinuria management.
• Targeted Therapies for IgA Nephropathy:
  • Budesonide (Nefecon): A gut-targeted, delayed-release corticosteroid, has shown promise in reducing proteinuria and stabilizing eGFR in IgAN in the NefIgArd trial, now approved in several regions.
  • Complement Pathway Inhibition: Therapies targeting the complement system (e.g., spesolimab, a C5a receptor inhibitor) are under investigation with promising early results.
  • Endothelin Receptor Antagonists: Atrasentan (an investigational selective endothelin A receptor antagonist) has shown efficacy in reducing proteinuria in IgAN.
• Membranous Nephropathy: Rituximab is increasingly recognized as a first-line alternative to cyclophosphamide-based regimens for moderate-to-high risk primary MN, supported by trials like the STARMEN study. Anti-PLA2R antibody levels are critical for guiding therapy and monitoring response.
• Lupus Nephritis: Voclosporin, a calcineurin inhibitor, has been approved for active lupus nephritis in combination with MMF and corticosteroids, based on the AURORA trials, showing improved renal response rates. Belimumab (anti-BLyS antibody) has also been approved as an add-on therapy for active lupus nephritis.
• ANCA-associated Vasculitis: Advancements in maintenance therapy with Rituximab demonstrating non-inferiority to Azathioprine, offering an alternative for patients. Lower-dose cyclophosphamide regimens have also been optimized to reduce toxicity.

Controversies

• Optimal Duration of Immunosuppression: For many GNs (e.g., lupus nephritis, ANCA vasculitis), the optimal duration of maintenance immunosuppression remains debated, balancing relapse prevention against cumulative toxicity.
• Role of Repeat Biopsy: When and if to perform repeat kidney biopsy for monitoring disease activity or guiding treatment intensification (e.g., in refractory cases or after treatment).
• Dietary Interventions: While sodium restriction is standard, the role of specific dietary interventions (e.g., gluten-free, low-antigenic) for certain GNs (e.g., IgAN) is not well-established.
• Management of Steroid-Resistant FSGS: Treatment strategies beyond CNIs are still evolving, with a need for more effective and less toxic options.
• Anticoagulation in Nephrotic Syndrome: Precise indications and duration for prophylactic anticoagulation, especially with moderate hypoalbuminemia, remain an area of ongoing debate.

Key References

Guidelines

• KDIGO 2021 Clinical Practice Guideline for the Management of Glomerular Diseases: The most comprehensive and current guidelines covering most common forms of GN.
  • Kidney Int. 2021 Dec;100(6S):S1-S276. DOI: 10.1016/j.kint.2021.05.021.
• KDIGO 2021 Clinical Practice Guideline for the Management of Blood Pressure in CKD:
  • Kidney Int. 2021 Mar;99(3S):S1-S87. DOI: 10.1016/j.kint.2020.11.003.
• KDIGO 2022 Clinical Practice Guideline for Diabetes Management in CKD:
  • Kidney Int. 2022 Nov;102(5S):S1-S127. DOI: 10.1016/j.kint.2022.08.019.
• EULAR/ERA-EDTA recommendations for the management of adult and paediatric lupus nephritis:
  • Ann Rheum Dis. 2012 Nov;71(11):1765-72. DOI: 10.1136/annrheumdis-2012-201940. (Awaiting updated EULAR/ERA guidelines).

Studies

• NefIgArd Trial (IgA Nephropathy):
  • Barratt J, et al. A Randomized, Double-Blind, Placebo-Controlled Trial of Nefecon in Patients with Primary IgA Nephropathy (NefIgArd). Kidney Int Rep. 2023 Mar;8(3):517-526. DOI: 10.1016/j.ekir.2022.12.016.
• STARMEN Trial (Membranous Nephropathy):
  • Fervenza FC, et al. Rituximab or Cyclosporine in the Treatment of Membranous Nephropathy. N Engl J Med. 2019 Jul 4;381(1):15-26. DOI: 10.1056/NEJMoa1814427.
• AURORA Trial (Lupus Nephritis):
  • Rovin BH, et al. Efficacy and safety of voclosporin versus placebo for lupus nephritis (AURORA 1): a phase 3, randomised, double-blind, multicentre, placebo-controlled trial. Lancet. 2021 Mar 13;397(10289):2070-2081. DOI: 10.1016/S0140-6736(21)00578-X.
• DAPA-CKD Trial (SGLT2i in CKD):
  • Heerspink HJL, et al. Dapagliflozin in Patients with Chronic Kidney Disease. N Engl J Med. 2020 Oct 8;383(15):1436-1446. DOI: 10.1056/NEJMoa2024816.
• EMPA-KIDNEY Trial (SGLT2i in CKD):
  • The EMPA-KIDNEY Collaborative Group. Empagliflozin in Patients with Chronic Kidney Disease. N Engl J Med. 2023 Mar 2;388(13):1173-1184. DOI: 10.1056/NEJMoa2204233.

Reviews

• Jha V, et al. Chronic kidney disease: global dimensions and perspectives. Lancet. 2013 Jul 20;382(9888):260-72. DOI: 10.1016/S0140-6736(13)60680-7.
• Glassock RJ, et al. The pathogenesis of IgA nephropathy. Kidney Int. 2017 Jan;91(1):15-27. DOI: 10.1016/j.kint.2016.08.016.
• Couser WG. Pathogenesis of glomerular injury in crescentic glomerulonephritis. Kidney Int. 2005 Sep;68(3):927-37. DOI: 10.1111/j.1523-1755.2005.00486.x.