Srns

Disclaimer: This document provides comprehensive medical information for educational purposes and should not be considered a substitute for professional medical advice, diagnosis, or treatment. Clinical decisions must always be made by a qualified healthcare professional, considering the individual patient's circumstances and current medical evidence.

Overview

• Definition: Steroid-Resistant Nephrotic Syndrome (SRNS) is defined by the failure to achieve complete remission (proteinuria < 4 mg/m²/hour or urine protein-creatinine ratio < 0.2 mg/mg, and serum albumin > 3.5 g/dL) despite adequate treatment with high-dose corticosteroids for a sufficient duration. The standard definition typically involves a lack of remission after 4 weeks of daily prednisolone (or equivalent) at 60 mg/m²/day (maximum 60-80 mg/day) or 2 mg/kg/day (maximum 80 mg/day), followed by 4 weeks of alternate-day prednisolone at 40 mg/m²/day (maximum 40-60 mg/day) or 1.5 mg/kg/day (maximum 60 mg/day). In some definitions, 8 weeks of daily steroid therapy is considered.
• Epidemiology:
  • Nephrotic syndrome (NS) affects approximately 1-3 per 100,000 children annually and 3 per 100,000 adults annually.
  • SRNS accounts for about 10-20% of all childhood NS cases and a higher proportion (up to 50%) of adult NS cases.
  • Incidence of primary FSGS (a common cause of SRNS) has been rising globally.
  • Genetic forms of SRNS are more prevalent in familial cases and early-onset disease (e.g., congenital NS, onset < 3 months).
• Classification:
  • Primary (Idiopathic) SRNS: No identifiable systemic cause. Most commonly associated with Focal Segmental Glomerulosclerosis (FSGS), but can also be Minimal Change Disease (MCD) (though rare to be truly resistant if MCD) or Membranoproliferative Glomerulonephritis (MPGN).
  • Secondary SRNS: Due to an underlying systemic disease (e.g., Lupus Nephritis, Diabetic Nephropathy, Amyloidosis, HIV-associated nephropathy, drug-induced, pre-eclampsia, sickle cell disease) or a genetic mutation.
  • Genetic SRNS: Caused by pathogenic variants in genes encoding podocyte proteins (e.g., NPHS1 [nephrin], NPHS2 [podocin], WT1, TRPC6, ACTN4, PLCE1, INF2, CD2AP, COL4A5). These typically present early in life and often have a poorer prognosis, with limited response to immunosuppression.

Pathophysiology

• Mechanism: SRNS is fundamentally a podocytopathy, characterized by injury to the glomerular podocytes, leading to effacement of foot processes and a breakdown of the glomerular filtration barrier.
  • Immune-mediated (Primary): In cases of idiopathic FSGS or MCD (rarely), circulating factors (e.g., "permeability factor") are hypothesized to cause podocyte damage, though specific factors remain elusive. T-cell dysregulation or B-cell mediated immunity may play a role.
  • Genetic: Mutations in genes encoding key structural or functional podocyte proteins (e.g., nephrin, podocin, alpha-actinin-4, TRPC6 channel) lead to inherent podocyte dysfunction, apoptosis, or detachment, compromising the filtration barrier. These forms are often non-responsive to immunosuppression.
  • Hemodynamic/Adaptive: In some cases, hyperfiltration or loss of renal mass can lead to secondary FSGS, which can be steroid-resistant.
  • Other causes (Secondary): Direct toxic effects (drugs), inflammation (lupus), metabolic derangements (diabetes), or deposition of abnormal proteins (amyloid).
• Risk Factors:
  • Histological subtype: FSGS is the most common cause of SRNS, particularly collapsing variant or diffuse mesangial sclerosis (in congenital/infantile forms).
  • Younger age at onset (especially < 1 year): Higher likelihood of genetic causes.
  • Early progression to end-stage renal disease (ESRD): Indicates severe podocyte damage.
  • Absence of complete remission with initial steroid therapy.
  • High initial proteinuria (> 10 g/day or urine protein-creatinine ratio > 10).
  • Presence of genetic mutations.
  • African ancestry (higher prevalence of APOL1 risk alleles).
• Protective Factors: N/A for SRNS directly. Factors that indicate better prognosis or response to treatment in steroid-sensitive NS do not apply here. For SRNS, early diagnosis and aggressive management to prevent complications and delay progression to ESRD are key.

Clinical Presentation

Signs and Symptoms

• Cardinal Features: Persistent, significant edema despite initial steroid therapy (anasarca, periorbital edema, ascites, scrotal/labial edema).
  • Proteinuria: Nephrotic range (urine protein excretion > 3.5 g/1.73 m²/day in adults; > 40 mg/m²/hr or urine protein-creatinine ratio > 2 mg/mg in children).
  • Hypoalbuminemia: Serum albumin < 3.0-3.5 g/dL.
  • Hyperlipidemia: Total cholesterol > 200 mg/dL, triglycerides > 150 mg/dL.
• Early Signs: Edema (often initially facial/periorbital), foamy urine (due to proteinuria), weight gain.
• Advanced Signs:
  • Severe anasarca.
  • Symptoms of complications: Abdominal pain (peritonitis), fever (infection), dyspnea (pleural effusions, pulmonary edema, DVT/PE), oliguria/anuria (AKI).
  • Symptoms of uremia if progressing to ESRD: Fatigue, nausea, pruritus, neurological changes.
• Atypical Presentations:
  • Gross hematuria (rare, consider IgA nephropathy, MPGN).
  • Hypertension (common but can be severe).
  • Microscopic hematuria (present in about 20-30% of FSGS cases).
  • Family history of kidney disease or NS (suggests genetic cause).

Physical Examination

• Inspection:
  • Pitting edema (generalized, particularly dependent areas: ankles, sacrum, eyelids, periorbital).
  • Ascites (distended abdomen, shifting dullness).
  • Pleural effusions (diminished breath sounds, dullness to percussion).
  • Weight gain.
  • Signs of infection (e.g., cellulitis, peritonitis with guarding/rebound tenderness).
  • Xanthelasma, xanthomas (due to hyperlipidemia).
  • Pallor (anemia from chronic disease or iron deficiency).
• Palpation:
  • Pitting edema.
  • Abdominal tenderness (peritonitis).
  • Hepatomegaly (fluid overload, fatty liver).
• Special Tests:
  • Blood pressure measurement (often normal or mildly elevated, but can be significantly high in some cases).
  • Fluid balance assessment (daily weights, input/output).

Diagnostic Approach

History Taking

• Key Questions:
  • Onset and duration of edema and other symptoms: When did they start? How quickly did they progress?
  • Response to initial steroid therapy: Exact dose, duration, and degree of proteinuria reduction (if any). This is crucial for defining SRNS.
  • Past medical history: Any systemic diseases (lupus, diabetes), previous kidney disease, infections (e.g., HIV, hepatitis B/C).
  • Medication history: Especially NSAIDs, heroin, pamidronate, lithium, interferon.
  • Family history: Any family members with kidney disease, early-onset kidney failure, or nephrotic syndrome.
  • Travel history: Endemic areas for parasitic infections.
  • Recent infections: Upper respiratory tract infections, gastroenteritis (can precipitate relapse in SSNS, but less directly cause SRNS).
• Red Flags:
  • Rapid decline in renal function.
  • Severe hypertension.
  • Signs of acute infection (fever, localized pain).
  • Symptoms of thrombosis (unilateral limb swelling, chest pain, dyspnea).
  • Symptoms suggestive of systemic vasculitis or lupus.

Laboratory Tests

• First-Line:
  • Urinalysis with microscopy: Heavy proteinuria (3+ to 4+ by dipstick), bland urine sediment (no casts, few cells typical for MCD/FSGS), or occasional microscopic hematuria.
  • Urine protein-creatinine ratio (UPCR) or 24-hour urine protein: To quantify proteinuria. UPCR > 2 mg/mg (adults), > 2 mg/mg or > 200 mg/mmol (children).
  • Serum chemistry:
    • Serum albumin: Often < 2.5 g/dL.
    • Serum creatinine and BUN: To assess kidney function.
    • Electrolytes: Sodium, potassium (can be affected by diuretics).
  • Lipid panel: Total cholesterol, LDL, HDL, triglycerides (typically elevated).
  • Complete Blood Count (CBC): May show elevated hemoglobin (hemoconcentration) or anemia (chronic disease, iron deficiency).
• Confirmatory:
  • Renal Biopsy: Essential for definitive diagnosis of the underlying histopathology (e.g., FSGS, MCD, MPGN, lupus nephritis). This guides further management, especially in SRNS.
  • Genetic Testing: Strongly recommended for children with SRNS (especially if onset < 1 year, familial cases, or diffuse mesangial sclerosis/collapsing FSGS on biopsy). Panel testing for common podocyte genes (e.g., NPHS1, NPHS2, WT1, TRPC6, INF2, ACTN4, PLCE1, CD2AP, COL4A5).
• Monitoring:
  • Repeat UPCR/24-hour urine protein: To monitor response to therapy.
  • Serum albumin: To monitor nutritional status and response.
  • Serum creatinine/eGFR: To monitor kidney function and progression.
  • Lipid panel: To monitor hyperlipidemia.
  • Drug levels: For immunosuppressants like cyclosporine or tacrolimus (trough levels).

Imaging

• Recommended:
  • Renal Ultrasound with Doppler: To assess kidney size, echogenicity, rule out urinary tract obstruction, and evaluate renal vasculature (e.g., renal vein thrombosis). Kidney size may be normal or increased in early disease, but may be small and echogenic in chronic disease.
• Advanced:
  • CT Angiography/Venography or MRI/MRA: If renal vein thrombosis or other vascular complications are suspected.
  • Echocardiogram: If signs of severe fluid overload or cardiac involvement are present.

Management

Acute Management

• Immediate:
  • Fluid and Electrolyte Management: Address severe edema with cautious diuresis.
  • Assessment for complications: Rule out peritonitis, thrombosis, severe infections.
• Stabilization:
  • Diuretics: Loop diuretics (e.g., Furosemide) are first-line. Dosing individualized based on edema severity and renal function.
    • Adults: Furosemide 20-80 mg PO BID-TID, or continuous IV infusion 5-20 mg/hr for severe edema.
    • Children: Furosemide 1-2 mg/kg/dose PO or IV every 6-12 hours.
    • Consider adding thiazide diuretics (e.g., Metolazone 2.5-10 mg PO QD or QOD) for synergy in refractory edema.
  • Albumin Infusion: For symptomatic hypovolemia or severe anasarca with impaired organ function (e.g., respiratory distress from ascites/pleural effusions). Typically 25% albumin, 0.5-1 g/kg (max 100g) given over 2-4 hours, often followed by furosemide to mobilize fluid into the intravascular space.
  • Anticoagulation: Prophylactic anticoagulation for high-risk patients (e.g., severe hypoalbuminemia < 2.0-2.5 g/dL, morbid obesity, prolonged immobilization, history of thrombosis, or specific prothrombotic mutations). Therapeutic anticoagulation for confirmed thrombosis. Low molecular weight heparin (LMWH) is preferred.
  • Antibiotics: Prompt treatment of infections. Prophylactic antibiotics (e.g., Penicillin V) are considered in some centers during severe hypoalbuminemia (albumin < 2.0 g/dL) or during varicella exposure in non-immune patients.
• Emergency:
  • Respiratory Compromise: Due to massive ascites or pleural effusions - may require paracentesis or thoracentesis.
  • Acute Kidney Injury: Investigate causes (hypovolemia, ATN, renal vein thrombosis) and manage appropriately.
  • Sepsis: Prompt initiation of empiric broad-spectrum antibiotics and supportive care.

Chronic Management

Management of SRNS is complex and often requires multi-drug regimens and close monitoring. It is guided by renal biopsy findings, patient age, and previous treatment responses. Genetic SRNS typically responds poorly to immunosuppression. - Pharmacological: * Calcineurin Inhibitors (CNIs): First-line immunosuppressants for most idiopathic SRNS cases (especially FSGS). * Cyclosporine (CSA): 3-5 mg/kg/day divided BID (initial dose). Target trough levels: 100-150 ng/mL for initial treatment, 75-125 ng/mL for maintenance. Monitor renal function and blood pressure closely. * Tacrolimus (TAC): 0.05-0.1 mg/kg/day divided BID (initial dose). Target trough levels: 5-10 ng/mL for initial treatment, 3-7 ng/mL for maintenance. Also monitor renal function and blood pressure. * Duration: Typically continued for at least 12-24 months after remission, then tapered slowly. * Mycophenolate Mofetil (MMF): Often used as an add-on or alternative, particularly if CNIs are not tolerated or partially effective. * Adults: 1000-1500 mg PO BID. * Children: 600 mg/m²/dose PO BID (max 1g BID). * Rituximab (anti-CD20 monoclonal antibody): Increasingly used for both steroid-dependent and SRNS, especially in pediatric populations. Often considered for CNI-dependent or CNI-intolerant patients, or those with frequent relapses. * Dose: 375 mg/m² IV once weekly for 4 doses OR single dose 375 mg/m² IV (recent studies suggest single dose may be effective). Repeated based on CD19/CD20 B-cell counts and clinical response. * Cyclophosphamide (CYC): Less commonly used now due to toxicity (gonadal, bladder) and availability of safer alternatives, but may be considered for severe refractory cases or specific histologies. * Dose: 2-2.5 mg/kg/day PO for 8-12 weeks (total cumulative dose < 160-200 mg/kg). * Corticosteroids: Usually maintained at a low dose (e.g., Prednisone 0.1-0.2 mg/kg/day or alternate day) or slowly tapered off, depending on the response to second-line agents. * Other agents: * ACE Inhibitors/Angiotensin Receptor Blockers (ACEi/ARBs): Essential for reducing proteinuria and managing hypertension, even in the absence of hypertension. Titrate slowly to achieve desired effect (urine protein-creatinine ratio < 0.5-1.0) while monitoring renal function and potassium. * Statins: For hyperlipidemia, especially if persistent despite remission or high cardiovascular risk. * Vitamin D analogues: To address vitamin D deficiency common in NS. - Non-pharmacological: * Dietary sodium restriction: < 2 g/day for adults, proportionate reduction for children, to control edema. * Fluid restriction: Only if severe hyponatremia (< 125 mmol/L) or severe fluid overload. * Low-fat, low-cholesterol diet: To manage hyperlipidemia. * Blood pressure control: Target < 130/80 mmHg or < 90th percentile for age/sex/height in children. * Vaccinations: Ensure up-to-date immunizations. Live vaccines are contraindicated while on immunosuppression. - Monitoring: * Clinical: Daily weights, blood pressure, edema assessment. * Laboratory: Weekly/bi-weekly initially, then monthly/quarterly: UPCR, serum albumin, creatinine/eGFR, electrolytes, lipids, CBC, CNI trough levels (if applicable). Genetic testing results. * Side Effects: Monitor for CNI nephrotoxicity, hypertension, infections, myelosuppression (MMF, CYC), diabetes.

Treatment Algorithms

• First-Line (for idiopathic SRNS):
  1. Renal Biopsy: Confirm diagnosis and rule out secondary causes.
  2. Calcineurin Inhibitors (CNIs): Cyclosporine or Tacrolimus are generally first-line for idiopathic FSGS/MCD resistant to steroids. Administer for at least 3-6 months.
     • Response to CNI: If complete or partial remission, continue CNI for 12-24 months after remission, then attempt slow taper. Add ACEi/ARB for proteinuria.
• Second-Line (for idiopathic SRNS):
  1. If no/partial response to CNI after 3-6 months:
     • Consider Rituximab: Especially in CNI-intolerant or CNI-dependent patients, or in frequent relapsers/SRNS with sustained proteinuria.
     • Consider Mycophenolate Mofetil (MMF): Often used in combination with low-dose steroids or with CNI, or as alternative.
     • Consider Pulse Methylprednisolone: For severe flares or initial non-responders, before switching therapies.
• Refractory Cases:
  • Combined therapy: CNI + MMF + low-dose steroids.
  • Cyclophosphamide: If other agents fail and biopsy suggests a primary immune-mediated process.
  • Novel therapies: Adrenocorticotropic hormone (ACTH) analogues (e.g., Acthar Gel), Ofatumumab (anti-CD20, for rituximab non-responders), Apremilast, Sirolimus/Everolimus (mTOR inhibitors - can be complex, some data for efficacy in specific forms of FSGS or as steroid-sparing).
  • Plasmapheresis/Immunoadsorption: May be considered for rapidly progressive FSGS, especially in post-transplant recurrence.
  • Genetic SRNS: Immunosuppressive therapies are generally ineffective. Management focuses on supportive care, proteinuria reduction (ACEi/ARB), and preparing for ESRD.
  • Recurrence Post-Transplant: For FSGS, recurrence can be aggressive. Treatment includes plasmapheresis, rituximab, and increased immunosuppression.

Complications

• Common:
  • Infections: Due to hypoalbuminemia (impaired opsonization), immunosuppression, IgG loss in urine. Common sites: spontaneous bacterial peritonitis, cellulitis, pneumonia, urinary tract infections.
  • Thrombosis: Hypercoagulable state due to urinary loss of antithrombin III, increased procoagulant factors (fibrinogen, Factor VIII), increased platelet aggregation. Common sites: renal vein thrombosis, deep vein thrombosis (DVT), pulmonary embolism (PE).
  • Acute Kidney Injury (AKI): Due to hypovolemia, interstitial nephritis (from drugs), renal vein thrombosis, or disease progression.
  • Hypertension: Can be a cause or consequence of kidney disease progression.
  • Hyperlipidemia: Contributes to cardiovascular risk.
• Serious:
  • End-Stage Renal Disease (ESRD): The most serious long-term complication; SRNS is a leading cause of ESRD in children and young adults.
  • Sepsis: Life-threatening infection.
  • Fatal Thrombotic Events: PE, stroke.
  • Cardiovascular disease: Accelerated atherosclerosis.
• Long-term:
  • Chronic Kidney Disease (CKD) progression to ESRD.
  • Growth retardation (in children) due to chronic disease and steroid use.
  • Bone disease (osteoporosis/osteopenia) from chronic steroid use and vitamin D deficiency.
  • Cataracts, glaucoma (from steroid use).
  • Neurotoxicity/nephrotoxicity from immunosuppressants (CNIs).

Prognosis

• Factors:
  • Histological type: FSGS has a worse prognosis than MCD. Collapsing FSGS carries the poorest prognosis.
  • Response to treatment: Complete remission is the strongest predictor of good renal outcome. Partial remission is better than no remission.
  • Genetic mutations: Patients with genetic causes of SRNS often have a poorer prognosis, with limited or no response to immunosuppression, and higher likelihood of ESRD.
  • Degree of proteinuria: Higher persistent proteinuria portends a worse outcome.
  • Baseline renal function: Higher creatinine at diagnosis implies more advanced disease and worse prognosis.
  • Age at onset: Very young children (< 1 year) are at higher risk for genetic SRNS and progression to ESRD.
• Survival:
  • Overall mortality is low but significantly higher than general population, largely due to complications (infection, cardiovascular events) and progression to ESRD.
  • For idiopathic SRNS, about 50-70% may achieve remission with second-line agents. However, a significant proportion (30-50%) will progress to ESRD within 5-10 years.
  • Genetic SRNS has a very high risk of progression to ESRD (often > 80-90% by adulthood).
• Quality of Life:
  • Significantly impacted by chronic disease, recurrent relapses, medication side effects, frequent hospitalizations, and progression to ESRD requiring dialysis or transplantation.
  • Emotional and psychological burden on patients and families.

Prevention

• Primary: Currently, there are no established primary prevention strategies for idiopathic or genetic SRNS.
• Secondary:
  • Early diagnosis and prompt management: Aggressive management of proteinuria and underlying kidney disease aims to prevent or delay progression to ESRD.
  • Close monitoring of renal function: To detect decline early.
  • Genetic counseling: For families with genetic forms of SRNS to understand recurrence risk.
• Tertiary:
  • Aggressive management of complications: Timely treatment of infections, prompt anticoagulation for thrombosis, strict blood pressure control, and lipid management.
  • Nutritional support: To prevent malnutrition and growth failure.
  • Dialysis and kidney transplantation: For patients who progress to ESRD. Recurrence of FSGS post-transplant is a major challenge (20-50% risk, higher in rapidly progressive native disease).

Special Populations

• Pediatric:
  • SRNS accounts for a higher proportion of ESRD in children compared to adults.
  • Genetic causes are more prevalent, especially in congenital (< 3 months) and infantile (< 1 year) onset. Genetic testing is highly recommended.
  • Growth and development are critical considerations; chronic steroid use can impair growth.
  • Dosing of medications (immunosuppressants, diuretics) must be weight/BSA-based.
  • Psychosocial support for child and family is crucial.
• Geriatric:
  • Primary SRNS (e.g., idiopathic FSGS) is less common, but secondary causes (e.g., amyloidosis, drug-induced, malignancy-associated) are more frequent.
  • Increased risk of medication side effects and complications (infections, thrombosis) due to comorbidities and polypharmacy.
  • Renal function may already be compromised; careful dosing of nephrotoxic drugs.
• Pregnancy:
  • SRNS during pregnancy poses risks to both mother and fetus. Proteinuria can worsen.
  • Increased risk of pre-eclampsia, thrombosis, and preterm delivery.
  • Immunosuppressants (e.g., cyclophosphamide, mycophenolate mofetil, ACEi/ARBs) are generally contraindicated or require careful risk-benefit assessment due to teratogenicity. Cyclosporine and tacrolimus are relatively safer but require close monitoring.
  • Close multidisciplinary management is essential.
• Comorbidities:
  • Hypertension: Aggressive management with ACEi/ARBs is key to reduce proteinuria and slow progression.
  • Diabetes Mellitus: Diabetic nephropathy can cause secondary SRNS. Management includes tight glycemic control. Immunosuppressants need careful consideration due to infection risk.
  • HIV Infection: HIV-associated nephropathy (HIVAN) often presents as SRNS with collapsing FSGS. Antiretroviral therapy (ART) is the cornerstone; immunosuppression is generally not indicated for HIVAN itself.
  • Systemic Lupus Erythematosus (SLE): Lupus nephritis can cause SRNS. Management is directed at the underlying lupus activity.

Clinical Pearls

• Diagnostic:
  • Biopsy is paramount: Never delay kidney biopsy in SRNS to confirm histology and guide therapy, unless a clear genetic cause is identified.
  • Genetic testing early: Consider genetic testing for all children with SRNS, especially with early onset, familial history, or specific biopsy findings (e.g., diffuse mesangial sclerosis). It can avoid unnecessary immunosuppression if a non-responsive genetic mutation is found.
  • Exclude secondary causes: Always rule out systemic diseases, infections, and drug-induced causes before diagnosing idiopathic SRNS.
• Treatment:
  • CNIs are generally first-line for idiopathic SRNS: Start at appropriate doses and monitor trough levels closely to ensure therapeutic efficacy and minimize toxicity.
  • ACEi/ARBs are essential supportive therapy: Regardless of blood pressure, they help reduce proteinuria and protect kidney function.
  • Manage complications aggressively: Proactive management of infections, thrombosis, and fluid overload can prevent life-threatening events.
  • Avoid prolonged steroid use: Once SRNS is confirmed, transition to steroid-sparing agents to minimize long-term side effects.
• Pitfalls:
  • Inadequate steroid trial: Do not prematurely label a patient as SRNS without a sufficient duration and dose of corticosteroids.
  • Delaying biopsy: Postponing biopsy can lead to delayed diagnosis of specific histologies (e.g., collapsing FSGS) that might require more urgent intervention or influence prognosis.
  • Over-diuresis: Can lead to intravascular volume depletion and AKI, worsening renal function.
  • Ignoring hyperlipidemia: Increases cardiovascular risk long-term.
  • Failure to monitor drug levels: Leads to sub-therapeutic dosing or toxicity of immunosuppressants.
  • Forgetting about rare secondary causes: Always consider all possibilities.

Recent Updates

• Guidelines: KDIGO 2021 Clinical Practice Guideline for the Management of Glomerular Diseases provides updated recommendations for the diagnosis and management of SRNS, emphasizing biopsy-guided therapy and the role of genetic testing.
• Evidence:
  • Growing evidence supports the use of Rituximab as an effective second-line agent, particularly for CNI-dependent or CNI-intolerant patients, and for frequent relapses. Single-dose rituximab protocols are being studied for efficacy and safety.
  • Increased understanding of the broad spectrum of genetic causes of SRNS, with identification of new genes and more widespread use of next-generation sequencing for diagnosis. This is shifting the paradigm from purely immune-mediated to a more personalized approach.
  • Emerging data on the use of mTOR inhibitors (Sirolimus, Everolimus) in specific forms of FSGS (e.g., those related to TRPC6 or INF2 mutations, or post-transplant recurrent FSGS) and as steroid-sparing agents.
  • Research into circulating "permeability factors" in idiopathic FSGS continues, with potential for future targeted therapies.
• Controversies:
  • Optimal duration and tapering strategy for CNI therapy.
  • Role and timing of rituximab in the treatment algorithm (early vs. late).
  • The precise utility of newer agents (e.g., ACTH analogues, sparsentan, SGLT2 inhibitors) in specific SRNS populations outside of general proteinuria reduction.
  • Management of recurrent FSGS post-transplant: efficacy of different treatment regimens (plasmapheresis, rituximab, increased immunosuppression).

Key References

• Guidelines:
  • Kidney Disease: Improving Global Outcomes (KDIGO) Glomerular Diseases Guideline (2021). Kidney Int. 2021;100(4S):S1-S276.
  • European Society for Paediatric Nephrology (ESPN) / European Renal Association–European Dialysis and Transplant Association (ERA-EDTA) Registry recommendations for the diagnosis and management of steroid-sensitive nephrotic syndrome. Pediatr Nephrol. 2012;27(1):15-28. (While focused on SSNS, it provides context for resistance definition).
• Studies:
  • Trautmann A, et al. Rituximab for steroid-dependent nephrotic syndrome in children: a multicenter retrospective study. J Am Soc Nephrol. 2011;22(9):1751-1756.
  • Ruf RG, et al. WT1 mutations in early steroid-resistant nephrotic syndrome: a multicentric study. J Am Soc Nephrol. 2004;15(7):1786-1792.
  • Larsen CP, et al. Collapsing glomerulopathy: a clinicopathologic study of 260 patients in the United States. Clin J Am Soc Nephrol. 2012;7(5):707-717.
• Reviews:
  • Noone D, et al. Genetic causes of steroid-resistant nephrotic syndrome. Pediatr Nephrol. 2016;31(11):1795-1815.
  • D'Agati VD, et al. Focal segmental glomerulosclerosis. N Engl J Med. 2016;374(16):1635-1647.
  • Hodson EM, et al. Interventions for idiopathic steroid-resistant nephrotic syndrome in children. Cochrane Database Syst Rev. 2018;12(12):CD003594.