Calcium

# calcium ## Overview - **Classification**: Macro-mineral, Electrolyte - **Mechanism**: Essential for bone formation, nerve impulse transmission, muscle contraction, and blood coagulation. It maintains cell membrane integrity and acts as a secondary messenger. ## Primary Indications 1. **Hypocalcemia**: Treatment of acute or chronic low serum calcium levels. 2. **Osteoporosis/Osteopenia**: Prevention and treatment in conjunction with Vitamin D. 3. **Dietary Supplementation**: To meet daily calcium requirements. 4. **Antacid**: Calcium carbonate can neutralize stomach acid (less common primary use). ## Adult Dosing ### Standard Dosing **Acute Hypocalcemia (e.g., symptomatic, severe)** - **Dose**: **1000-2000 mg** Calcium Gluconate IV (or **500-1000 mg** Calcium Chloride IV) - **Frequency**: Administer slow IV push over **10-20 minutes**. May repeat q6h as needed. - **Route**: Intravenous (IV) - **Max Dose**: Typically **3-4 g/day** Calcium Gluconate IV. - **Special Considerations**: Calcium Chloride provides more elemental calcium per volume but is more irritating; central line preferred. **Chronic Hypocalcemia / Dietary Supplementation / Osteoporosis** - **Dose**: **1000-1200 mg** elemental calcium - **Frequency**: Daily, divided into 2-3 doses (e.g., **500-600 mg BID**) - **Route**: Oral - **Special Considerations**: Calcium carbonate should be taken with food for optimal absorption. Calcium citrate can be taken with or without food. **Antacid (Calcium Carbonate)** - **Dose**: **500-1500 mg** elemental calcium - **Frequency**: As needed, up to **3-4 times daily** - **Route**: Oral - **Max Dose**: Typically **2500 mg/day** elemental calcium for antacid use. ### Dose Adjustments - **Renal Impairment**: Use with caution. Monitor serum calcium, phosphate, and magnesium closely. Avoid excessive doses, especially with calcium carbonate due to hypercalcemia risk. - **Hepatic Impairment**: No specific dose adjustment generally needed. - **Elderly Patients**: No specific dose adjustment beyond general adult dosing, but monitor for hypercalcemia due to potential reduced renal clearance. ## Pediatric Dosing ### Neonates (0-28 days) **Acute Hypocalcemia** - **Dose**: **100-200 mg/kg/dose** Calcium Gluconate IV (equivalent to 9-18 mg/kg elemental Ca) - **Frequency**: Administer over **5-10 minutes**. May repeat PRN or follow with infusion. - **Maintenance Infusion**: **500-1500 mg/kg/day** Calcium Gluconate IV, continuous infusion or divided q6h. - **Maximum**: **3 g/day** Calcium Gluconate IV. - **Special Notes**: Slow IV administration is crucial to prevent bradycardia. Monitor heart rate during infusion. ### Infants (1-12 months) **Acute Hypocalcemia** - **Dose**: **100 mg/kg/dose** Calcium Gluconate IV (equivalent to 9 mg/kg elemental Ca) - **Frequency**: Administer over **5-10 minutes**. May repeat q6-8h PRN. - **Maintenance Infusion**: **500-1500 mg/kg/day** Calcium Gluconate IV, continuous infusion or divided q6h. - **Maximum**: **3 g/day** Calcium Gluconate IV. - **Oral Supplementation**: **50-100 mg/kg/day** elemental calcium, divided 3-4 times daily. ### Children (1-12 years) **Acute Hypocalcemia** - **Dose**: **100 mg/kg/dose** Calcium Gluconate IV (equivalent to 9 mg/kg elemental Ca) - **Frequency**: Administer over **5-10 minutes**. May repeat q6-8h PRN. - **Maintenance Infusion**: **500-1500 mg/kg/day** Calcium Gluconate IV, continuous infusion or divided q6h. - **Maximum**: **3 g/day** Calcium Gluconate IV. - **Oral Supplementation**: **50-100 mg/kg/day** elemental calcium, divided 3-4 times daily. - **Maximum Oral**: **1-3 g/day** elemental calcium. ### Adolescents (13-18 years) - **Dose**: Dosing generally follows adult recommendations for both IV and oral forms. - **Maximum**: Adult maximums typically apply, e.g., **3 g/day** IV Calcium Gluconate; **2500 mg/day** elemental calcium orally. ## Safety Information ### Contraindications - **Absolute**: Hypercalcemia, severe hypercalciuria. - **Absolute**: Ventricular fibrillation (IV calcium). - **Relative**: Renal calculi (history of), digitalis toxicity (IV calcium). ### Common Adverse Effects - **Very Common (>10%)**: Constipation (oral), GI upset/bloating (oral). - **Common (1-10%)**: Nausea, dry mouth. - **Serious but Rare**: Hypercalcemia (especially with high doses or renal impairment), IV site irritation/extravasation, cardiac arrhythmias (rapid IV push). ### Key Drug Interactions - **Digoxin**: Increased risk of digitalis toxicity, especially with IV calcium. Avoid concomitant IV administration. - **Tetracyclines/Fluoroquinolones**: Calcium chelates these antibiotics, reducing absorption. Separate administration by **2-6 hours**. - **Thyroid Hormones (Levothyroxine)**: Calcium can reduce absorption. Separate administration by at least **4 hours**. - **Bisphosphonates**: Reduced absorption of bisphosphonates. Separate administration by **30-60 minutes**. - **Iron Supplements**: Calcium can inhibit iron absorption. Separate by **2 hours**. - **Thiazide Diuretics**: Can decrease renal calcium excretion, increasing hypercalcemia risk. Monitor calcium levels. ## Monitoring & Follow-up - **Before Treatment**: Baseline serum calcium (total and ionized), albumin, phosphate, magnesium, renal function (CrCl). - **During Treatment**: Serum calcium (total and ionized) regularly, especially with IV administration (e.g., q4-6h initially). Monitor renal function, phosphate, and magnesium periodically. - **Clinical Signs**: Watch for signs of hypercalcemia (nausea, vomiting, constipation, polyuria, weakness, confusion) or hypocalcemia (muscle cramps, paresthesias, tetany, seizures). Monitor IV site for extravasation. ## Clinical Pearls - 💡 **Absorption**: Calcium carbonate requires stomach acid for optimal absorption; take **with food**. Calcium citrate is acid-independent and can be taken without food. - 💡 **IV Administration**: Administer IV calcium slowly to avoid hypotension, bradycardia, and cardiac arrhythmias. Dilute IV calcium for peripheral administration to reduce vein irritation. - 💡 **Elemental Calcium**: Always consider the elemental calcium content when dosing oral supplements (e.g., calcium carbonate is ~40% elemental, calcium citrate ~21%). - 💡 **Vitamin D**: Adequate Vitamin D levels are crucial for calcium absorption and utilization; co-supplementation is often necessary. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.