What is the treatment for hypocalcemic tetany?

Treatment of Hypocalcemic Tetany

For symptomatic hypocalcemic tetany, immediately administer intravenous calcium gluconate 50-100 mg/kg (or 1-2 grams in adults) infused slowly over 10-30 minutes with continuous cardiac monitoring, followed by a continuous calcium infusion if symptoms persist. 1, 2

Immediate Management

Initial Calcium Administration

• Administer calcium gluconate 10% solution: 10-20 mL (1-2 grams) IV over 10-30 minutes in adults 2, 3
• For pediatric patients: calcium gluconate 50-100 mg/kg IV administered slowly 1, 2
• Calcium chloride is an alternative (preferred in critical care settings): 5-10 mL of 10% solution IV over 2-5 minutes in adults, or 20 mg/kg (0.2 mL/kg) in children 2, 4
• Calcium chloride contains 270 mg elemental calcium per 10 mL versus only 90 mg in calcium gluconate, making it more potent 2
• Continuous cardiac monitoring is mandatory during administration; stop infusion if symptomatic bradycardia occurs 2, 3

Continuous Infusion for Persistent Symptoms

• If tetany persists after initial bolus, start continuous calcium infusion at 1-2 mg elemental calcium/kg/hour 2
• Adjust infusion rate to maintain ionized calcium in normal range (1.15-1.36 mmol/L or 1.1-1.3 mmol/L) 2
• Monitor ionized calcium levels every 4-6 hours initially until stable, then twice daily 2

Critical Administration Details

• Use central venous access for sustained infusions to avoid severe tissue injury from extravasation 2, 3
• Never mix calcium with sodium bicarbonate—it causes precipitation 2
• Infuse slowly to prevent cardiac arrhythmias 2, 3

Essential Cofactor Correction

Magnesium Replacement

• Check serum magnesium immediately—hypomagnesemia is present in 28% of hypocalcemic ICU patients and prevents calcium correction 2
• Hypocalcemia cannot be fully corrected without adequate magnesium 2, 5
• Administer IV magnesium sulfate for replacement if deficient 2

Transition to Maintenance Therapy

Oral Calcium Supplementation

• Once ionized calcium stabilizes and oral intake is possible, transition to calcium carbonate 1-2 grams three times daily 2
• Total elemental calcium intake (dietary plus supplements) should not exceed 2,000 mg/day 1, 2

Vitamin D Therapy

• Add calcitriol up to 2 μg/day to enhance intestinal calcium absorption 2
• Note that vitamin D or dihydrotachysterol do not correct hypocalcemia immediately—effects may be delayed 15-25 days 5
• Measure 25-hydroxyvitamin D levels; if <30 ng/mL, plan vitamin D supplementation once acute phase is managed 2

Additional Considerations for Chronic Management

• In CKD patients with PTH >300 pg/mL, active vitamin D sterols are indicated 2
• Target corrected total serum calcium in the low-normal range (8.4-9.5 mg/dL or 2.10-2.37 mmol/L) to minimize hypercalciuria and renal dysfunction 1, 2

Monitoring and Follow-Up

• Continue monitoring ionized calcium until consistently stable in normal range 2
• Once stable, monitor corrected total calcium and phosphorus at least every 3 months 2
• If patient was previously on phosphate binders, reduce or discontinue based on serum phosphorus levels 2

Critical Pitfalls to Avoid

Alkalosis Exacerbates Hypocalcemia

• Correction of acidosis may worsen hypocalcemia because acidosis increases ionized calcium levels 2
• A 0.1 unit increase in pH decreases ionized calcium by approximately 0.05 mmol/L 2
• Alkalosis reduces the amount of calcium in ionized form and increases calcium bicarbonate complexing 6

Drug Interactions

• Avoid calcium administration with cardiac glycosides (digoxin)—hypercalcemia increases digoxin toxicity and synergistic arrhythmias may occur 3
• Calcium may reduce response to calcium channel blockers 3
• Concomitant cimetidine and nifedipine can precipitate severe hypocalcemic tetany 7

Special Clinical Contexts

• In tumor lysis syndrome, exercise extreme caution with calcium administration—only treat symptomatic patients and consider renal consultation if phosphate levels are elevated 1, 2
• Asymptomatic hypocalcemia in tumor lysis syndrome does not require treatment 1
• During massive transfusion, hypocalcemia results from citrate-mediated chelation; maintain ionized calcium >0.9 mmol/L minimum 2

Pediatric Considerations

• Concomitant use of ceftriaxone and calcium gluconate is contraindicated in neonates ≤28 days due to fatal ceftriaxone-calcium precipitates in lungs and kidneys 3
• In patients >28 days, these drugs may be given sequentially with thorough line flushing between infusions 3

Underlying Cause Assessment

• Check PTH levels—secondary hyperparathyroidism may be contributing in renal impairment 2
• Assess for symptoms: paresthesias, Chvostek's and Trousseau's signs, bronchospasm, laryngospasm, seizures, or cardiac arrhythmias 1, 2
• Hypocalcemic tetany is rarely life-threatening in adults but requires prompt treatment to prevent progression 5, 8