What are the symptoms and treatment of hypocalcemia?

Hypocalcemia: Symptoms and Treatment

Clinical Manifestations

Hypocalcemia presents with a spectrum of neuromuscular, cardiovascular, and neuropsychiatric symptoms that range from mild paresthesias to life-threatening cardiac arrhythmias and seizures. 1

Neuromuscular Symptoms

• Paresthesias (tingling/numbness) of hands, feet, and perioral region are the most common early manifestations 1
• Muscle cramps and spasms occur frequently and may progress to tetany with focal or generalized tonic muscle contractions 1, 2
• Tetany represents the hallmark of acute hypocalcemia (ionized calcium <0.75 mmol/l) and is characterized by severe neuromuscular irritability 2
• Laryngospasm can occur in severe cases and represents a medical emergency 2
• Seizures may be the first presenting sign, particularly in patients with underlying seizure disorders 1

Cardiovascular Manifestations

• Prolonged QT interval on electrocardiogram is a common and important finding 1, 2
• Cardiac arrhythmias, including ventricular tachycardia and fibrillation, can occur and may be life-threatening 1
• Myocardial dysfunction may develop in severe cases 2
• Cardiomyopathy is a rare but serious complication of chronic hypocalcemia 1

Neuropsychiatric Symptoms

• Confusion or altered mental status can occur with severe hypocalcemia 1
• Irritability and emotional changes are common neurological manifestations 1
• Behavioral changes such as anxiety or depression may be present and can be confused with primary psychiatric conditions 1, 3
• Fatigue is a frequent but nonspecific symptom 1

Diagnostic Approach

Essential Laboratory Tests

• Measure pH-corrected ionized calcium (most accurate method) to confirm hypocalcemia 1, 3
• Check magnesium levels in ALL hypocalcemic patients, as hypomagnesemia must be corrected first before calcium normalization can occur 4, 3
• Measure parathyroid hormone (PTH) levels to determine if hypoparathyroidism is present 1
• Assess renal function (creatinine) to evaluate for kidney disease 1
• Check vitamin D status (25-OH vitamin D levels) 1
• Monitor thyroid function, as hypothyroidism may be associated with hypocalcemia 1

Critical Diagnostic Pitfall

Less than 1% of the body's total magnesium is in extracellular fluids, so patients can have magnesium deficiency despite normal serum concentrations. 4 Always verify magnesium levels in hypocalcemic patients, as calcium administration will be ineffective without first correcting magnesium deficiency 4.

Treatment

Acute Symptomatic Hypocalcemia

For severe, symptomatic hypocalcemia, begin with intravenous calcium administration immediately. 1

Intravenous Calcium Protocol

• Administer 10% calcium chloride (contains 270 mg elemental calcium per 10 mL) for severe cases 1
• Alternatively, use 100-200 mg of elemental calcium as calcium gluconate intravenously 2
• Monitor cardiac rhythm continuously during rapid calcium administration due to arrhythmia risk 1, 5
• Administer via central venous catheter when possible to avoid extravasation complications 6

Magnesium Correction (If Hypomagnesemia Present)

The European Society of Cardiology recommends NOT administering calcium without first correcting magnesium, as it will be ineffective. 4

• Administer 1-2 g magnesium sulfate IV bolus for symptomatic acute hypocalcemia with hypomagnesemia 4
• Calcium normalization requires approximately 4 days after initiating magnesium therapy, even though PTH levels normalize within 24 hours 4
• Magnesium supplementation is necessary if hypomagnesemia is present 4

Chronic Hypocalcemia Management

First-Line Oral Therapy

• Start with oral calcium salts (calcium carbonate is most commonly used and provides highest elemental calcium content per dose) with total elemental calcium intake not exceeding 2,000 mg/day 1
• Combine calcium with vitamin D, as this combination is more effective than either agent alone 1
• Correct vitamin D deficiency with native vitamin D (cholecalciferol or ergocalciferol) supplementation 1

Active Vitamin D Metabolites (For Hypoparathyroidism)

• Initial calcitriol dose: 20-30 ng/kg body weight daily, or alternatively start with 0.5 μg daily in patients >12 months old 1
• Alfacalcidol: 30-50 ng/kg body weight daily as alternative 1
• These should be prescribed under endocrinologist guidance 1

Monitoring Requirements

During Treatment

• Measure serum calcium and phosphorus at least every 3 months during chronic treatment 1, 4
• Monitor for hypercalciuria to prevent nephrocalcinosis, especially when using active vitamin D metabolites 1
• Discontinue vitamin D therapy if serum calcium exceeds 10.2 mg/dL (2.54 mmol/L) to avoid hypercalcemia 1
• Maintain calcium-phosphorus product <55 mg²/dL to prevent metastatic calcification 1
• If serum phosphorus exceeds 4.6 mg/dL, add or increase phosphate binders before continuing vitamin D therapy 1

High-Risk Periods Requiring Targeted Monitoring

• Surgery, childbirth, or infection increase hypocalcemia risk significantly 1, 3
• Perioperative periods, acute illness, puberty, and pregnancy are vulnerable times requiring close calcium monitoring 1, 3

Critical Pitfalls and Considerations

Treatment Complications

• Overcorrection of calcium can lead to hypercalcemia, renal calculi, and renal failure 1, 4
• Keep calciuria levels within normal range when administering calcium supplements to prevent nephrocalcinosis 1

Drug Interactions

• Avoid calcium administration in patients receiving cardiac glycosides (digoxin), as hypercalcemia increases digoxin toxicity risk 5
• If necessary, administer calcium slowly in small amounts with continuous ECG monitoring 5
• Calcium may reduce response to calcium channel blockers 5

Special Populations

• Patients with 22q11.2 deletion syndrome have 80% lifetime prevalence of hypocalcemia 1, 3
• Neonates (≤28 days): Concomitant use of ceftriaxone and calcium gluconate is contraindicated due to fatal ceftriaxone-calcium precipitate formation 5
• Patients receiving multiple blood transfusions: Monitor calcium closely due to citrate-induced hypocalcemia 1
• Renal impairment: Initiate at lowest recommended dose and monitor serum calcium every 4 hours 5

Precipitating Factors to Avoid

• Alcohol consumption worsens hypocalcemia 1, 3
• Carbonated beverages, especially colas, may exacerbate hypocalcemia 1, 3
• Decreased oral calcium intake contributes to hypocalcemia 3