Hypocalcemia: Causes, Clinical features & Treatment

Ionized calcium level below 2.0 mEq/L or a total serum level below 8.5 mg/dL.

Causes of hypocalcemia: Shock, sepsis, renal failure, pancreatitis, hypomagnesemia, alkalosis, decreased serum albumin, hypoparathyroidism (idiopathic or as a result of irradiation or surgery), pseudo-hypoparathyroidism, osteoblastic metastasis, malabsorption, and excess phosphates.

CLINICAL FEATURES

1. Symptoms: Circumoral and distal extremity paresthesias, irritability, weakness, fatigue, muscle cramps, and seizures

2. Physical examination findings: Hyperreflexia, carpopedal spasm, tetany, laryngospasm, Trousseau sign (carpopedal spasm after arterial occlusion of the arm for 3 minutes), and Chvostek sign (contraction of the facial muscles after percussion over the facial nerve)

EVALUATION

1. Laboratory studies should include serum albumin, calcium, magnesium, phosphate, BUN, and creatinine levels; liver studies; amylase and lipase levels; ionized calcium levels; a serum electrolyte panel; and a CBC.

2. Electrocardiography: ECG findings may include a prolonged QT interval, sinus bradycardia, complete heart block, ventricular arrhythmias, and ventricular fibrillation.

3. Radiology: When hypocalcemia occurs in the context of osteomalacia, radiographic findings can include craniotabes, frontal skull bossing, rachitic rosary ribs, a widened rib cage (Harrison groove), bowed legs, demineralization, and thinning of the cortical bone.

THERAPY

1. Acutely symptomatic hypocalcemia: Administer 10 mL of 10% calcium gluconate infused intravenously over 10 to 15 minutes, followed by a maintenance infusion of 1 to 2 mg/kg/hour over 6 to 12 hours.

2. Asymptomatic: Oral therapy with elemental calcium (with or without vitamin D) may be all that is required. The rapid intravenous administration of calcium to asymptomatic patients with mild to moderate hypocalcemia is contraindicated because doing so can cause severe cardiovascular, neuromuscular, or renal complications.

DISPOSITION

1. Admission: Patients with symptomatic hypocalcemia who require intravenous replacement therapy must be admitted to the hospital. These patients should be placed on continuous cardiac monitoring, and serial serum calcium levels should be obtained.

2. Discharge: Asymptomatic patients may be discharged with appropriate follow-up.