Hypocalcemia may be associated with a spectrum of clinical manifestations, ranging from few if any symptoms if the hypocalcemia is mild and/or chronic, to severe life-threatening symptoms if it is severe and/or acute. Thus, the management of hypocalcemia depends upon the severity of symptoms. In patients with acute symptomatic hypocalcemia, intravenous calcium gluconate is the preferred therapy, whereas chronic hypocalcemia is treated with oral calcium and vitamin D supplements.
The treatment of hypocalcemia will be reviewed here. The etiology, clinical manifestations, and diagnostic approach to hypocalcemia are reviewed separately. (See "Etiology of hypocalcemia in adults" and "Clinical manifestations of hypocalcemia" and "Diagnostic approach to hypocalcemia".)
INTERPRETATION OF SERUM CALCIUM
Calcium in serum is bound to proteins, principally albumin. As a result, total serum calcium concentrations in patients with low or high serum albumin levels may not accurately reflect the physiologically important ionized (or free) calcium concentration. As an example, in patients with hypoalbuminemia, total serum calcium concentration may be low when serum ionized calcium is normal. The serum total calcium concentration falls approximately 0.8 mg/dL for every 1 g/dL reduction in the serum albumin concentration. Thus, in patients with hypoalbuminemia or hyperalbuminemia, the measured serum calcium concentration should be corrected for the abnormality in albumin (calculator 1) or for standard units (calculator 2).
If there is uncertainty whether the corrected serum calcium is reflective of the ionized calcium, and if a laboratory known to measure ionized calcium reliably is available, some authorities prefer to measure the ionized calcium directly. Direct measurement of the ionized calcium concentration could be considered in patients with symptoms of hypocalcemia in the setting of a normal total calcium concentration. Symptomatic hypocalcemia with normal total calcium but low ionized calcium can occasionally occur in patients with acute respiratory alkalosis due to increased binding of calcium to albumin. (See "Relation between total and ionized serum calcium concentration", section on 'Acid-base disorders'.)
In patients with asymptomatic hypocalcemia, it is important to verify with repeat measurement (ionized calcium or total serum calcium corrected for albumin) that there is a true decrease in the calcium concentration.