Approccio al paziente con ipercalcemia

Hypercalcaemia is a clinical condition characterised by serum calcium levels two standard deviations above the normal average. Although usually total calcium is the parameter tested, measurement of ionised calcium is the most reliable tool because it is not influenced by albumin levels that may be impaired in different clinical scenarios. However, in many laboratories measurement of ionised calcium is not available, and a formula can be used to calculate albumin-adjusted serum calcium levels. Mild hypercalcaemia is defined as serum calcium levels between 10.5 and 12 mg/dL, moderate between 12 and 14 mg/dL and severe for values above 14 mg/dL. Mild hypercalcaemia is often asymptomatic. Conversely, moderate and severe hypercalcaemia are usually associated with clinical manifestations affecting different tissues, especially the kidney (lithiasis, nephrocalcinosis, impairment of glomerular filtration), the bones (osteoporosis) and the heart (arrhythmias). Once hypercalcaemia has been confirmed, a correct differential diagnosis is mandatory. Detection of PTH levels is useful to distinguish between PTH-dependent hypercalcaemia (namely, primary hyperparathyroidism) and PTH-independent forms (namely, hypercalcaemia of malignancy). Normally, mild hypercalcaemia does not require emergency treatment. In moderate or severe forms, patient safety is secured through rapid reduction of serum calcium levels. Intravenous hydration is the most effective tool, in association with specific drugs.