featureshypercalcemia

Hypercalcemia refers to an elevated level of calcium in the blood. It is often defined as a total serum calcium above about 10.5 mg/dL (2.62 mmol/L), with ionized calcium providing the most clinically relevant measure in some cases. Many individuals are asymptomatic, but when symptoms occur they typically involve the nervous system, kidneys, gastrointestinal tract, and cardiovascular system.

Common features include fatigue, weakness, confusion or mood changes, and decreased concentration. Gastrointestinal symptoms such as nausea, vomiting, abdominal pain, constipation, and loss of appetite may appear. Polyuria and polydipsia due to renal concentrating defects are frequent, and dehydration can develop. In more severe or prolonged cases, patients may experience marked lethargy, cognitive impairment, coma, or pancreatitis. Cardiac effects can include a shortened QT interval on electrocardiography and, in extreme cases, arrhythmias.

Etiologies are diverse. Primary hyperparathyroidism and familial hypocalciuric hypercalcemia are examples of PTH-mediated hypercalcemia. PTH-independent cases include malignancy-associated hypercalcemia (often via PTH-related peptide), vitamin D–mediated hypercalcemia from granulomatous diseases or certain lymphomas, and medication-related causes (e.g., thiazide diuretics, lithium). Immobilization and excessive calcium or vitamin D intake can contribute in some individuals.

Diagnostic approach centers on measuring corrected or ionized calcium and assessing PTH. If PTH is elevated or inappropriately normal, PTH-related investigations for primary, familial, or other PTH-mediated causes are pursued. If PTH is suppressed, evaluation focuses on malignancy, vitamin D–mediated processes, and other secondary causes.