Hypercalcemia

Hypercalcemia is a condition in which the calcium level in the blood is elevated above the normal range. In adults, total serum calcium is typically about 8.5–10.5 mg/dL (2.12–2.62 mmol/L); ionized calcium is measured separately when precise assessment is needed. Calcium balance is governed by parathyroid hormone, vitamin D, and renal excretion; hypercalcemia arises from increased bone resorption, increased intestinal absorption, or decreased renal excretion.

Common causes include primary hyperparathyroidism, malignancy (including humoral hypercalcemia of malignancy from PTH-related peptide and bone metastases), vitamin D intoxication or granulomatous disease, medications (such as thiazide diuretics or lithium), immobilization, and renal failure. The relative frequency varies by setting: primary hyperparathyroidism is most common in outpatient contexts, while cancer is a leading cause of severe cases.

Symptoms range from asymptomatic to life-threatening and may include fatigue, polyuria, polydipsia, constipation, nausea, confusion, and weakness. The classic description is “stones, bones, groans, and psychic overtones,” reflecting various presentations.

Diagnosis involves confirming elevated calcium and correcting for albumin if needed, then measuring parathyroid hormone (PTH). A high or inappropriately normal PTH with hypercalcemia suggests primary hyperparathyroidism; suppressed PTH with hypercalcemia points to non-PTH-mediated causes such as malignancy. Additional tests may include PTH-related peptide, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D to guide further workup.

Management focuses on treating the underlying cause and correcting calcium. Acute treatment includes aggressive IV hydration and, if indicated, calcitonin for rapid but temporary effect; longer-term reduction can be achieved with bisphosphonates or denosumab. Severe or refractory cases may require dialysis. Prognosis depends on the underlying etiology.