Lhypercalcémie

Hypercalcemia, known in French as l'hypercalcémie, is defined as a higher-than-normal level of calcium in the blood. In adults, total serum calcium is typically 2.2–2.6 mmol/L (8.8–10.5 mg/dL); hypercalcemia is usually defined as above 2.6–2.75 mmol/L, depending on the laboratory reference range. It can be asymptomatic or associated with a variety of symptoms.

Most cases are due to primary hyperparathyroidism or cancer-related processes. Mechanisms include overproduction of parathyroid hormone (PTH) or PTH-related peptide (PTHrP), increased intestinal calcium absorption via excess vitamin D activity, osteolysis from bone metastases or immobilization, and certain drugs (thiazide diuretics, lithium).

Symptoms commonly include polyuria, polydipsia, constipation, nausea, neuropsychiatric symptoms, bone pain, and kidney stones. Milder forms may be discovered incidentally. Diagnosis involves measuring corrected calcium for albumin; measuring PTH. If PTH is elevated or inappropriately normal, primary hyperparathyroidism is considered; if suppressed, investigation focuses on malignancy, granulomatous disease, or vitamin D intoxication. Further tests may include PTHrP, 25(OH)D, 1,25(OH)2D, urinary calcium, and imaging guided by the suspected cause.

Treatment depends on severity and symptoms. Mild asymptomatic hypercalcemia may be observed with monitoring and treatment of the underlying disease. Acute or severe hypercalcemia requires aggressive hydration with isotonic saline, calcitonin for rapid partial relief, and bisphosphonates (pamidronate or zoledronic acid) for sustained reduction. Corticosteroids may help in vitamin D–mediated or granulomatous causes. Dialysis is used for patients with renal failure or refractory hypercalcemia.

Prognosis and epidemiology: hypercalcemia is common in older adults and in patients with cancer; prognosis is mainly driven by the underlying disease. Effective management relies on identifying and treating the underlying cause.