Evaluation of the hypercalcemic patient.

Malignancy is the most common cause of hypercalcemia, which may result from direct involvement of bone or from local or distant production of substances that enhance bone resorption. The recognized incidence of primary hyperparathyroidism has increased greatly since the advent of automated biochemical screening. A single parathyroid adenoma is most frequently the cause. Sarcoidosis commonly results in hypercalciuria but seldom causes sustained hypercalcemia. Increased production of 1,25-dihydroxycholecalciferol leads to hyperabsorption of calcium and enhanced bone resorption.