[Epidemiology of hypercalcemia. Significance of the determination of intact parathyroid hormone for differential diagnosis].

Serum-calcium levels were determined in 9666 hospital inpatients during one year. Hypercalcaemia was present in 101 patients (51 women, 50 men, mean age 57 years). In 46 patients, hypercalcaemia was caused by malignancy. The second commonest cause was primary hyperparathyroidism (pHPT) in 35 cases. In the other 20 patients, hypercalcaemia was related to thiazid medication (8 patients), elevated 25-hydroxy-vitamin-D3-levels (six patients) or immobilisation (two patients). In four patients, no cause was found. Intact parathyroid hormone levels reliably distinguished patients with pHPT (values greater than 60 ng/l) from patients with hypercalcaemia of other causes (values less than 40 ng/l). Other laboratory tests were less useful. Serum-calcium levels greater than 2.9 mmol/l were found only in pHPT and hypercalcaemia of malignancy. In pHPT, the medical history frequently revealed nephrolithiasis (12 patients) and gastrointestinal ulcers (8 patients), whereas weight loss was far more common in hypercalcaemia of malignancy (28 patients).