Hypercalcaemia in hospital patients. Clinical and diagnostic aspects.

The relative importance of different causes of hypercalcaemia was studied, and diagnostic tests were evaluated as predictors of the cause of hypercalcaemia. In one year, hypercalcaemia was identified in 166 hospital inpatients. Serum-calcium was below 3.00 mmol/l in 63%. Among 153 patients investigated the commonest cause of hypercalcaemia was malignancy (89 cases), especially breast and bronchial tumours. 75% of the 89 patients had obvious metastases at presentation. 51 patients had primary hyperparathyroidism: their symptoms were non-specific and only 20% had renal stones. Other causes of hypercalcaemia were rare (9% of patients seen). Of patients with no diagnosis initially, 64% had hyperparathyroidism and 32% malignancy, but this was demonstrated early in the illness. Serum phosphate and chloride and acid/base status were unsatisfactory as diagnostic tests; multivariate analysis was more discriminating overall, but incorrect classification was still a significant problem.