Incidence of hypercalcaemia and primary hyperparathyroidism in relation to the biochemical profile.

Over a period of one year, 24500 patients underwent a biochemical profile investigation. Seven hundred and thirty-eight (3%) patients had a plasma calcium concentration of greater than 2.60 mmol/l, and hypercalcaemia was confirmed in 49.8% of those subjects from whom a second fasting sample was received. Primary hyperparathyroidism and malignant disease were the two commonest causes of hypercalcaemia, occurring with equal frequency. The overall incidence of primary hyperparathyroidism in our population was 1:680. Over 75% of the patients with primary hyperparathyroidism appeared to have asymptomatic disease. The merits of including a plasma calcium determination in a biochemical profile would seem to depend particularly on the natural history of asymptomatic primary hyperparathyroidism.