Primary hyperparathyroidism. Changing clinical spectrum, prevalence of hypertension, and discriminant analysis of laboratory tests.

The clinical spectrum of 100 consecutive cases of surgically proved primary hyperparathyroidism treated from 1974 through 1978 was analyzed. Their laboratory test results were compared with 64 cases of other form of hypercalcemia using multivariate discriminant analysis. The clinical spectrum has dramatically shifted during the past three decades from renal calculi and bone disease to the asymptomatic patient discovered by routine serum chemical analysis. Hypertension was twice as common among hyperparathyroid patients as in the general population but failed to improve in 92% after parathyroidectomy. The most useful discriminant laboratory test in descending order of value were the serum chloride, serum calcium, hematocrit, serum phosphorus, and parathormone. Multivariate discriminant analysis of the serum calcium, phosphorus, chloride, and Hct provided a 98% degree of accuracy in separating hyperparathyroidism from other forms of hypercalcemia.