Clinical significance of hyperparathyroidism in familial multiple endocrine adenomatosis type I (MEA I).

In order to investigate the suggestion that hyperparathyroidism in patients with familial MEA I has a mild and nonprogressive clinical course, we have compared clinical, biochemical, roentgenologic and histologic features of 29 patients with hyperparathyrodism originating from six families with the MEA I syndrome with those of 28 unselected patients with isolated nonfamilial hyperparathyroidism. The patients from the families with MEA I were significantly younger, had lower serum calcium and inorganic phosphate concentrations and a lower incidence of elevated alkaline phosphatase levels. Furthermore, they had multiple enlarged parathyroid glands and recurrence of the disease significantly more often. There was, however, no significant difference in the incidence of renal impairment, urolithiasis, subperiosteal resorption or large bone cysts on roentgenograms, histologic changes in bone biopsy specimens or mortality due to hyperparathyroidism. Therefore, the suggestion that this type of hyperparathyroidism has a milder clinical course is not confirmed in the present study.