Coexisting thyroid and parathyroid disease--are they related?

A high prevalence of non-C cell, thyroid gland disease associated with primary hyperparathyroidism (HPT) has been reported in 11 uncontrolled studies. Yet experimental evidence linking these thyroid and parathyroid gland lesions is lacking. To test the hypothesis that the coexistence of these lesions is significant, we analyzed 124 consecutive cases of parathyroidectomy (110 women, mean age 53.5 +/- 12.7 years). Patients in the group with HPT who had visible or palpable thyroid disease at the time of operation were age-, sex-, and race-matched with autopsy controls. There was no statistical difference in the prevalence of total macroscopic thyroid lesions between the autopsy control group (46.4%) and the group of patients with HPT (54%, P = 0.8). Microscopic lesions in the absence of macroscopic abnormalities were found in an additional 26% of the autopsy control patients. Since in the surgical group, only those with macroscopic abnormalities underwent thyroid biopsy, no accurate calculation can be made of the microscopic lesions in those 55 patients with HPT who did not have macroscopic abnormalities. There was no difference in the prevalence of autoimmune or thyroid nodular disease between the two groups except for the presence of seven macroscopic nonmedullary thyroid carcinomas in the HPT group and none in the autopsy control group (P less than 0.001). One microscopic carcinoma was found in the autopsy group, however. An increased prevalence of parathyroid adenomas in nonmedullary thyroid disease has been suggested by other studies. We were unable to confirm this association. In fact, the incidence of parathyroid adenomas found unsuspectedly in 229 consecutive thyroidectomies was 0.43%. Thus with the exception of macroscopic, nonmedullary carcinomas, there was no evidence that thyroid disease accompanies HPT. Furthermore, parathyroid adenomas were not more frequent in surgical thyroid disease. Lesions of the thyroid and parathyroid glands are prevalent in middle-age women. This probably is the major factor that accounts for their coexistence.