RISK OF AGE-RELATED FRACTURES IN PATIENTS WITH PRIMARY HYPERPARATHYROIDISM

Background.-Bone mass is reduced, but the influence of primary hyperparathyroidism (HPT) on fracture risk is controversial. We addressed this issue in a population-based retrospective cohort study. Methods.-Ninety residents of Rochester, Minn, were first diagnosed with HPT in 1965 through 1976 and an equal number of age- and sex-matched control subjects from the community were identified. Fractures were assessed through review of each subject's complete (inpatient and outpatient) medical records in the community. Results.-Prior to the date of diagnosis, Rochester residents with HPT were more likely to have a history of fractures than were matched control subjects from the same population (30% vs 18%). Subsequently, 36% of cases and 31% of control subjects experienced one or more new fractures during 1072 person-years of follow-up; survival free of a new fracture was almost the same in the two groups. Women had more fractures than men, and fracture rates increased with age. Fractures appeared to be somewhat more frequent in those with baseline serum calcium levels of 2.74 mmol/L or more, in those with comorbid conditions possibly due to HPT and in those who did not undergo parathyroidectomy, but these differences were not statistically significant. In a multivariate analysis, only age at diagnosis was an independent predictor of fracture risk, with a 36% increase in risk per 10-year increase in age. Conclusions.-Overall fracture risk was increased prior to diagnosis of HPT but not afterward. Because the numbers involved were small, however, we cannot exclude an increased likelihood of fractures in certain subgroups of HPT patients.