Survival after the Diagnosis of Hyperparathyroidism: A Population-based Study

Background: Reports of increased mortality from cardiovascular disease and malignancy in primary hyperparathyroidism have been based primarily on patients who have undergone parathyroidectomy. In order to assess the true impact of primary hyperthyroidism on mortality in the general population, we assessed survival in a large inception cohort of Rochester, Minnesota residents with primary hyperparathyroidism initially diagnosed over a 28-year span, the majority of whom were followed with uncomplicated disease. Methods: All Rochester residents with primary hyperparathyroidism first recognized in 1965 to 1992 were identified through the Rochester Epidemiology Project medical records linkage system. Included as cases were patients with pathologic confirmation of hyperthyroidism, hypercalcemia with inappropriately elevated parathyroid hormone levels, or hypercalcemia for more than a year with no other cause. Survival was estimated using the Kaplan Meier product-limit method. The Cox proportional hazards model was used to determine associations, as relative hazards (RR) with 95% confidence intervals (CI), of various risk factors with time to death. Results: During the study period, 435 cases of primary hyperparathyroidism were identified. Altogether, parathyroid surgery was performed on 126 patients (29%), with a mean delay between the initial elevated serum calcium level and surgery of 3.3 years. Patients who underwent surgery had higher maximum serum calcium levels than the patients who were observed (mean ± SD, 11.3 ± 0.7 versus 10.7 ± 0.4 mg/dL, P