Physical activity and the risk of primary hyperparathyroidism

Abstract

Context: Primary hyperparathyroidism (P-HPTH) is relatively common and predominantly affects women. Prior studies have shown that physical activity (PA) can lower PTH levels. Objective: Our objective was to evaluate the hypothesis that lower PA is a risk factor for developing P-HPTH. Design, Setting, and Participants: This prospective cohort study included 69 621 female participants in the Nurses' Health Study I followed for 22 years. Exposures: PA and other dietary and demographic exposures were quantified via detailed, and validated, biennial questionnaires. Outcomes: Incident P-HPTH was confirmed by medical record review after initial assessment by questionnaire. Adjusted Cox proportional hazards models were used to evaluate whether PA was an independent risk factor for developing P-HPTH. We also evaluated the risk of developing P-HPTH when combining low PA (<16 metabolic equivalent hours/week) with a previously identified independent risk factor for developing P-HPTH: low calcium intake (<800 mg/day). The relation between PA and PTH levels was evaluated in 625 participants. Results: We confirmed 302 incident cases of P-HPTH during 1 474 993 person-years of follow-up. Participants in the highest quintile (Q) of PA had a 50% lower risk of developing P-HPTH: age-adjusted relative risks and 95% confidence intervals for incident P-HPTH by lowest to highest of PA were Q1 = 1.0 (reference); Q2 = 0.83 (0.60-1.15); Q3 = 0.84 (0.61-1.15); Q4 = 0.50 (0.34-0.74); Q5 = 0.50 (0.35-0.73); P for trend