Body Size and the Risk of Primary Hyperparathyroidism in Women: A Cohort Study

Greater body weight and fat mass have been associated with higher serum parathyroid hormone levels and a higher prevalence of primary hyperparathyroidism (P-HPTH) in women. However, prospective studies to evaluate whether greater body size associates with a higher incidence of developing P-HPTH have not been reported. We investigated whether greater body size was independently associated with a higher risk for developing P-HPTH in women. We conducted a prospective cohort study of 85,013 female participants in the Nurses' Health Study I followed for up to 26 years. Body size was measured via multiple metrics: weight, body-mass index (BMI), and waist circumference (WC). Weight and BMI were assessed every two years from 1986 to 2012, and WC was assessed in 1986, 1996, and 2000. Detailed dietary and demographic exposures were quantified via validated biennial questionnaires. Incident cases of P-HPTH were confirmed by individual medical record review. Cox proportional hazards models were used to evaluate whether WC, weight, and BMI were independent risk factors for developing P-HPTH. Models were adjusted for demographic variables, comorbidities, medications, intakes of calcium and vitamin D, and exposure to ultraviolet light. We confirmed 491 incident cases of P-HPTH during 2,128,068 person-years of follow-up. The multivariable adjusted relative risks for incident P-HPTH increased across quartiles of WC: Q1: ref, Q2: 1.34 (0.97, 1.86), Q3: 1.70 (1.24, 2.31), Q4: 2.27 (1.63, 3.18), P-trend < 0.001. Similarly, the multivariable adjusted risks for incident P-HPTH increased across quartiles of weight: Q1: ref, Q2: 1.23 (0.92, 1.65), Q3: 1.63 (1.24, 2.14), Q4: 1.65 (1.24, 2.19), P-trend < 0.001. A similar but statistically non-significant trend was observed across quartiles of BMI (P-trend = 0.07). In summary, body size may be an independent and modifiable risk factor for developing P-HPTH in women. This article is protected by copyright. All rights reserved