Longitudinal Assessment of PTH in Community-Dwelling Older Women—Elevations Are Not Associated With Mortality

Context In older women, the magnitude of elevated parathyroid hormone (PTH) and its consequence is unclear. Objective To describe normal PTH profiles over time and the association with mortality. Design and Participants There were 1044 community-dwelling women in the Malmö Osteoporosis Prospective Risk Assessment cohort (OPRA) who attended baseline (age 75 years). Follow-ups were attended by 715 (age 80 years) and 382 (age 85 years). Main Outcome Measures PTH, estimated glomerular filtration rate (eGFR), 25-hydroxyvitamin D (25OHD) and mortality. Results At age 75 years, PTH levels for most (n = 877, 88%) were within the normal reference range (NRR) (i.e., <6.9 pmol/L). Longitudinally, between ages 75 and 80 years, PTH increased in 60% of all women (n = 390) but increases of up to 50% above baseline values (64%; n=250) still resulted in PTH levels within the NRR. These women had lower 25OHD levels (74 vs 83 nmol/L, P = 0.001). Only when increases were >50% was PTH elevated beyond the NRR (mean 7.1 ± 3.3). Here, a pronounced decline in eGFR (56 vs 61 mL/min/1.73 m2, P = 0.002) was found, despite no further changes in 25OHD. Extending the observational period until age 85 years gave similar results. Baseline PTH levels above NRR were associated with mortality (hazard ratio, 1.4; 95% confidence interval (CI), 1.1-1.8; P = 0.007), although not after adjustment for covariates (P = 0.082). Conclusions Most women remained within normal PTH ranges despite large increases of up to 50%. PTH elevated above normal is not independently associated with mortality; impaired kidney function and low 25OHD status may be more prognostic in the very old.