Determinants of parathyroid hormone levels in nursing home residents.

INTRODUCTION

Elevated parathyroid hormone (PTH) levels contribute to age-related bone loss. Practitioners should be aware of iatrogenic and/or correctable determinants of PTH elevation.

METHODS

We performed a cross-sectional study including 302 of 609 eligible residents at a state veterans home. Multiple regression analysis was used to determine the effect of 25-OH-D level, glomerular filtration rate (GFR), calcium supplements, diuretics, and mobility status on PTH levels. The dose of calcium carbonate and diuretics was determined as milligram per kilogram of body weight.

RESULTS

The multiple regression process identified GFR, 25-OH-D level, as well as the dose of furosemide and calcium per kilogram of body weight as significant contributors to PTH. In a 70-kg resident, a daily dose of 40 mg of furosemide was associated with an increase of 22.8 pg/mL in PTH, while 500 mg of elemental calcium carbonate (in the absence of a proton pump inhibitor) was associated with a decrease of 8.7 pg/mL in PTH. An increase of 10 ng/mL in 25-OH-D was associated with a decrease of 5.7 pg/mL in PTH.

DISCUSSION: Clinicians should be aware of the adverse effects of loop diuretics on urinary calcium excretion and PTH levels. Residents who ingest furosemide should be targeted to receive recommended doses of vitamin D and calcium.