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.

Determinants of vitamin D levels in nursing home residents.

OBJECTIVE: To determine the effect of various doses of vitamin D(2) and D(3), as well as ambulatory status (a surrogate for sun exposure), on 25-OH-D levels. DESIGN: Cross-sectional study with multiple regression analysis. SETTING: A state veterans home for veterans and their spouses. PARTICIPANTS: Three hundred two of 609 eligible residents. MEASUREMENTS: Serum 25-OH-D and parathyroid hormone (PTH) level, supplemental dose of vitamins D(2) and D(3) per kilogram of body weight, and 3 levels of ambulatory status. RESULTS: The mean 25-OH-D level was 28.6 + 9.2 ng/mL; 6.6% of subjects had values of 16 ng/mL or below. Thirty-two percent of participants had 25-OH-D levels below 30 ng/mL and PTH elevation based on stage of kidney disease, evidence that the suboptimal 25-OH-D level had physiologic consequences. Residents unable to transfer independently had 25-OH-D levels 1.6 ng/mL lower than those able to transfer independently. A regression analysis performed in residents unable to transfer independently (less likely to be exposed to the sun) demonstrated that the average increase in 25-OH-D level per 100 IU of D(3) in a 70-kg resident was 2.1 ng/mL versus 1.8 ng/mL for vitamin D(2). CONCLUSION: Nursing home residents should receive at least 800-1000 IU of D(3) per day in an effort to maintain optimal vitamin D levels.

Between-meal risedronate does not alter bone turnover in nursing home residents.

OBJECTIVES: To assess the effect of between-meal weekly risedronate and daily calcium 630 mg and vitamin D 400 IU on bone turnover markers. DESIGN: Randomized,double-blind,placebo-controlled trial. SETTING: Skilled nursing home (NH). PARTICIPANTS: Sixty skilled-NH residents (46 men, 14 women), mean age+/-standard deviation of 76+/-6, were randomized to receive risedronate 30 mg (n=31) or matching placebo (n=29) once weekly for 12 weeks. All received 315 mg calcium with 200 IU vitamin D twice daily. MEASUREMENTS: Bone-specific alkaline phosphatase (BSAP), N-telopeptide of type 1 collagen (NTx), 25-hydroxyvitamin D (25OHD), and parathyroid hormone were measured at baseline and 6 and 12 weeks. RESULTS: Risedronate reduced BSAP significantly more than placebo (P<.05) at 6 weeks but not at 12 weeks; no treatment effect on serum NTx was observed. Defining hypovitaminosis D as a serum 25OHD concentration below 32 ng/mL, 50 of 53 (94%) study participants were low at baseline (mean 25OHD 19 ng/mL). Vitamin D levels remained insufficient in 74% of participants after 12 weeks. CONCLUSION: In this NH population, weekly risedronate administered using a between-meal dosing schedule reduced serum BSAP at 6 weeks of treatment; this effect was not observed at 12 weeks. The overall lack of change in bone turnover markers suggests that this risedronate dose and schedule would not be expected to increase bone density or reduce fracture risk in this population. Hypovitaminosis D was common and not reliably corrected by 400 IU of vitamin D daily. Despite an extremely high osteoporotic fracture risk in NH residents, additional study is required to determine under which conditions pharmacological treatment is efficacious in this population and define approaches that assure vitamin D repletion.