Premium
Response of Vitamin D Concentration to Vitamin D 3 Administration in Older Adults without Sun Exposure: A Randomized Double‐Blind Trial
Author(s) -
Schwartz Janice B.,
Kane Lynn,
Bikle Daniel
Publication year - 2016
Publication title -
journal of the american geriatrics society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.992
H-Index - 232
eISSN - 1532-5415
pISSN - 0002-8614
DOI - 10.1111/jgs.13774
Subject(s) - medicine , vitamin d and neurology , calcifediol , parathyroid hormone , vitamin , endocrinology , randomized controlled trial , vitamin d deficiency , calcitriol , renal function , calcium
Objectives To determine the dose‐response relationship between 25‐hydroxyvitamin D (25( OH )D) and supplemental vitamin D 3 in elderly nursing home residents. Design Randomized double‐blind investigation. Setting Nursing home. Participants Of 81 women (n = 51) and men (n = 30) (mean age 87.4 ± 8) enrolled, 72 completed the study. Intervention Sixteen weeks of oral vitamin D 3 at 800, 2,000, or 4,000 IU /d or 50,000 IU /wk. Measurements The main outcome was 25( OH )D concentrations (tandem mass spectrometry) after 16 weeks. Free 25( OH )D and intact parathyroid hormone ( iPTH ) were also analyzed. Safety monitoring of calcium and estimated glomerular filtration rate was performed, and adherence and clinical status were measured. Results 25( OH )D concentrations increased with dose ( P < .001) and were higher with 50,000 IU /wk ( P < .001) than other doses and with 4,000 IU /d than 800 or 2,000 IU /d, but 800 IU and 2,000 IU /d did not differ. One subject receiving 800 IU /d had concentrations less than 20 ng/ mL . All subjects receiving more than 2000 IU /d had concentrations of 20 ng/ mL and greater. Free 25( OH )D concentrations rose with total 25(OH) vitamin D. Total and free 25( OH )D were related to calcium concentrations; only free 25( OH )D was related to iPTH . Conclusion 25( OH )D increased linearly with 800 to 4,000 IU /d and 50,000 IU /wk of vitamin D 3 , without a ceiling effect. Data suggest that some elderly adults will require more than 800 IU /d of vitamin D 3 to ensure adequate vitamin D levels. Changes in 25( OH )D with vitamin D 3 were related to starting concentrations (greatest with the lowest concentrations and unchanged with 800 and 2,000 IU /d if 20–40 ng/ mL ). Relationships between serum calcium and iPTH and free 25( OH )D suggest the potential for free 25( OH )D in defining optimal 25( OH )D concentrations.