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Calcitriol does not eliminate age‐associated differences in Ca absorption in women
Author(s) -
Wood Richard J,
Martini Ligia A,
Angelo Giana,
Saltzman Edward,
Booth Sarah L
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a991-a
Subject(s) - calcitriol , absorption (acoustics) , calcium metabolism , medicine , endocrinology , calcium , materials science , composite material
We compared intestinal calcium absorption in young and older women before and following 1 week of 1, 25‐dihydroxyvitamin D (calcitriol) treatment. Thirty‐five women (n=21 postmenopausal and n=14 premenopausal) were confined to a metabolic unit and fed an identical standardized diet supplying 600 mg Ca/d for 2 weeks. At the end of the first week, following an overnight fast a 6‐hour oral strontium absorption test was administered to all subjects to assess intestinal Ca absorption. All of the young women and half of the older women received calcitriol (1 microgram/d) for the second week. The other half of the older subjects received no calcitriol. Ca absorption was then reassessed with the oral strontium absorption test. Baseline Ca absorption was 36% lower in old vs young subjects (Sr AUC = 4.8 ± 0.4 vs 7.4 ± 0.8 mg/dl/hr, mean ± SEM, p<0.001, t‐test). There was no significant difference in Ca absorption in untreated older women (n=10) between the first and second Ca absorption tests (4.6 ± 0.4 vs 5.2 ± 0.5). Calcitriol treatment for 1 week resulted in a significant increase in Ca absorption in both young and older women. However, Ca absorption remained significantly lower in older (n=11) vs younger women following calcitriol supplementation (9.2 ± 0.6 vs 12.2 ± 1.2). These observations support the hypothesis that older women have relatively impaired Ca absorption compared to younger women. Moreover, although Ca absorption in older women is responsive to calcitriol treatment, it remains low suggesting that some other unidentified factor limits the efficiency of Ca absorption in postmenopausal women. Supported by CSREES 99‐35200‐7583 and USDA Cooperative Agreement 58‐1950‐9‐001.