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Age‐, gender‐, and weight‐related effects on levels of 25‐hydroxyvitamin D are not mediated by vitamin D binding protein
Author(s) -
Bolland Mark J.,
Grey Andrew B.,
Ames Ruth W.,
Horne Anne M.,
Mason Barbara H.,
Wattie Diana J.,
Gamble Greg D.,
Bouillon Roger,
Reid Ian R.
Publication year - 2007
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.2007.02873.x
Subject(s) - medicine , endocrinology , vitamin d and neurology , body mass index , body weight
Summary Objective 25‐hydroxyvitamin D (25OHD) levels are inversely related to body weight, and have been reported to decline with age and be lower in women than men. We hypothesized that these findings might be explained by effects of these variables on vitamin D binding protein (DBP) levels. We set out to determine the relationships between DBP and gender, 25OHD, body weight and body composition. Design Cross‐sectional analysis. Patients One hundred healthy, middle‐aged and older, community‐dwelling men and women. Measurements All participants were measured for 25OHD, DBP, body weight, bone mineral density and body composition. Results Women had higher mean DBP levels than men but lower total 25OHD levels [DBP: women, mean (SD) 339 (36) mg/l, men 307 (71) mg/l, P = 0·005; 25OHD: women 67 (23) nmol/l, men 91 (39) nmol/l, P < 0·001]. In women, there were significant positive relationships between DBP and albumin ( r = 0·33) and 25OHD ( r = 0·34) whereas in men there were no significant relationships between DBP and any measured variables. There was no significant relationship between DBP and age, body weight, body mass index, fat mass or percentage fat in men or women. Conclusion We found no evidence to support the hypothesis that DBP levels are related to age, or adiposity. The changes in 25OHD levels with age, gender, or fat mass are not due to underlying relationships between DBP and these variables. This suggests that the relationships consistently observed between 25OHD and body composition and gender are of biological origin and not due to adaptation to changes in transport proteins.