Longitudinal Evaluation of Vitamin D Status in Healthy Subjects from Southern Italy: Seasonal and Gender Differences |
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Authors: | V Carnevale S Modoni M Pileri A Di Giorgio I Chiodini S Minisola R Vieth A Scillitani |
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Institution: | (1) Ospedale ‘Casa Sollievo della Sofferenza’, IRCCS, San Giovanni Rotondo (FG), Italy, IT;(2) Unit of Endocrinology, San Giuseppe-Fatebenefratelli Hospital, Milan, Italy, IT;(3) Department of Clinical Sciences, Universita`‘La Sapienza’, Rome, Italy;, IT;(4) Department of Laboratory Medicine and Pathobiology, Mount Sinai Hospital, Toronto, Canada, CA |
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Abstract: | Vitamin D status is currently considered among the relevant determinants of skeletal integrity. Since vitamin D levels present
seasonal variations, we longitudinally studied young healthy men and women in order to investigate the related physiologic
modifications of both calcium homeostasis and bone remodeling. Thirty-two men (mean age 39.4 ± 7.8 years) and 58 premenopausal
women (aged 36.9 ± 6.4 years) from southern Italy were studied. In all subjects the following parameters were measured both
in winter and in summer: serum calcium, phosphorus, creatinine, total alkaline phosphatase activity, 25-hydroxyvitamin D (25OHD),
parathyroid hormone (PTH), osteocalcin (BGP), together with urinary calcium (Ca/Cr), total pyridinoline (Pyr/Cr) and deoxypyridinoline
(d-Pyr/Cr), corrected for creatinine excretion. In both sexes 25OHD levels were significantly higher in summer, while PTH
values were lower, than in winter. The prevalence of hypovitaminosis D, defined by concentrations of 25OHD lower than 30 nmol/l,
was 17.8% in winter and 2.2% in summer in the whole sample, while it was 27.8% and 3.4%, respectively, among female subjects.
Indeed male subjects did not display hypovitaminosis D, having throughout the year significantly higher calcium and 25OHD
levels together with lower PTH values, than the women. Moreover, alkaline phosphatase total activity was more elevated in
men both in winter and in summer. In women, during winter, bone remodeling markers levels were higher while urinary calcium
levels were lower than in summer. In the whole sample serum 25OHD correlated positively with serum calcium and inversely with
PTH. The seasonal percentage variations in PTH were inversely correlated with those of Ca/Cr. Our results show a relatively
high prevalence of subclinical vitamin D deficiency among young healthy women from southern Italy. Significant gender-specific
differences have been demonstrated in both calcium homeostasis and skeletal remodeling indexes; the seasonal fluctuations
in the vitamin D–PTH axis are accompanied by cyclical variations of bone turnover rate, which were more pronounced in women.
Received: 11 January 2001 / Accepted: 6 July 2001 |
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Keywords: | :Calcium homeostasis – Gender differences – 25-Hydroxyvitamin D – Markers of bone turnover – PTH |
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