Abstract
ObjectivesVitamin D deficiency, which is common worldwide, increases the risks of falls and fractures and can lead to increased morbidity and mortality. However, the clinical utility and relevance of vitamin D activation remain unknown. The aim of the present study was to clarify the clinical usefulness of serum 1,25-dihydroxyvitamin D (1,25D)/25-hydroxyvitamin D (25D) ratio for assessment of the extent of bone metabolism.MethodsWe retrospectively screened data for 87 patients whose serum 1,25D and 25D levels were measured. Eight patients who were taking vitamin D preparations were excluded, and data for 79 patients (33 males and 46 females) were analyzed. Since menopausal status can be associated with serum vitamin D level, we divided the patients by gender and divided the female patients into two groups at the age of 50 years.ResultsThe median serum 1,25D/25D ratio was significantly lower in males than in females, with the most considerable difference in all males [4.1 (interquartile range: 2.3-5.8) × 10−3] versus elderly females (aged ≧50 years) [7.9 (3.3-10.1) × 10−3). Main disorders were endocrine (30.6%), inflammatory (18.5%), and bone-related (16.7%) disorders. The ratios of serum 1,25D/25D had significant negative correlations with femoral dual-energy X-ray absorptiometry % young adult mean (DEXA %YAM) (R=−0.35) and lumbar DEXA %YAM (R=−0.32). Significant correlations were found between the 1,25D/25D ratio and serum levels of inorganic phosphate (iP), parathyroid hormone, and alkaline phosphatase (ALP). The 1,25D/25D ratio had gender-specific characteristics: the ratio was significantly correlated with age in males (R=−0.49), while it was significantly correlated with BMI in females (R=0.34).ConclusionsThe results of this study suggested that vitamin D activity is negatively correlated with bone mineral density, being reduced in aged males but enhanced in obese females.
Highlights
Vitamin D is obtained in the body by food intake or by production from 7-dehydrocholesterol by exposure of the skin to ultraviolet B radiation [1]
Significant correlations were found between the 1,25-hydroxyvitamin D (25D)/25D ratio and serum levels of inorganic phosphate, parathyroid hormone, and alkaline phosphatase (ALP)
The 1,25D/25D ratio had genderspecific characteristics: the ratio was significantly correlated with age in males (R=−0.49), while it was significantly correlated with body mass index (BMI) in females (R=0.34)
Summary
Vitamin D is obtained in the body by food intake or by production from 7-dehydrocholesterol by exposure of the skin to ultraviolet B radiation [1]. 25D is subsequently metabolized to the hormonally active form, 1,25-dihydroxyvitamin D (1,25D), via 1α-hydroxylase encoded by the CYP27B1 gene [1]. Renal CYP27B1 is regulated primarily by parathyroid hormone (PTH) and calcitonin in stimulatory manners and by fibroblast growth factor-23 (FGF-23) and 1,25D itself in inhibitory manners [1]. CYP27B1 exists in extra-renal sites such as macrophages, and its expression in extra-renal sites is associated with granuloma-forming disorders and is regulated mainly by type I and type II interferons (IFNs) [2]. 1,25D has a cellular effect through the vitamin D receptor (VDR) [3], which leads to calcium absorption in the gut, bone metabolism, and parathyroid function. A recent study showed that a low vitamin D status is common worldwide and is associated
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