|
Hypovitaminosis D is a deficiency of vitamin D. It can result from inadequate nutritional intake of vitamin D and/or inadequate sunlight exposure (in particular sunlight with adequate ultraviolet B rays), disorders limiting vitamin D absorption, and conditions impairing vitamin D conversion into active metabolites—including certain liver, kidney, and hereditary disorders. Deficiency impairs bone mineralization, leading to bone softening diseases as rickets in children and osteomalacia and osteoporosis in adults.〔 Emerging evidence suggests vitamin D plays a role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). ==Classifications== Hypovitaminosis D is typically diagnosed by measuring the concentration in blood of the compound 25-hydroxyvitamin D (calcidiol), which is a precursor to the active form 1,25-dihydroxyvitamin D (calcitriol). One 2008 review has proposed the following four categories for hypovitaminosis D: * Insufficient 50-100 nmol/L (20-40 ng/mL) * Mild 25–50 nmol/L (10–20 ng/mL) * Moderate 12.5–25.0 nmol/L (5-10 ng/mL) * Severe < 12.5 nmol/L (< 5 ng/mL) Note that 1.0 nmol/L = 0.4 ng/mL for this compound.〔 Other authors have suggested that a 25-hydroxyvitamin D level of 75–80 nmol/L (30–32 ng/mL) may be sufficient〔〔 although a majority of healthy young people with comparatively extreme sun exposure did not reach this level in a study done in Hawaii. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hypovitaminosis D」の詳細全文を読む スポンサード リンク
|