Hypovitaminosis D
| Vitamin D deficiency | |
|---|---|
 |
|
| Calcitriol (1,25-dihydroxycholecalciferol). Active form. Note extra OH groups at upper right and lower right. | |
| Classification and external resources | |
| Specialty | endocrinology |
| ICD-10 | E55 |
| ICD-9-CM | 268 |
| DiseasesDB | 13942 |
| MeSH | D014808 |
Vitamin D deficiency, or hypovitaminosis D, can result from inadequate nutritional intake of vitamin D, 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.
Vitamin D deficiency is typically diagnosed by measuring the concentration of the prehormone calcidiol (25-hydroxyvitamin D) in the blood. which is a precursor to the active form 1,25-dihydroxyvitamin D (calcitriol). One 2008 review has proposed the following categories for hypovitaminosis D:
These ranges are based on a Canadian range. Season, race and dietary intake affect 25-HydroxyVitamin D levels. Highest levels are found in the summer months and lowest levels during the winter. Other authors have also 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.
Note that 1.0 nmol/L = 0.4 ng/mL for this compound.
Vitamin D deficiency is known to cause several problems, including:
The role of diet in the development of rickets was determined by Edward Mellanby between 1918 and 1920. In 1921, Elmer McCollum identified an antirachitic substance found in certain fats that could prevent rickets. Because the newly discovered substance was the fourth vitamin identified, it was called vitamin D. The 1928 Nobel Prize in Chemistry was awarded to Adolf Windaus, who discovered the steroid 7-dehydrocholesterol, the precursor of vitamin D.
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