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).