- The most common nutritional deficiency worldwide, characterised by serum 25-hydroxyvitamin D <50 nanomol/L (<20 nanograms/mL). Vitamin D insufficiency is regarded as a serum 25-hydroxyvitamin D level between 51 and 72 nanomol/L (21 and 29 nanograms/mL).
- Main causes include sun avoidance, using sun protection, increased skin pigmentation, inadequate dietary and supplemental vitamin D intake, malabsorption syndromes, obesity, and medication use.
- Acquired and inherited disorders that either reduce or prevent the metabolism of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D also present with biochemical and skeletal abnormalities seen with vitamin D deficiency, but in a more severe form.
- Most patients are asymptomatic. Severe, prolonged vitamin D deficiency causes growth retardation and rickets in children and osteomalacia, osteopenia, and osteoporosis in adults.
- Both vitamin D deficiency and vitamin D insufficiency are corrected by giving vitamin D2 or vitamin D3 in treatment doses followed by lifelong maintenance doses; adequate, sensible sunlight exposure should be encouraged.
- Additional replacement with 1,25-dihydroxyvitamin D or one of its active analogues is necessary for those with disorders of vitamin D metabolism.
Last updated: Dec 19, 2012