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Vitamin D insufficiency and deficiency in children and adolescents

Madhusmita Misra, MD, MPH
Section Editors
Kathleen J Motil, MD, PhD
Marc K Drezner, MD
Deputy Editor
Alison G Hoppin, MD


Vitamin D is an essential nutrient that plays an important role in calcium homeostasis and bone health. Severe deficiency of vitamin D causes rickets and/or hypocalcemia in infants and children and osteomalacia in adults or adolescents after epiphysial closure; severe vitamin D deficiency may also be associated with hypocalcemia, which may cause tetany or seizures. These disorders occur with the highest frequency among children in malnourished populations and in children with chronic illnesses. Rickets also occurs in children in developed nations if sufficient vitamin D intake is not ensured through the use of supplements and fortified foods, particularly if exposure to sunlight is limited. The clinical evaluation and treatment of a child with rickets is discussed separately. (See "Overview of rickets in children" and "Etiology and treatment of calcipenic rickets in children", section on 'Nutritional rickets'.)

The clinical consequences of mild vitamin D deficiency are less well established. However, chronically low vitamin D levels are associated with the development of low bone mineral density and other measures of reduced bone health, even in the absence of rickets. The definition, causes, and prevention of vitamin D deficiency in children, and the treatment of vitamin D deficiency in the absence of rickets will be reviewed here.

The causes and treatment of vitamin D deficiency in adults are discussed in separate topic reviews. (See "Causes of vitamin D deficiency and resistance" and "Vitamin D deficiency in adults: Definition, clinical manifestations, and treatment".)


Vitamin D is a prohormone that is synthesized in the skin after exposure to ultraviolet radiation, or absorbed from food sources. Less than 10 percent of vitamin D comes from dietary sources in the absence of food fortification or use of supplements. The prohormone is then converted to the metabolically active form in the liver and kidneys (figure 1). (See "Overview of vitamin D", section on 'Metabolism'.)

Cholecalciferol, or vitamin D3, is the form of vitamin D found in animal products and some vitamin D supplements. It is formed when ultraviolet-B (UV-B) radiation (wavelength 290 to 315 nm) converts 7-dehydrocholesterol in epidermal keratinocytes and dermal fibroblasts to pre-vitamin D, which subsequently isomerizes to vitamin D3.


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