Vitamin D is an important vitamin in the control of calcium and phosphate levels in the body. The active form of vitamin D is necessary for the absorption of calcium and phosphate from the intestine and for their incorporation into bone. Vitamin D deficiency can cause rickets in infants and bone fragility in adults and the elderly.
The Facts
There are two forms of vitamin D. According to the Merck Manual, vitamin D2 is the form present in high-dose vitamin supplements. Vitamin D3 is formed in the skin as a result of exposure to sunlight. It is also found in vitamin D-fortified foods like milk. Apart from its role in bone formation, growth and repair, vitamin D is important for muscle strength and immune system function.
Causes
The most common cause of vitamin D deficiency is lack of adequate exposure to sunlight. This happens, for example, in people who do not spend enough time outdoors, like institutionalized people or the elderly in nursing homes. It can also happen in breastfed infants who do not get enough sunlight, as breast milk does not contain adequate concentrations of vitamin D.
Symptoms
People with vitamin D deficiency have low levels of calcium and phosphate, as vitamin D is necessary to absorb those elements from the gut. Low levels of vitamin D, calcium and phosphate cause muscle aches and spasms, bone pain, and weakness. Infants can develop rickets. The symptoms of rickets include impaired growth; skeletal deformities, like bow legs, odd-shaped skull, and bumps in the ribcage. Rickets can also cause kidney disorders.
Diagnosis
The physical exam of people with vitamin D deficiency includes bone tenderness or pain. Lab tests can detect low levels of calcium and phosphate, as well as measure the levels of vitamin D. X-rays can detect bone thinning, bone deformities or fractures, and changes in the growth plates of children with rickets.
Treatment
About 10 minutes of sunshine three times a week is enough for the body to maintain appropriate levels of vitamin D. This may not be enough to overcome vitamin D deficiency; oral supplementation is also necessary. Supplementation is also important for breastfed infants. Treatment of adults with vitamin D deficiency may take one to two months of oral supplements or injections.
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