Vitamins are essential nutrients that are required for healthy living. Vitamin D is a fat-soluble vitamin that is important for calcium and phosphorus metabolism. It works together with Parathormone, or PTH, released by the parathyroid gland. Ultraviolet light converts fats present in human skin into vitamin D3, or cholecalciferol. This vitamin D3 undergoes activation in the liver and kidneys. Vitamin D deficiency causes bone disorders.
Causes of Vitamin D Deficiency
Vitamin D is found in blood in both active and inactive forms. Vitamin D deficiency may develop secondary to decreased sun exposure. Since vitamin D3 is formed in the skin and then undergoes activation in the liver and kidney, liver and kidney diseases can affect vitamin D levels in the blood. Measurement of 25(OH)D3, or 25 hydroxycholecalciferol in the blood is used as a measure to diagnose vitamin D deficiency and toxicity. Normal blood level is 10 to 50 ng/mL. Vitamin D deficiency means the blood level is below the normal range.
Supplementation for Vitamin D Deficiency
Daily oral supplementation of vitamin D up to 400 IU, or international units, is enough to prevent deficiency. Multivitamin capsules contain enough vitamin D to meet daily requirements. Meals containing vitamin D-fortified food such as milk, butter and cheese can also be a good source.
Vitamin D Dosage for Deficiency
Severe deficiency of vitamin D leads to conditions termed rickets in children and osteomalacia in adults. These conditions occur after prolonged or chronic vitamin D deficiency. They can be treated with vitamin D high-dosage injections or capsules of 50,000 IU per week for three to 12 weeks, followed by oral maintenance therapy of 800 IU daily.
Deficiency Symptoms
Calcium and phosphate salts provide strength and hard structure to bone. Vitamin D deficiency causes bones disorders due to decreased calcium and phosphorus deposits in bones. In children, rickets is characterized by weakness and bowing of weight-bearing bones. Osteomalacia in adults leads to bone pain and increased risk of fractures.
Sun Exposure and Food Products
Fortification of food products like milk, butter, cheese and cooking oil with vitamin D has helped decrease the incidence of vitamin D deficiency. Sunlight is necessary for children to make vitamin D in their skin. Though not a common cause of vitamin D deficiency in developed countries, parents tend to keep children inside for weeks and months during cold weather, leading to Vitamin D deficiency. Medical data is sparse about the time and intensity of sun exposure that could be enough for vitamin D production in the skin, but performing usual activities outside is considered enough.
References
- "Pocket Guide to Diagnostic Tests, 5e"; Diana Nicoll, Stephen J. McPhee, Michael Pignone, Chuanyi Mark Lu; 2010
- "Harrison's Principles of Internal Medicine, 17e"; Anthony S. Fauci, Eugene Braunwald, Dennis L. Kasper, Stephen L. Hauser, Dan L. Longo, J. Larry Jameson, and Joseph Loscalzo; 2008
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