Vitamin D plays a supportive role in the development and calcification of bones. Vitamin D has effects all over the body. It is synthesized in the skin by the aid of sunlight. Vitamin D maintains the level of calcium in the blood by stimulating its absorption in the intestines. When vitamin D is deficient, it also leads to hypocalcemia, or low blood calcium. The parathyroid glands secrete parathyroid hormone in response to low blood calcium.
Causes of Vitamin D Deficiency
Common liver diseases, including liver cirrhosis and hepatitis have been associated with vitamin D deficiency, as the liver is integral to vitamin D metabolism. Lack of sun exposure, such as in cold climates and in winter months, can lead to vitamin D deficiency. Lack of sun exposure plus insufficient vitamin D in the diet leads to a more pronounced deficiency in vitamin D in the blood. Intestinal diseases are also known to cause vitamin D deficiency, such as irritable bowel disease and Crohn's disease, according to Sciencedaily.com.
Complications of Vitamin D Deficiency
Calcium cannot be absorbed in the intestines without the help of vitamin D. Lack of vitamin D leads to hypocalcemia, a low blood concentration of calcium. Serious risks are associated with hypocalcemia, which are irregular beating of the heart and seizures. Hypocalcemia stimulates the parathyroid gland to increase its production of parathyroid hormone; the action of the parathyroid hormone is to cause an increase of calcium in the blood by stimulating cells that break down bone to release calcium. Bone softening is also a consequence of vitamin D deficiency, according to the Merck Manuals.
Symptoms
Weakness of the muscles and muscle aches are experienced in vitamin D deficiency. Tetany results from the hypocalcemia associated with vitamin D deficiency. Tetany causes abnormal sensations over the lips, the tongue and the fingers, the Merck Manuals report. Uncontrollable twitching, or facial spasms, can occur in vitamin D deficiency. In newborns, tetany can be seen if the mother had vitamin D deficiency during pregnancy.
Testing
Vitamin D deficiency can be evaluated by extraction of a blood sample from a vein in the arm. 25OHD is the active form of vitamin D in the blood. A 25OHD concentration greater than 30 ng/mL, short for nanograms per milliliter, is normal, whereas with a concentration less than 20 ng/mL, vitamin D is considered deficient.
Management
The U.S. Department of Health & Human Services advises the use of 700 to 800 international units of vitamin D3 per day with 500 to 1,200 milligrams of calcium per day; this dose combination has resulted in reduced bone fractures and due to effective increase in 25OHD in the blood. Sun exposure is recommended also, as it will have added benefits to vitamin D concentration in the blood.
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