Vitamin D helps in the calcification of bone. It is made by the action of sunlight in the skin; sunlight exposure and adequate dietary intake of vitamin D are needed to sustain adequate levels of active vitamin D in the blood. Vitamin D deficiency can occur in both children and adults. In the metabolism of vitamin D, the liver's role is to convert vitamin D to hydroxyvitamin D. When the liver is impaired by disease, vitamin D metabolism is affected as well.
Causes
Hepatitis and cirrhosis of the liver have been associated with abnormal levels of vitamin D. Poor intake of vitamin D in the diet, in combination with inadequate sunlight exposure to the skin, leads to low vitamin D in the blood. Crohn's disease and irritable bowel syndrome, which are diseases that affect the intestines, have been associated with vitamin D deficiency.
Complications
Hypocalcemia, or low calcium in the blood, is a serious problem that results from vitamin D deficiency; it causes irregularity of heartbeat and seizures. The brain and heart are organs that function well when calcium levels are normal in the blood. Hypophosphatemia, or low blood phosphate, is a result of too much parathyroid hormone release from the parathyroid gland. Bone softening is another complication that can occur in adults as osteomalacia and in children as rickets.
Symptoms
In vitamin D deficiency, symptoms such as proximal muscle weakness often occur. Tetany, a condition of uncontrollable muscle contractions, occurs as well, but as a consequence of hypocalcemia, or low blood calcium. Tetany causes peculiar sensations over the tongue, lips and fingers. Newborns can also have tetany if the mother were deficient in vitamin D during pregnancy. Seizures are noted to occur in severe hypocalcemia.
Diagnosis
Diagnosis of vitamin D deficiency begins with the drawing of a blood sample from a vein in the arm using a 21-gauge needle. The process is associated with minimal pain if done correctly. The blood is then tested for levels of active vitamin D, or 25OHD. If 25OHD is greater than 30 ng/mL in the blood then it is normal; if it's less than 20 ng/mL, then it is deficient.
Treatment
Treatment is centered on supplementation of vitamin D3, but supplementation is a temporary measure when vitamin D deficiency is caused by a diseased organ, such as in cirrhosis or in hepatitis. Liver disease ultimately has to be placed under control for vitamin D deficiency to be cured. The U.S. Department of Health and Human Services confirms that the use of 700 to 800 international units, or IUs, of vitamin D3 per day and 500 to 1,200 mg of calcium are very effective in boosting 25OHD in the blood and reducing the likelihood of fractures.
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