Vitamin D functions to regulate calcium and phosphorus in your blood. Blood calcium is vital to your bones and your nervous system. If there is not enough vitamin D to assist your body in absorbing dietary calcium, blood calcium levels drop and result in a calcium deficiency called hypocalcemia. Hypocalcemia causes softened bones in children, osteomalacia in adults and painful, weak muscles in both.
Vitamin D
Active vitamin D is synthesized in your skin from exposure to UV light, or you can obtain it by dietary supplementation. One of the few foods with natural vitamin D is oily fish, while milk, orange juice and cereals are commonly fortified with this vitamin. Vitamin D is metabolized by your liver into biologically active 25-hydroxyvitamin D, which is needed for dietary calcium absorption and regulation of bone calcium. Insufficient vitamin D promotes hypocalcemia and causes a variety of symptoms.
Parathyroid Gland
Two small parathyroid glands lay next to the thyroid glands in your neck and function as sensors of blood calcium. These glands release parathyroid hormone, which stimulates the formation of biologically active vitamin D within your body. Then, the vitamin D stimulates the absorption of dietary calcium and mobilizes calcium from within your tissues. Any disruption in the pathway of calcium absorption or mobilization will cause hypocalcemia.
Hypocalcemia
Hypocalcemia can be asymptomatic or life-threatening, depending on the cause and duration. Severe vitamin D deficiency, which causes low calcium levels, results in the deformed bones of rickets and the brittle bones of osteoporosis. Other clinical hypocalcemia signs include neurological symptoms, muscular symptoms and skin conditions. Hypocalcemia is diagnosed when your blood serum calcium levels become lower than 8.2 mg/dL. Low serum phosphate levels can determine if the calcium deficiency is related to the parathyroid hormone.
Considerations
Vitamin D deficiency is a reemerging skeletal health problem. Dietary changes and lack of outdoor exposure have increased the risk of the deficiency in Westernized nations. A report in a 2006 issue "Pediatrics" journal examines the case of a 17-year-old boy who experienced seizures and fractured hips due to hypocalcemia. Also, a review of studies published in May 2008 in "Heart" discusses how hypocalcemia and vitamin D deficiency are preventable causes of heart failure in infants.
Treatment and Prevention of Hypocalcemia
Most cases of hypocalcemia can be prevented by adequate dietary vitamin D, whether through food or supplements. In an acute situation, such as seizures or muscle spasms, intravenous calcium is administered. Sometimes, hypocalcemia is related to medications that bind calcium, pancreatitis or even hereditary disorders and not dietary vitamin D. Once a diagnosis of hypocalcemia is confirmed, a doctor should carefully investigate the cause.
References
- MayoClinic.com; Vitamin D; April 2011
- Linus Pauling Institute; Vitamin D; Jane Higdon; March 2004
- Colorado State University; Endocrine Control of Calcium and Phosphate Homeostasis; R. Bowen; October 2003
- Cleveland Clinic; Hypocalcemia; Mario Skugor
- "Pediatrics;" Hypocalcemic Seizures and Secondary Biolateral Femoral Fractures...; David Schnadower, et al.; 2006
- "Heart;" Hypocalcaemia and Vitamin D Deficiency--An Important, But Preventable, Cause of Life-Threatening Infant Heart Failure; S. Maiya, et al.; May 2008
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