Hormones are biochemical molecules that different parts of the body use to communicate with each other. Carried through the bloodstream, hormones may signal cells, tissues and organs to perform specific functions. Many external factors can influence the amounts and activity of a particular hormone. Hypocalcemia as a result of vitamin D deficiency can stimulate a significant increase in the production of parathyroid hormone. Unfortunately, excess parathyroid hormone can produce unwanted physiological effects.
Vitamin D Regulates Calcium
Although vitamin D can be synthesized by the skin following exposure to sunlight, it can also be obtained from the diet. Milk is a food product that is often fortified with vitamin D. The main role of vitamin D within the body is to promote the absorption of calcium from the digestive tract. This is the main reason calcium supplements are often formulated to contain vitamin D.
Causes of Vitamin D Deficiency
Since vitamin D is a fat-soluble vitamin, malabsorption disorders that interfere with fat absorption can lead to a vitamin D deficiency. However, the skin is able to synthesize vitamin D from ultraviolet light. The primary causes of vitamin D deficiency are insufficient exposure to sunlight and kidney disease. Vitamin D deficiency occurs in kidney disease because the kidneys are responsible for converting vitamin D3 into the active form that is used by the body.
Symptoms of Vitamin D Deficiency
The initial symptoms of vitamin D deficiency are attributed to low calcium levels as a result of impaired dietary absorption of calcium. The absence of sufficient calcium during bone development can result in soft bones in both children and adults. Soft bones are at higher risk for fractures and difficulty with posture. In addition, hypocalcemia can lead to muscular disorders, including tetany and muscle spasms.
Vitamin D and Parathyroid Hormone
Low calcium levels stimulate the parathyroid gland to increase the production of parathyroid hormone. As the body attempts to compensate for lower calcium levels in the bloodstream, parathyroid hormone stimulates the breakdown of bone to supply calcium that can be redeposited into the bloodstream. Unfortunately, this can lead to a loss of bone density and the development of osteoporosis. Additional symptoms of hyperparathyroidism can include weakness, fatigue, depression, excessive urination, nausea and loss of appetite.
Hyperparathyroidism and Hypercalcemia
As calcium is redeposited into the bloodstream following the breakdown of bone, calcium levels can become excessively high. Symptoms of hypercalcemia may include muscle weakness, fatigue, constipation and excessive thirst. A major complication of high calcium is calcification of soft tissues and organs. Patients should contact a physician with concerns regarding vitamin D deficiency or hyperparathyroidism.
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