Vitamin D is a fat soluble vitamin that is available in a variety of different forms. The two forms most important to the human body, D2 and D3, are either obtained from the diet or synthesized from the skin following exposure to sunlight. The primary role of vitamin D is to assist in the absorption of calcium to maintain appropriate levels in the bloodstream. Vitamin D deficiency can occur as a result of intestinal disease that impairs fat absorption, kidney failure or insufficient exposure to sunlight, leading to a variety of unwanted effects in the body.
Hypocalcemia
The primary role of vitamin D is to aid in the absorption of dietary calcium in the intestinal tract and ensure that there is sufficient calcium in the bloodstream for use by bones and tissues. As a result of vitamin D deficiency, calcium absorption is impaired, leading to abnormally low levels of calcium in the bloodstream, a condition known as hypocalcemia. During bone development, the absence of sufficient calcium causes a condition of soft bones known as rickets in children or osteomalacia in adults. Weakened bones can cause pain, altered posture and be susceptible to breaking. In addition, hypocalcemia can lead to other muscular disorders, including spontaneous muscle spasms and tetany.
Secondary Hyperparathyroidism
Low levels of calcium in the blood signal the parathyroid gland to secrete increasing amounts of parathyroid hormone. Since the body works to keep calcium levels stable in the bloodstream, parathyroid acts to increase the level of calcium. Unfortunately, since dietary calcium absorption has been impaired, parathyroid hormone stimulates the breakdown of bone to replace the calcium absent in the bloodstream. The loss of bone density, termed osteoporosis, is often a complication of hyperparathyroidism. Symptoms of hyperparathyroidism may present as weakness, fatigue, excessive urination, depression, nausea and loss of appetite.
Hypercalcemia
Although vitamin D deficiency initially causes hypocalcemia, the resulting compensatory effects of the parathyroid gland can cause calcium levels in the blood to elevate too high, also known as hypercalcemia. Hypercalcemia has been associated with increased blood pressure and heart disease. Symptoms of hypercalcemia may include fatigue, muscle weakness, constipation and excessive thirst. In addition, excess calcium can accumulate in the kidneys, forming painful kidney stones.
Other Symptoms of Vitamin D Deficiency
Research has shown that vitamin D may also play a role in regulating mood. Low vitamin D levels have been found to have a correlation with the development of depression. Evidence has suggested that vitamin D also plays a role in the regulation of blood pressure, with higher blood pressures seen in some patients with vitamin D deficiencies. In addition, vitamin D may also have protective effects against certain cancers and autoimmune disorders. The treatment of vitamin D deficiency usually includes the use of vitamin D supplements. Patients should contact a physician if they feel they are at risk of developing a vitamin D deficiency.
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