Vitamin D Deficiency

Vitamin D deficiency in infants causes development of rickets in them. Such children exhibit peculiar characteristics of delayed walking, and prefer prolonged periods of sitting. In older children, walking becomes painful and in severe cases, bow legs may develop. In adolescent girls, the pelvic bones flatten, which in turn causes narrowing of the birth canal. Vitamin D deficiency is the major and common cause of nutritional rickets.

In adults, vitamin D deficiency may precipitate as osteomalacia. Affected adults complain of muscle aches and pain. Such individuals are also prone to frequent fractures due to poorly mineralized skeletal matrix [7].

Serum levels of 25(OH) D less than 15 or 20 ng/mL are defined as vitamin D deficiency. Whereas, levels below 30mg/mL are considered to be insufficient levels of vitamin D. When the serum level of 25(OH) D is above 30ng/mL, then maximum intestinal absorption of calcium occurs. On the other hand, when the levels begin to fall below 30ng/mL, then the levels of parathyroid hormone get elevated. This is considered to be another important marker for vitamin D deficiency [8]. It indicates an inverse relationship between parathyroid hormone and 25(OH) D. Measuring the serum 25(OH) D levels is the best method to determine vitamin D deficiency.

Vitamin D deficiency is treated through administration of its supplements. The dosage schedule depends on the age of the individual, and extent of deficiency that has set in. A daily maintenance dose of vitamin D for children and adults is given to be about 600 – 2000 IU daily. For the deficient population, doses higher than the recommended limits are suggested to be taken on weekly basis with additional extra allowance to meet daily requirements.

It is necessary that the 25(OH) D levels are checked post supplementation program. This is required to know whether the levels have reached the normal levels or not. If the levels continue to remain low, then the method of UVB light therapy is used for improving the vitamin D status [9].

Timely initiation of treatment is necessary to prevent occurrence of hip and nonvertebral fractures. Individuals should be put on supplements of vitamin D, when the first signs of deficiency are noticed. Prolonged deficiency of vitamin D can cause onset of severe and debilitating conditions, such as fractures, rickets and osteoporosis. Several studies have also demonstrated a relation between low levels of circulating vitamin D, and increase risk of developing, diabetes mellitus, cardiovascular disease and cancer [6].

Vitamin D deficiency can occur due to the following factors:

• Lack of exposure to sunlight: Vitamin D is synthesized in the skin when exposed to sunlight. Individuals who stay indoors, or children who do not indulge in outdoor games, may develop vitamin D deficiency [2].
• Malabsorption: Individuals with malabsorption syndromes, such as celiac disease, cystic fibrosis, and short bowel syndrome, or those who have undergone resection of small intestine also develop vitamin D deficiency.
• Insufficient amounts of vitamin D in breast milk: Human breast milk does not contain adequate amounts of vitamin D. Therefore, infants who are exclusively breast fed are at risk of developing deficiency of vitamin D.
• Medications and drugs: Certain types of medications such as rifampin, dilantin and phenobarbital, are known to interfere with absorption of vitamin D causing its deficiency.

Vitamin D deficiency is a common phenomenon for the elderly population and those who are hospitalized. It has been estimated that in the US, about 60% of nursing residents and 57% of patients who were hospitalized developed vitamin D deficiency [3].

Seasonal variations also have an impact on the vitamin D status of individuals. A study carried out on healthy individuals of Boston revealed that, at the end of winter season, the individuals under study had insufficient levels of vitamin D [4].

Vitamin D primarily exists in 2 different forms, D2 known as ergocalciferol and D3 known as cholecalciferol. The D3 form is synthesized when the body is exposed to sunlight. Some dietary sources such as fish oils and salted fish also contain vitamin D3. Vitamin D is important for optimal functioning of various body organs. However, its most vital functioning is to promote the absorption of calcium and phosphate from the intestine, thereby maintaining optimal bone health. Therefore, deficiency of vitamin D causes poor bone health predisposing individuals to develop several bone disorders [5].

In order to avoid vitamin D deficiency from setting in, it is required that individuals get adequate exposure to sun. Children should be encouraged to indulge more in outdoor games. Infants who are exclusively breastfed should be started on vitamin D supplements after 2 months; this is so because breast milk does not contain adequate amounts of vitamin D. In addition, pregnant women should also be given vitamin D supplements, to prevent onset of its deficiency in the woman and the fetus. Elderly population who do not get enough sun exposure should also take daily of 10 micrograms of vitamin D [10].

Vitamin D deficiency is characterized by insufficient levels of vitamin D in body that can cause several debilitating conditions. Lack of intake, exposure to sunlight and, or, malabsorption can cause deficiency of vitamin D to set in. Vitamin D is vital for calcium and phosphorus homeostasis, as well as is important for maintaining skeletal health. Most often signs of mild vitamin D deficiency do not show up easily. However, in cases of severe deficiency, affected individuals often end up contracting bone diseases such as rickets and osteomalacia [1].

Definition

Vitamin D deficiency occurs due to lack of intake, sun exposure, or certain malabsorption syndrome. Infants who are only breast fed are also susceptible to develop deficiency of vitamin D.

Cause

Individuals who stay indoors, such as hospitalized patients, or nursing residents, do not get sufficient sun exposure. Lack of sun exposure can cause vitamin D deficiency to set in. In addition, malabsorption syndromes, such as celiac disease, cystic fibrosis and short bowel syndrome, can also increase the risk of developing vitamin D deficiency.

Symptoms

Symptoms of vitamin D deficiency in infants include delayed crawling and walking. Affected children prefer to sit rather than walk, and in severe cases can develop rickets. In adults, vitamin D deficiency manifests as development of osteomalacia.

Diagnosis

Serum level of 25(OH) D is assessed to diagnose vitamin D deficiency. Levels low than 15 or 20ng/mL confirms vitamin D deficiency.

Treatment

Treatment involves giving vitamin D supplements to the affected individuals. In case, when supplements do not work, then UVB light therapy can be considered.

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10. Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, Treatment, and Prevention of Vitamin D Deficiency: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. Jun 6 2011