What Is Abnormally Low Vitamin D?

You obtain vitamin D, also known as the sunshine vitamin, from your diet and through skin production in association with sun exposure. An abnormally low vitamin D level indicates a deficiency of this essential substance in your body, which can lead to serious medical problems. Options to correct a vitamin D deficiency include increased dietary intake, increased sun exposure and nutritional supplementation.

Normal Level

Your doctor determines whether you have an abnormally low vitamin D level by having your blood tested. The normal range for vitamin D is approximately 30 to 74 nanograms per mL of blood; the range may vary slightly from one laboratory to another. If you have less than 30 nanograms of vitamin D per mL of blood, you probably have a deficiency.

Symptoms

Because vitamin D is essential for muscle and bone health, symptoms of a deficiency manifest in your musculoskeletal system. Defective bone formation from a vitamin D deficiency may cause bone pain. You may also experience muscular pain and weakness with a vitamin D deficiency. Symptoms of a vitamin D deficiency are commonly overlooked because they are subtle and can be caused by a number of medical conditions. If you experience any of these symptoms, talk with your doctor. Treatment of a vitamin D deficiency in adults typically leads to alleviation of musculoskeletal symptoms within a short period.

Lifestyle Causes

Vitamin D deficiency can develop for a variety of reasons. Inadequate sun exposure is a common contributing factor. Larry Johnson, M.D., notes in "The Merck Manual for Healthcare Professionals" that direct sun exposure for 5 to 15 minutes three times a week is recommended to prevent a vitamin D deficiency.
Insufficient vitamin D from your diet is another common contributing factor to the development of a deficiency. Fortified milk and fruit juice, egg yolks, salmon, herring, mackerel and cod liver oil are good sources of dietary vitamin D. Michael Holick, M.D., and Tai Chen, Ph.D., note in an April 2008 article published in the "American Journal of Clinical Nutrition" that wild salmon contains a higher concentration of vitamin D than farmed salmon.

Medical Causes

Intestinal problems that interfere with your ability to absorb dietary fats may lead to a vitamin D deficiency. Examples include chronic pancreatitis, celiac disease, cystic fibrosis and Crohn's disease. Kidney and liver failure also commonly lead to a vitamin D deficiency. Certain medications may contribute to the development of a vitamin D deficiency, including antiepileptics, prednisone, orlistat and cholestyramine. St. John's wort may also provoke a vitamin D deficiency. Talk with your doctor if you have concerns about the potential interaction between your medications or supplements and vitamin D.