New clinical practice guidelines from the Endocrine Society recommend against screening the general population for vitamin D deficiency but do urge Americans to use vitamin D supplements to maintain healthy levels. The guidelines were published in the July 1, 2011 edition of the Journal of Clinical Endocrinology and Metabolism.
To develop the guidelines, the Endocrine Society formed a task force and used a consensus process involving a systematic review of evidence as well as input from several committees and their general membership. The society, an international organization with members who are professionals from various health-related fields, is dedicated to the study of the body's glands and hormones and their related diseases.
Vitamin D is a hormone that is essential for the formation and maintenance of bone and bone health. Unlike other vitamins, the body can make vitamin D when the skin is exposed to sunlight at midday. Since few foods naturally contain significant amounts of vitamin D, this is the primary source of the vitamin for adults and children. With widespread use of sunscreens that block much of the sunlight from reaching the skin, many individuals can have insufficient levels of vitamin D, says the Endocrine Society.
Nevertheless, the society found no evidence in their recent review to support routine vitamin D testing on a population-wide basis. They did conclude, however, that screening is useful for certain groups and for people who have conditions that put them at a greater risk of deficiency. This finding is in agreement with a report released late last year by the Institute of Medicine. The two organizations concur that a vitamin D level less than 20 ng/mL is considered deficient and requires treatment with vitamin D.
Individuals who are likely deficient and should have their level checked include those who have:
- Bone disorders such as rickets, osteomalacia and osteoporosis
- Chronic kidney disease
- Liver failure
- Conditions that affect the intestines and absorption of nutrients from the diet (malabsorption syndromes) such as celiac disease, cystic fibrosis, inflammatory bowel disease and Crohn disease
- Conditions requiring the use of certain drugs such as antiseizure medications, corticosteroids, and AIDS medications
- Some lymphomas
Groups at increased risk of vitamin D deficiency include:
- Dark-skinned people such as African-Americans and Hispanics
- Pregnant and breastfeeding women
- Older adults with history of falls or fractures not caused by trauma
- Obese children and adults
Though the two organizations maintain that screening should be confined to those who are most likely deficient, the Endocrine Society suggests that many people in the U.S. have suboptimal levels of vitamin D and require some degree of supplementation. Children older than 12 months and adults need to consume at least 600 IU of vitamin D each day, they advise, with adults over 70 requiring more than 800 IU and some at-risk adults needing at least 1500 IU. On this point, the reports from the two groups differ, with the Institute of Medicine asserting that most Americans received adequate levels of vitamin D through fortified foods in the diet and don't need supplements. (Read the article Vitamin D and Calcium Levels Adequate for Most Americans, Report Says from January 2011).
Additionally, the Endocrine Society found enough evidence in its review to suggest that the vitamin D level in the blood should be at least 30 ng/mL and further maintains that toxicity from the vitamin is rare. Ideally, the level should be between 40-60 ng/mL for children and adults, they purport. On the other hand, the Institute of Medicine contends that a level above 20 ng/mL is sufficient for bone health and that a level greater than 50 ng/mL can cause harm.
With these two major organizations diverging on some key issues regarding vitamin D, what can Americans take away from the two reports? How could two expert organizations reach such different conclusions? The main reason lies in the approach each organization took to develop their guidelines. The Institute of Medicine, while considering thousands of studies, put the most weight on the strongest type of studies, those in which people are randomly assigned to one treatment or another. However, for "high" levels, they considered much weaker data, and acknowledged that even fairly high vitamin D intakes (10,000 IU/day) are not usually associated with toxicity. The Institute of Medicine also considered what intakes would be safe for the whole population, over very long periods of time.The Endocrine Society looked at much the same evidence, but more strongly considered vitamin D intakes that would be adequate for people recommended for testing, that is, people at risk. Looking at the same data on safety as the Institute of Medicine, it reached a different conclusion that such high intakes (up to 10,000 IU/day) are safe. Using that information, it looked at blood levels of vitamin D that would be achieved on such intakes in determining safe level.
Unless you fall into one of the at-risk categories, you probably don't need a vitamin D test. However, you should talk to your doctor about your specific situation to determine your nutritional needs. Your doctor can help establish if and how much you should use vitamin D supplementation. She may ask you several lifestyle questions regarding diet and your usual time spent outdoors. She will also consider where you live and will get a thorough medical history to help determine your individual requirements. This all can be done as part of a routine check up.
If you are one of those who are at a greater risk of deficiency, consult your doctor about getting tested so you can learn your level and, if necessary, get proper treatment.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Holick MF et al. Evaluation, treatment, and prevention of vitamin D deficiency: An Endocrine Society clinical practice guideline. J Clin Endocrinol Metab, 96(7): 1911 (July 1, 2011). Available online at http://dx.doi.org/10.1210/jc.2011-0385 through http://dx.doi.org. Accessed August 2011.
Brett A. Evaluation, Prevention and Treatment of Vitamin D Deficiency. Journal Watch General Medicine June 23, 2011. Available online at http://general-medicine.jwatch.org/cgi/content/full/2011/623/1 through http://general-medicine.jwatch.org. Accessed August 2011.
Institute of Medicine. Report at a Glance: Dietary Reference Intakes for Calcium and Vitamin D. Available online at http://www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/Report-Brief.aspx?page=1 through http://www.iom.edu. Accessed August 2011.