BOSTON – Healthy individuals do not need to be screened for vitamin D deficiency, according to guidelines released today by the Endocrine Society.
"We do not recommend screening for vitamin D deficiency in individuals not at risk. That's an important message. So we're recommending screening for those at risk for vitamin D deficiency – those who are obese, African Americans, pregnant and lactating women, patients with malabsorption syndromes, and a whole list that we have provided in the guidelines," lead author Dr. Michael F. Holick said at the annual meeting of the Endocrine Society.
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Only those at risk for vitamin D deficiency should be screened, new guidelines advise.
Dr. Holick headed a task force appointed by the clinical guidelines subcommittee of the Endocrine Society to formulate evidence-based recommendations on vitamin D deficiency. The subcommittee deemed vitamin D deficiency a priority area in need of practice guidelines.
The task force noted that most individuals do not get adequate vitamin D for a number of reasons. In particular, "there needs to be an appreciation that unprotected sun exposure is the major source of vitamin D for both children and adults and that in the absence of sun exposure it is difficult, if not impossible, to obtain an adequate amount of vitamin D from dietary sources without supplementation to satisfy the body’s requirement. Concerns about melanoma and other types of skin cancer necessitate avoidance of excessive exposure to midday sun," they wrote.
The task force recommended that those at risk for vitamin D deficiency be screened by measuring serum 25-hydroxyvitamin D levels using a reliable assay. Causes of vitamin D deficiency include obesity, fat malabsorption syndromes, bariatric surgery, nephrotic syndrome, a wide range of medications (anticonvulsants and anti–HIV/AIDS drugs), chronic granuloma-forming disorders, some lymphomas, and primary hyperthyroidism.
The guidelines were released at the meeting and will be published in the July issue of the Journal of Clinical Endocrinology & Metabolism (doi: 10.1210/jc.2011-0385).
The guidelines provide long-awaited recommendations on vitamin D intake and the diagnosis and treatment of vitamin D deficiency. Physicians have struggled for years to delineate how much vitamin D is necessary for different clinical groups, how to measure it, and how best to supplement deficiencies.
The task force commissioned the conduct of two systematic reviews of the literature to inform its key recommendations and followed the approach recommended by GRADE, an international group with expertise in development and implementation of evidence-based guidelines.
"All available evidence suggests that children and adults should maintain a blood level of 25(OH)D above 20 ng/mL to prevent rickets and osteomalacia, respectively. However, to maximize vitamin D's effect on calcium, bone, and muscle metabolism, the 25(OH)D blood level should be above 30 ng/mL," the group wrote.
In the new guidelines, vitamin D deficiency is defined as a 25(OH)D concentration less than 20 ng/mL (50 nmol/L). The task force suggests:
– Infants and children aged 0-1 year require at least 400 IU/day (IU = 25 ng) of vitamin D to maximize bone health.
– Children 1 year and older require at least 600 IU/day.
– Adults aged 19-50 years require at least 600 IU/day.
– Adults aged 50-70 years require at least 600 IU/day.
– Adults 70 years and older require 800 IU/day.
– Pregnant and lactating women require at least 600 IU/day.
The task force also recommends that obese children and adults and children and adults on certain medications (anticonvulsant medications, glucocorticoids, antifungals such as ketoconazole, and medications for AIDS) be given at least 2-3 times more vitamin D for their age group to satisfy their bodies' vitamin D requirements.
Either vitamin D2 or vitamin D3 can be used for the treatment and prevention of vitamin D deficiency. The group recommends that adults who are vitamin D deficient be treated with 50,000 IU of vitamin D2 or vitamin D3 once a week for eight weeks or its equivalent of 6,000 IU of vitamin D2 or vitamin D3 daily to achieve a blood level of 25(OH)D greater than 30 ng/mL. This should be followed by maintenance therapy of 1,500-2,000 IU/day.
The task force also recommends vitamin D supplementation for fall prevention. "We know that there is sufficient evidence to give vitamin D for fall prevention. It's well documented that vitamin D is very important for muscle strength," said Dr. Holick, professor of medicine, physiology and biophysics at Boston University.
However, the group does not recommend prescribing vitamin D supplementation beyond recommended daily needs for the purpose of preventing cardiovascular disease or death or improving quality of life, because there is insufficient evidence.