Posted June 1, 2009
Vitamin D deficiency typically results when the body is not exposed to enough sunlight or doesn’t receive enough sources of nutritional vitamin D, including fortified milk and cereal. Untreated, pediatric vitamin D deficiency can lead to rickets (malformation of the bones), and adult deficiency can lead to hypertension, cardiovascular disease and insulin resistance. With the prevalence of vitamin D deficiency ranging from 15%80%, the medical community is rethinking the definition of this pediatric condition.
The wide range of vitamin D deficiency incidence is a function of its broad definition, which is based on an optimal vitamin D level. The current cut-off for a diagnosis of vitamin D deficiency is a serum blood level of less than 11 ng/mL, but many experts now think the cut-off should be higher, at less than 20 ng/mL (ng = nanogram, which is one billionth of a gram). In fact, many practioners seem to be diagnosing vitamin D deficiency when a child’s serum blood level is not clinically deficient (less than 11 ng/mL) but merely inadequate (for example, less than 20 ng/mL), a practice that has contributed to the huge range in incidence.
In a recent study looked at blood serum levels of children age 1219 who had participated in the National Health and Nutrition Examination Survey III, the average reading was 32 ng/mL. The overall prevalence of vitamin D deficiency increased from 2% to 14% when the deficiency definition increased from the current less than 11 ng/ mL standard to the proposed less than 20 ng/mL. Most significantly, non-hispanic black adolescents had 20 times the odds of having a serum level of less than 20 ng/mL than non-hispanic white adolescents, and their prevalence of the deficiency increased from 11% to 50% when the definition was raised.
Lead researcher Sandy Saintonge, MD of Weill Cornell Medical College Department of Public Health and her colleagues also found additional risk factors for vitamin D deficiency when the serum level was raised to less than 20 ng/mL. Girls had more than twice the odds than boys, overweight children had 1.75 times the odds than average-weight children, children in the South had more than twice the odds than children in the Midwest, urban children had more than oneand-a-half times the odds than rural children, children from lowincome families had almost three times the odds than children from high-income families, and children who had only completed grade nine, ten or eleven had more than twice the odds than those who were in college.
With many demographic groups, including half the U.S. non-hispanic black population, at possible risk of vitamin D deficiency, Saintonge concluded that children should continue to receive vitamin D supplements, and their blood serum levels be monitored.
The Food and Nutrition Board of the National Academies recommends that people take a daily dose of 5 meg (or 200 International Units) of vitamin D from birth through age 50, then 400 IU through age 70, and 600 IU after that to maintain optimal bone health and calcium metabolism. The American Academy of Pediatrics goes even further and recommends that infants through adolescents need 400 IU daily.
Pediatrics, 3/09
Date: May 20, 2009