Anemia or low blood is present in up to 20% of children at some time during their childhood.
Some physicians think childhood anemia is almost always caused from iron deficiency, but a 2005 study called that into question, finding anemia was common in children with adequate iron stores and that most children with iron deficiency did not have anemia.
So what causes anemia in childhood?
While there are many potential causes, it appears that much of the anemia of childhood is idiopathic, meaning the cause is unknown.
In a recent study, Dr. Meredith Atkinson, working under senior author Professor Jeffrey Fadrowski of the Johns Hopkins University School of Medicine, may have helped answer some of these questions. They are the first to discover that vitamin D levels are correlated with childhood anemia.
They studied more than 10,000 children (average age 12) from NHANES III, a large group of Americans who represent the population at large. They found that the overall prevalence of anemia in children was 4%, but this dramatically differed by race, with 2% of white children being anemic and 14% of black children (P < .001).
The median 25(OH)D level (as measured by Diasorin RIA) was 27 ng/ml in the white children but only 17 ng/ml among black children. RIA tends to overestimate 25(OH)D levels, but the relative contrast between dark-skinned and light skinned children was stark.
For all children, the odds ratio (OR) for anemia for those with 25(OH)D levels less than 30 ng/mL, compared with 25(OH)D over 30 ng/mL, was almost 2 (P = .006). Furthermore, even when they controlled for iron status (measured in a subgroup of 2,700 children), they found those children with a 25(OH)D less than 30 ng/mL compared with over 30 ng/mL still continued to have an increased risk for anemia (OR 3.5, P = .016).
Finally, they found something else that was very interesting. They found the cutoff or threshold for the relationship between 25(OH)D and anemia was 20 ng/ml for the white children but only 11 ng/ml for the black children. They speculated that the percentage of bioavailable 25(OH)D was higher in black children, which may account for these different cutoffs.
The authors did not speculate whether childhood anemia may be caused by vitamin D deficiency. Future research should elucidate if getting enough vitamin D can reduce childhood anemia.