The Hopkins-led study involved 429 children ages 1 to 16 with chronic kidney disease enrolled in 44 study sites across the United States. More than 40 percent of black children had hemoglobin levels below the fifth percentile for their age and gender - deemed a critical cutoff point - compared to 29 percent of white children. Also, fewer African-American than white children reached higher hemoglobin levels with treatment. The differences persisted even after researchers controlled for factors affecting hemoglobin levels, such as an iron-rich diet and body-mass index.

Moreover, researchers found that as the disease progressed and the anemia got worse across the board for all children, the hemoglobin gap between white and black children widened. This finding suggests that as the disease progresses, pediatric nephrologists should monitor even more vigilantly hemoglobin levels in their African-American patients.

"What we are observing could very well mean that black children's hemoglobin levels start to plummet once they reach a certain point in their disease," Atkinson said.

Untreated, chronic anemia can speed disease progression and, over time, can lead to a dangerous thickening of the heart muscle called left-ventricular hypertrophy, among other complications.

Chronic kidney disease affects 26 million people in the United States.

Source: Johns Hopkins Medical Institutions