Components of the difference in hemoglobin concentrations in blood between black and white women in the United States.

Hemoglobin and the per cent transferrin saturation (TS) distributions of 742 black and 3074 white women drawn from a large probability sample of the US civilian noninstitutionalized population (HANES I) were examined to ascertain the magnitude and nature of an observed systematic difference in hemoglobin levels. This significant hemoglobin difference was primarily related to a different relationship between hemoglobin and TS for blacks and whites, and not related to differences in TS between the races. This difference between the races in the relationship between hemoglobin and TS explained almost all of the difference in hemoglobin concentration at the mean, the median and higher percentiles, and half or more of the difference at the first and third percentiles of the cumulative hemoglobin distributions of the white and black populations sampled. The practical implication of these findings is that white hemoglobin diagnostic criteria (standards) are inappropriate for blacks, and vice versa, both at the mean and at the lower hemoglobin levels of clinical interest.