Relationship between transferrin saturation and iron stores in the AfricanAmerican and US Caucasian populations: analysis of data from the third National Health and Nutrition Examination Survey

In previous analyses of transferrin saturation data in African Americans an d Caucasians from the second National Health and Nutrition Examination Surv ey (NHANES II), subpopulations were found consistent with population geneti cs for common loci that influence iron metabolism. The goal of this new stu dy was to determine if these transferrin saturation subpopulations have dif ferent levels of iron stores. Statistical mixture modeling was applied to t ransferrin saturation data for African Americans and Caucasians from the th ird National Health and Nutrition Examination Survey (NHANES III), and then the mean serum ferritin concentrations were determined for the transferrin saturation subpopulations that were identified. After adjustment for diurn al variation, 3 subpopulations of transferrin saturation were identified in each racial group. Satisfying Hardy-Weinberg conditions for major locus ef fects, in both racial groups the sum of the square roots of the proportion with the lowest mean transferrin saturation and the proportion with the hig hest mean transferrin saturation was approximately 1. When weighted to refl ect the US adult population as a whole, these subpopulations of increasing transferrin saturations had progressively increasing mean age-adjusted seru m ferritin concentration values in each ethnic grouping as stratified by se x (trend test, P <.002 for all). These results are consistent with the conc ept that population transferrin saturation subpopulations reflect different levels of storage (C) 2001 by The American Society of Hematology.