Race Differences in Erythropoietin, 25‐hydroxyvitamin D, and Hemoglobin Before and After Weight Loss in Women

Abstract

Low hemoglobin (Hb) is a predictor of cardiovascular disease, thus, variables known to influence Hb are of clinical relevance. We examined the interrelationships of testosterone, erythropoietin (EPO), 25‐hydroxyvitamin D [25(OH)D] and Hb before and after weight loss. Overweight African American (AA) and European American (EA) women were provided a standardized 800 kcal/d diet for the purpose of reducing BMI < 25 kg/m2. Physiological measures and blood sampling were performed at baseline and upon reaching target BMI. Testosterone was similar between races before and after weight loss. Yet, Hb (AA, 11.6 ± 0.9 g/dL vs. EA, 12.5 ± 0.8 g/dL; P < 0.01) and 25(OH)D (AA, 14.2 ± 5.4 nmol/L vs. EA, 19.6 ± 5.9 nmol/L; P < 0.01) were lower while EPO was higher (AA, 14.3 ± 9.8 mIU/mL vs. EA, 7.9 ± 2.4 mIU/mL; P < 0.01) in AA women compared to EA women at baseline. Following weight loss, Hb was significantly decreased in both races (AA, ‐0.5 ± 0.7 g/dL vs. EA, ‐0.4 ± 0.6 g/dL; P < 0.01). Additionally, 25(OH)D (AA, +3.3 ± 5.4 nmol/L vs. EA, +4.5 ± 6.7 nmol/L; P < 0.05) and EPO (AA, +10.0 ± 23.8 mIU/mL vs. EA, +0.9 ± 4.5 mIU/mL, P < 0.01) were increased in both races. Changes in Hb from baseline to weight loss were positively associated with changes in 25(OH)D (r = 0.35; P < 0.01) and negatively associated with changes in EPO (r = ‐0.72; P < 0.01). Hb decreased as 25(OH)D and EPO increased with controlled weight loss among AA and EA women. Despite higher EPO, AAs had lower Hb that may have been mediated by lower 25(OH)D. Given the extent Hb was decreased, a large proportion of women particularly AA, were below the accepted threshold (< 12 g/dL) for anemia.