Relationship between serum 25-hydroxyvitamin D and red blood cell indices in German adolescents

Since the impact of vitamin D on red blood cell formation has not been well studied, we aimed at assessing the putative link between serum 25-hydroxyvitamin D (25[OH]D) concentrations and hematological markers of erythropoiesis in a large cohort of German adolescents aged 11 to 17 years. In total, 5066 participants from the population-based, nationally representative KiGGS study (Kinder- und Jugendgesundheitssurvey, German Health Interview and Examination Survey for Children and Adolescents) were grouped into either tertiles or clinically accepted cutoff levels for serum 25(OH)D. Results demonstrated significant and inverse correlations between 25(OH)D levels and several hematological parameters including hemoglobin concentration (r = - 0.04, p = 0.003), mean corpuscular hemoglobin (r = - 0.11, p < 0.001), red blood cell count (r = - 0.04, p = 0.002), and soluble transferrin receptor (r = - 0.1, p < 0.001), whereas, in contrast, serum 25(OH)D was positively correlated to the mean corpuscular volume of erythrocytes (r = 0.08, p < 0.001). Multinomial regression models adjusted for clinically relevant confounders confirmed statistically significant differences between the two strata of 25(OH)D groups with respect to red blood cell markers (hemoglobin concentration, red blood cell count, mean corpuscular volume, and corpuscular hemoglobin, as well as iron and soluble transferrin receptor). Conclusions: The link between serum 25(OH)D and several important hematological parameters may point to an inhibitory role of vitamin D in the regulation of erythropoiesis in adolescents. What is Known: The physiological effects of vitamin D on calcium homeostasis and bone metabolism have been established. However, much less is known about the impact of circulating vitamin D on erythropoiesis. What is New: Data from the KiGGS study in German adolescents demonstrated significant associations between serum vitamin D concentrations and red blood cell indices. Further studies should be conducted to decipher the underlying mechanisms of vitamin D on erythropoiesis.