Association of serum transferrin receptor concentration with markers of inflammation in Zimbabwean children

Abstract

Background: Clinical studies have shown that degree of erythropoiesis, the hypoxic response, and iron status each independently influences transferrin receptor concentration, but there is conflicting information regarding the effect of inflammation on transferrin receptor expression.

Subjects and methods: Levels of hemoglobin, reticulocytes, serum ferritin, transferrin receptors and inflammatory markers (C-reactive protein, interleukin-6 and neutrophils) were determined in 208 Zimbabwean children <or=5 years attending well-child clinics in a non-malaria transmission, non-hookworm area.

Results: In linear regression models among 147 children with ferritin >10 ng/mL that adjusted for erythropoiesis with log(10) reticulocyte count, the hypoxic response with hemoglobin concentration and iron status with log(10) ferritin concentration, positive correlations were found between log(10) transferrin receptor concentration and log(10) C-reactive protein concentration (P=0.012), log(10) interleukin-6 concentration (P=0.011) and log(10) neutrophil count (P=0.013). These models predict that, with a baseline transferrin receptor concentration in the upper normal range of 8.0 mg/L and holding hemoglobin concentration and reticulocyte count constant, an increase from 1 to 10 mg/L in C-reactive protein is associated with a rise of 1.6 mg/L in transferrin receptor (95% C.I. 0.3-3.0 mg/L), an increase from 0.5-to-5.0 pg/mL in interleukin-6 with a rise of 1.9 mg/L (0.4-3.7 mg/L), and an increase from 2000 to 20,000/microL in neutrophil count with a rise of 3.6 mg/L (0.7-7.5 mg/L).

Conclusion: Our results suggest that inflammation leads to an increase in circulating transferrin receptor concentration that is independent of the degree of erythropoiesis, the hypoxic response and iron status.