Plasma Concentrations of Hepcidin in Anemic Zimbabwean Infants

Abstract

Objective: Anemia in infancy is a global public health problem. We evaluated the relative contributions of iron deficiency and inflammation to infant anemia.

Methods: We measured plasma hepcidin, ferritin, soluble transferrin receptor (sTfR), alpha-1-acid glycoprotein and C-reactive protein (CRP) by ELISA on archived plasma from 289 HIV-unexposed anemic or non-anemic Zimbabwean infants at ages 3 mo, 6 mo and 12 mo. Among anemic infants, we determined the proportion with iron-deficiency anemia (IDA) and anemia of inflammation (AI). We undertook regression analyses of plasma hepcidin and anemia status, adjusting for sex, age and birthweight.

Results: Anemic infants at 3 mo were more stunted and had higher CRP (median 0.45 vs 0.21 mg/L; P = 0.037) and hepcidin (median 14.7 vs 9.7 ng/mL; P = 0.022) than non-anemic infants, but similar levels of ferritin and sTfR; 11% infants had IDA and 15% had AI. Anemic infants at 6 mo had higher hepcidin (median 7.9 vs 4.5 ng/mL; P = 0.016) and CRP (median 2.33 vs 0.32 mg/L; P<0.001), but lower ferritin (median 13.2 vs 25.1 μg/L; P<0.001) than non-anemic infants; 56% infants had IDA and 12% had AI. Anemic infants at 12 mo had lower ferritin (median 3.2 vs 22.2 μg/L; P<0.001) and hepcidin (median 0.9 vs 1.9 ng/mL; P = 0.019), but similar CRP levels; 48% infants had IDA and 8% had AI. Comparing anemic with non-anemic infants, plasma hepcidin was 568% higher, 405% higher and 64% lower at 3 mo, 6 mo and 12 mo, respectively, after adjusting for sex and birthweight (all p<0.01). Plasma hepcidin declined significantly with age among anemic but not non-anemic infants. Girls had 61% higher hepcidin than boys, after adjusting for age, anemia and birthweight (p<0.001).

Conclusion: Anemia is driven partly by inflammation early in infancy, and by iron deficiency later in infancy, with plasma hepcidin concentrations reflecting the relative contribution of each. However, there is need to better characterize the drivers of hepcidin during infancy in developing countries.

Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1. Selection of infants into the hepcidin substudy.

¶ HIV-unexposed infants with gestational age >37 weeks, birth weight > 2500 g and available plasma samples (>120 μL). *Non anemic infants were selected based on no abnormal iron indicators (defined as hemoglobin < 105 g/L at 3 and 6 months and < 100 g/L at 12 months, serum ferritin < 12 μg/L, sTfR > 8.3 mg/L), no evidence of inflammation (defined as AGP > 1 g/L or CRP > 5 mg/L) and no acute illness (defined as diarrhea or fever in the prior week or measles in the prior 3 months). Anemic infants at each age were randomly selected from 62, 77 and 85 eligible infants at 3, 6 and 12 months based on hemoglobin (defined as <105 g/L at 3 and 6 months, and <100 g/L at 12 months of age.

Fig 2. Biomarker concentrations in anemic and non-anemic infants.

Graphs show the plasma concentrations of hepcidin, ferritin, soluble transferrin receptor and C-reactive protein (CRP) in infants at (A) 3 months, (B) 6 months and (C) 12 months of age. The boxes indicate the 25th and 75th percentiles and the horizontal line indicates the median. Hepcidin, ferritin and CRP are expressed on a log scale. Full data for each biomarker are also shown in Table 2.

Fig 3. Relationships between hepcidin and other biomarkers.

Correlations between (A) plasma hepcidin and ferritin and (B) plasma hepcidin and CRP. Values for non-anemic (empty circles) and anemic (solid circles) infants are combined (p