Mild increases in serum hepcidin and interleukin-6 concentrations impair iron incorporation in haemoglobin during an experimental human malaria infection

The correct selection of individuals who will benefit from iron supplements in malaria-endemic regions requires improved insight in the effects of malaria on host iron homeostasis and innovative biomarkers. We assessed sequential changes in serum hepcidin and in traditional biochemical iron status indicators during an experimental Plasmodium falciparum malaria infection with five adult volunteers. The haemoglobin content of reticulocytes (Ret-H-e) and of mature red blood cells (RBC-H-e) represented iron incorporation into haemoglobin. Low-density parasitaemia and its treatment induced a mild increase in interleukin (IL)-6 and serum hepcidin concentrations. Despite this only mild increase, a marked hypoferraemia with a strong increase in serum ferritin concentrations developed, which was associated with a sharp fall in Ret-H-e, while RBC-H-e remained unchanged. The ratio of soluble transferrin receptor (sTfR) to log ferritin concentrations decreased to an average nadir of 63% of the baseline value. We concluded that even mild increases in serum hepcidin and IL-6 concentrations result in a disturbed host iron homeostasis. Serum hepcidin, Ret-H-e and Delta-H-e (Ret-H-e minus RBC-H-e) are promising biomarkers to select those individuals who will benefit from iron supplements in malaria endemic regions, while the sTfR/log ferritin ratio should be used with caution to assess iron status during malaria.