Impact of acute malaria on plasma concentrations of transferrin receptors

The acute-phase response to infection alters the plasma concentrations of most biochemical measures of iron status, rendering assessment of status difficult. Soluble transferrin receptors (TfR) may be an exception but have not been examined longitudinally during the major metabolic and inflammatory changes which occur during clinical malaria. Blood samples were collected daily during hospitalization, and again at a follow-up 2-6 weeks after discharge, from adult, mainly European, patients (n = 49) who developed uncomplicated Plasmodium-falciparum malaria following visits to endemic areas. Parasitaemia and plasma concentrations of ferritin, TfR, C-reactive protein (CRP), alpha(1)-acid glycoprotein (AGP) and alpha(1)-antichymotrypsin (ACT) were measured. The concentrations of CRP, AGP and ACT correlated highly (P < 0.001) with each other and with plasma ferritin, and were significantly higher (P < 0.05) at all time points in hospital compared to the follow-up. TfR concentration correlated negatively and significantly (P < 0.05) with AGP and CRP but not with ACT or ferritin, and was significantly lower (around 30%) at all time points in hospital compared to follow-up, although in only 1 subject did it ever fall outside the normal reference range. In areas where both iron deficiency and clinical episodes of malaria are common, plasma TfR values need to be interpreted cautiously as indicators of iron status.