Soluble transferrin receptor as an index of iron status in Zaïrian children with malaria.

This study was designed to evaluate soluble transferrin receptor (sTfR) as an index of iron status in 0.5-16-year-old Zaïrian children: 17 with symptomatic malaria, 8 with asymptomatic malaria, and 15 controls. sTfR was also measured in 20 plasma samples obtained from iron sufficient laboratory employees. sTfR, haemoglobin and ferritin were measured by enzyme-immunoassay, cyanmethaemoglobin method, and radioimmunoassay respectively. Mean haemoglobin levels were lower and ferritin higher (P < 0.001) in children with clinical symptoms of malaria than in those without malaria, and they were intermediate in those with asymptomatic malaria. Mean sTfR concentrations were similar among the three groups of children and laboratory controls. There was a considerable overlap in sTfR concentrations between the three groups of children (1.8-10.2, 2.9-11.6 and 2.97-8.95 mg 1(-1) in symptomatic malaria, asymptomatic malaria and control groups, respectively) as well as laboratory controls (1.2-7.30 mg l-1). Despite the overlap, 6 children with malaria (24%) and one control child (6.7%) had sTfR concentrations above the highest concentration found in laboratory controls. No child had serum ferritin < 12 micrograms l-1 (suggestive of iron deficiency). As expected, sTfR negatively correlated with ferritin (r = -0.230) in the overall study population of children, and with haemoglobin in children with asymptomatic malaria (r = -0.943, P < 0.05), as well as in control children (r = -0.363). All children with sTfR above normal were also anaemic. Although the upper limit of normal sTfR concentration in healthy children is unknown, using the cut-off value of adults, we conclude that sTfR might be a more sensitive index of iron deficiency than serum ferritin in patients with malaria.