Serum transferrin receptor concentrations in women with mild malnutrition

We determined the influence of undernutrition on blood soluble transferrin receptor (sTfR) concentrations, an indicator of iron deficiency, in 99 Zairean women (aged 16-45 y) without inflammation. They were recruited during a survey on iron deficiency in rural Bas-Zaire. sTfR was measured by enzyme immunoassay, and indicators of nutritional status [albumin, transthyretin (or prealbumin), and retinol binding protein] were measured by radial immunodiffusion. Undernutrition was diagnosed if the concentration of any one of the indicators was below normal: albumin < 35 g/L, transthyretin < 160 mg/L, and retinol binding protein < 30 mg/L. The sTfR concentration ranged from 1.89 to 19.1 mg/L (mean: 8.7 mg/L). Mean values for indicators of nutritional status, serum ferritin, and transferrin saturation were within the normal range for health subjects. Regardless of the iron status (iron sufficiency, anemia, or iron deficiency with or without anemia) and whether women were pregnant or nonpregnant, undernutrition did not significantly reduce sTfR concentrations. A higher percentage (80%) of iron-deficient women with two or three protein values below normal had sTfR concentrations > 8 mg/L (which are suggestive of iron-deficiency erythropoiesis) compared with iron-deficient women with no (72.7%) or one (66.7%) protein value below normal, anemic women (46-60%) and iron-sufficient women (18.2-36.8%). Results suggest that sTfR can be used as an indicator of iron deficiency in field studies without in-depth assessment of nutritional status. However, the effect of severe malnutrition on this index requires further investigation.