[Multiparametric analysis for the diagnosis of iron deficiency anemia]

The serum transferrin receptor (sTR) as a marker of iron depletion was evaluated in two groups: 50 normal adults of both sexes living at sea level and 50 iron deficiency anemias (secondary to nutritional, gastrointestinal or gynecologic diseases). Mean values were 16.6 nmol/L (interval of reference 8.8 to 26.2), for controls, without variations related to age and sex, and 66.3 nmol/L (16.1 to 148.8) for anemic patients. Statistical analysis (receiver operating characteristics, ROC) determined an optimal reference interval of 8.8 to 25.8 nmol/L. Predictive values as a diagnostic tool were 97.5%, PV (+) and 97.7%, PV (-); diagnostic efficiency was 97.7%. In both controls and anemics it was observed: 1) an inverse relationship between sTR and serum ferritin (F) (r2 72%; p < 0.001); 2) wide variations of sTR when plasma hemoglobin (Hb) was < 100 g/L (r2 71%; p < 0.001); 3) values for the sTR/logarithm of serum ferritin ratio (sTR/F index) much higher in anemics (75.8) than in controls (9.6). In the former group, iron supplementation normalized sTR levels but did not change ferritin values. We conclude that sTR is a specific and sensitive index of functional iron deficiency and therefore a quick, accurate and non invasive quantitative parameter for the diagnosis of iron deficient erythropoiesis.