Soluble Transferrin Receptor (sTfR) and sTfR/log Ferritin Index for the Diagnosis of Iron-Deficiency Anemia

Determination of serum soluble transferrin receptor (sTfR) is proposed to distinguish between iron-deficiency anemia and anemia of chronic disease. Here we conducted a meta-analysis of the literature to evaluate the diagnostic efficacy of sTfR and sTfR/log ferritin index. The meta-analysis included 18 sTfR and 10 sTfR index studies. Three sTfR index studies were, however, eliminated as outliers. The odds ratio was significant for both sTfR (22.9, 95% confidence interval [CI], 9.6-55.0) and sTfR index (9.5, 95% CI, 5.0-18.1) in a heterogeneous set of studies. Meta-analysis for sensitivity, specificity, and likelihood ratios (LRs) was performed only in a subset of 10 sTfR studies. The overall sensitivity, specificity, and positive and negative LRs were 86%, 75%, 3.85, and 0.19, respectively, with an area under summary receiver operating characteristic curve of 0.912 (standard error, 0.039). Additional studies are needed to define the overall diagnostic accuracy of sTfR.