Serum soluble transferrin receptor and the prediction of marrow aspirate iron results in a heterogeneous group of patients

Serum soluble transferrin receptor (sTfR) concentration has been evaluated in the diagnosis of iron deficiency in otherwise healthy individuals and in patients with rheumatoid arthritis, but has not been studied in a general population of patients with complicated clinical presentations. In this stu dy, 145 anaemic patients with a variety of medical conditions undergoing di agnostic bone marrow aspiration for any reason were tested by a complete bl ood count, a panel of biochemical tests to evaluate iron status, bone-marro w aspirate iron stain, and serum sTfR concentration. Sixteen per cent lacke d stainable iron in the marrow aspirate. All biochemical parameters differe d significantly between patients with or without stainable marrow iron. The sTfR assay was significantly more sensitive but less specific than other i ron status assays in identifying the absence of stainable iron. Logistic re gression analysis demonstrated that only sTfR and ferritin contributed inde pendently to the prediction of marrow iron status. Serum ferritin alone was highly specific but insensitive. A decision algorithm combining serum ferr itin and sTfR was as sensitive as TfR and as specific as serum ferritin. Th e measurement of serum sTfR, especially in conjunction with serum ferritin, is a valuable addition to the existing methods for predicting the results of marrow aspirate iron stains.