title: The value of the Thomas-plot in the diagnostic work up of anemic patients referred by general practitioners.
abstract: In patients with inflammatory conditions, diagnosing classic iron deficiency or anemia of chronic disease is challenging. In this study, we assessed the diagnostic value of the so-called Thomas'-plot [soluble transferrin receptor (sTfR)/log ferritin (sTfr/log Ferr) and the reticulocyte hemoglobin equivalent (Ret-HE)] in the anemia work up of patients referred by general practitioners. During July 2008-March 2009, 337 consecutive patients were included because of lowered Hb values. The laboratory results of the first 133 consecutive patients were used to determine the cut-off values for the diagnostic plot. The laboratory results of these patients were assessed and interpreted independently by two investigators, blinded from sTfR/log Ferr and Ret-HE values. The following 204 patients were used to test the plot in practice. In 32% of the first 133 patients, no indication of the cause of anemia could be found. However, when using the diagnostic plot in the following 204 patients, this fraction decreased to 14%. The 'Thomas'-plot is of diagnostic value for distinguishing functional iron deficiency from classic iron deficiency in a patient population referred by general practitioners.
authors.affiliation: Department of Clinical Chemistry & Hematology, Atrium Medical Center Parkstad, The Netherlands. m.leers@atriummc.nl
authors.forename: M P G
authors.initials: MP
authors.lastname: Leers
authors.forename: J F W
authors.initials: JF
authors.lastname: Keuren
authors.forename: W P
authors.initials: WP
authors.lastname: Oosterhuis
mesh_terms: D000740:Anemia / Q000175:diagnosis*; D018798:Anemia, Iron-Deficiency / Q000175:diagnosis*; D015415:Biomarkers / Q000097:blood*; D005293:Ferritins / Q000032:analysis; D006454:Hemoglobins / Q000032:analysis; D007501:Iron / Q000097:blood; D000090463:Iron Deficiencies; D011990:Receptors, Transferrin / Q000032:analysis; D012016:Reference Values; D012156:Reticulocytes / Q000737:chemistry
chemical_list: D015415:Biomarkers; D006454:Hemoglobins; D011990:Receptors, Transferrin; D005293:Ferritins; D007501:Iron