BACKGROUND: The soluble transferrin receptor (sTfR) is established as a test for iron deficiency (ID). In chronic lymphocytic leukemia (CLL), sTfR is not reliable for screening for ID as the latter is strongly dependent on tumor burden. METHODS: We investigated whether the influence of the tumor load can be excluded or minimized using the sTfR/log ferritin ratio (TfR-F-Index) and the C-reactive protein (CRP)-adjusted TfR-F-Index in 87 patients with CLL. sTfR was measured nephelometrically (normal: 0.81-1.75 mg/L). A cut-off value of 1.5 for the TfR-F-Index and 0.8 for the CRP-adjusted TfR-F-Index, in patients with a CRP >5 mg/L, was used. RESULTS: All Binet A patients had normal sTfR values (1.34+/-0.2 mg/L), TfR-F-Index (0.67+/-0.2) and a CRP-adjusted TfR-F-Index. In Binet B and C, sTfR and the TfR-F-Index were significantly increased compared to Binet A patients (p
