The soluble transferrin receptor (TfR)-F-Index is not applicable as a test for iron status in patients with chronic lymphocytic leukemia.
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<0.0001). The differences between Binet B and C were not significant. sTfR was increased in 85%, TfR-F-Index in 46% and the CRP-adjusted TfR-F-Index in 54% of the Binet B patients, in Binet C patients, 80%, 50% and 60% showed increases, respectively. sTfR and the TfR-F-Index decreased or even normalized following successful treatment.


CONCLUSIONS
Similar to sTfR, the TfR-F-Index is strongly associated with tumor burden in patients with CLL. Thus, these parameters do not allow for a reliable diagnosis of ID in this patient group.
Metzgeroth
Georgia
G
III. Medizinische Klinik, Universitätsmedizin Mannheim, Universität Heidelberg, Mannheim, Germany.
Kripp
Melanie
M
Müller
Nadine
N
Schultheis
Beate
B
Bonatz
Karin
K
Walz
Christoph
C
Dorn-Beineke
Alexandra
A
Hastka
Jan
J
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002097:C-Reactive Protein / Q000378:metabolism; D005260:Female; D005293:Ferritins / Q000378:metabolism*; D006801:Humans; D007501:Iron / Q000378:metabolism*; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011990:Receptors, Transferrin / Q000737:chemistry* / Q000378:metabolism*; D012995:Solubility; D047368:Tumor Burden
D011990:Receptors, Transferrin; D002097:C-Reactive Protein; D005293:Ferritins; D007501:Iron