Evaluation of an automated soluble transferrin receptor (sTfR) assay on the Roche Hitachi analyzer and its comparison to two ELISA assays.
BACKGROUND
Soluble transferrin receptor (sTfR) assays are currently not standardized. This hinders data comparison between studies and also affects the use of a recently proposed model to estimate body iron.


METHODS
We evaluated the analytical performance of a fully automated sTfR immunoturbidimetric assay (Roche Diagnostics) and compared it with two ELISA assays (Ramco Laboratories and an in-house ELISA assay used in the body iron model).


RESULTS
The Roche assay showed excellent intra- and inter-assay precision (CV<5%). Prolonged exposure of serum samples to room temperature and multiple freeze-thaw cycles did not affect sTfR concentrations. Receiver-operator characteristic curve analysis demonstrated that the Roche assay (area-under-the-curve (AUC)=0.882) was superior to the Ramco assay (AUC=0.794) in predicting iron deficiency (defined as serum ferritin <10 microg/L; P=0.013). Method comparison between the Roche and the two ELISA assays showed good correlations (r>0.8); however, sTfR values by the Roche assay were on average 30% lower than values obtained with the two ELISA assays.


CONCLUSIONS
sTfR data measured with an immunoturbidimetric assay can be compared to a commonly used ELISA assay, and can be used in the body iron model through regression equations obtained in the present study.
Pfeiffer
Christine M
CM
Centers for Disease Control and Prevention, National Center for Environmental Health, Atlanta, GA 30345, USA. cpfeiffer@cdc.gov
Cook
James D
JD
Mei
Zuguo
Z
Cogswell
Mary E
ME
Looker
Anne C
AC
Lacher
David A
DA
D001331:Automation; D019963:Clinical Chemistry Tests / Q000295:instrumentation*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D009391:Nephelometry and Turbidimetry / Q000295:instrumentation*; D012372:ROC Curve; D011933:Reagent Kits, Diagnostic; D011990:Receptors, Transferrin / Q000097:blood*; D015203:Reproducibility of Results
D011933:Reagent Kits, Diagnostic; D011990:Receptors, Transferrin