Soluble Transferrin Receptor
Label Mnemonic: STFR
Epic Lab Code: LAB906
Downtime Form: A-1a General Laboratory Requisition
6240 RCP
Collection Medium:
Plasma Separator Tube 4.5 mL
Alternate Collection Media:
Call laboratory for additional acceptable specimen collection containers.
3 mL from light green top tube or ONE Microtainer®.
Testing Schedule:
24 hrs/day, 7 days a week, including holidays.
Turn Around Time:
1 hour (upon receipt in laboratory)
Reference Range:
Adult male: 2.2 - 5.0 mg/L Adult female: 1.9 - 4.4 mg/L
The uptake of iron by the body's cells is controlled by expression of the transferrin receptor (TfR). If the intracellular iron stores are exhausted - corresponding to a ferritin concentration of less than 12 g/L - then more TfR is expressed. The affinity of the transferrin receptor to transferrin depends on the latter's loading state. As 80- 95% of the transferrin receptor molecules are localized on erythropoietic cells, the TfR concentration (and hence also the sTfR concentration) reflects the iron requirement of these cells. When iron deficiency exits, the sTfR concentration in serum rises even before the hemoglobin concentration is significantly depressed. The sTfR concentration status can be obtained by determining the sTfR index (=sTfR concentration/log ferritin concentration).
Test Limitations:
Icterus: No significant interference from bilirubin up to an I index of 60 (approximate conjugated and unconjugated bilirubin concentration of 60 mg/dL). Hemolysis: No significant interference from hemoglobin up to an H index of 800 (approximate hemoglobin concentration of 800 mg/dL). Lipemia (Intralipid): No significant interference from lipemia up to an L index of 1000. There is poor correlation between turbidity and triglycerides concentration. No high-dose hook effect up to sTfR concentrations of 80 mg/L. Rheumatoid factors < 750 IU/mL do not interfere.
Particle Enhanced Immunoturbidimetric Assay
CPT Code: