Specimen:

Plasma

Collection Medium:

Alternate
Collection Media:

Call laboratory for additional acceptable specimen collection 
containers.

Minimum:

0.5 mls plasma from light green top tube or one 0.6 microtubes

Testing
Schedule:

24 hrs/day, 7 days a week, including holidays.

Analytic Time:

2 hours (upon receipt in laboratory)

Reference Range:

Adult male:   2.2 - 5.0 mg/L
Adult female: 1.9 - 4.4 mg/L

Comments:

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.

Hemolysis:  No significant interference from hemoglobin up to an
            H index of 1000.

Lipemia (Intralipid):  No significant interference from lipemia
                       up to an L index of 1000.

Interference studies were performed using the Roche/Hitachi 917 
analyzer and NCCLS EP7-P Interference Testing in Clinical Chemistry 
protocol or a dose-response curve.

Level of Transferrin
Interferent               Interferent Conc.     Effect
                         mg/dL (mg/L)(mg/L)  Significant?*
Bilirubin                 58.5  6.83-0.10         no
Hemoglobin                1000  6.74-0.06         no
Lipemia (Intralipid)      1000  6.78-0.23         no

*The criteria for determining no significant interference in the sample 
is that the sample with the interfering substance recovers within plus 
or minus 10% of the baseline value.

No high-dose hook effect up to sTfR concentrations of 80 mg/L.

Rheumatoid factors < 750 IU/mL do not interfere.

Methodology:

Immunoturbidometric Assay

Sample
Processing:

Centrifuge at 3000 RPM for 10 minutes.
Aliquot plasma into labeled container and cap.

Sample
Storage:

Refrigerate.

Transport
Instructions:

Place requisition into outside pocket of bag.
Place specimen into zip-lock type bag, seal bag.
Transport in cooler with refrigerated coolant packs.

CPT Code:

84238