University of Iowa
Diagnostic Laboratories
(UIDL) Test Directory

319-384-7212 (local)
1-866-844-2522 (toll free)


Rheumatoid Factor Order Code: RF
Order Form: Laboratory Requisition
Specimen:
Plasma
Collection Medium:
Plasma separator tube
Alternate
Collection Media:
Call laboratory for additional acceptable specimen collection 
containers.
Minimum:
5 ml; whole blood in light green top tube
Testing
Schedule:
24 hrs/day, 7 days a week, including holidays.
Analytic Time:
2 hours (upon receipt in laboratory)
Reference Range:
<14 IU/ml
Test
Limitations:
Criterion: Recovery within plus or minus 10% of initial value.

Icterus: No significant interference up to an I index of 60 
(approximateconjugated and unconjugated bilirubin concentration: 60 
mg/dl or 1026 umol/l).

Hemolysis: No significant interference up to an H index of 1000 
(approximate hemoglobin concentration: 1000 mg/dl or 621 umol/l).

Lipemia (Intralipid): No significant interference up to an L index of 
500.

There is poor correlation between turbidity and triglycerides 
concentration.

No high-dose hook effect up to RF activities of 6000 IU/ml.

Thirty one commonly used pharmaceuticals were tested in vitro. No 
interference with the assay was found.

Reference:
Glick MR, Ryder KW, Jackson SA. Graphical Comparisons of Interferences 
in Clinical Chemistry Instrumentation. Clin Chem 1986;32:470-474.
Methodology:
Immunoturbidimetric Assay
Sample
Processing:
Centrifuge at 3000 RPM for 10 minutes.
Aliquot plasma into labeled container and cap.
Sample
Storage:
Refrigerate.
Transport
Instructions:
Place specimen into zip-lock type bag, seal bag.
Place requisition into outside pocket of bag.
Transport in cooler with refrigerated coolant packs.
CPT Code:
86431

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Updated: 06/24/2005