Specimen Collection

Sample stability:

• 1 day at 20-25 ^o C
• 8 days at 4-8 ^o C
• 3 months at -20 ^o C

4.5 mL PST Blood (Preferred)

0.5 mL Paediatric Micro-PST Blood (Preferred)

5 mL Adult Heparin Blood

4 mL Adult Plain Blood

3.5 mL SST Blood

2 mL Paediatric Microsample Blood

2 mL Paediatric Micro-heparin Blood

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Reference Intervals

Units: kIU/L

0 -14

Uncertainty of measurement: 6%

Turnaround Time: Within 3 hours

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Assay Method

Principle: Immunoturbidometric assay

Reagents: Roche Tina-Quant RF II

Analyser: Cobas c502

Diagnostic Use and Interpretation

Rheumatoid factors are antibodies directed against antigenic determinants on the Fc fragment of IgG.

Low titres of rheumatoid factor occur in approximately 5% of the healthy adult population, and are more common with increasing age.

Rheumatoid factor is positive in about 70% of patients with rheumatoid arthritis, and may be positive in up to 15-20% of other autoimmune rheumatic diseases, e.g. SLE, and also in some non-rheumatic diseases with variable frequency, e.g. subacute bacterial endocarditis (40%) Waldenstrom's macroglobulinaemia (30%), infectious hepatitis (25%), liver cirrhosis (25%) and pulmonary interstitial disease (25%).

Rheumatoid factor is positive in 15 - 20% of elderly subjects with other chronic disease states.

It has prognostic value when present in rheumatoid arthritis, with high titres being associated with more severe disease and an unfavourable outcome.

Also See:

Anti-cyclic citrullinated peptide (Anti-CPP)

Contact Information

Associate Professor Rohan Ameratunga , Immunopathologist: Ext 22106 Locator 93-5724

Emails to chemicalpathologist@adhb.govt.nz will receive priority attention from the on-call chemical pathologist.

If the query concerns a specific patient please include the NHI number in your email.

If email is not a suitable option, please contact the on-call chemical pathologist via Lablink (Auckland City Hospital ext. 22000 or 09-3078995).

Individual chemical pathologists may be contacted but will not be available at all times.

After-hours : contact Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours.

Dr Samarina Musaad (Clinical Lead) : SamarinaM@adhb.govt.nz ext. 22402

Dr Cam Kyle: CampbellK@adhb.govt.nz ext 22052

Dr Weldon Chiu: WeldonC@adhb.govt.nz ext. 23427

Dr Campbell Heron: CHeron@adhb.govt.nz ext. 23427

Dr Sakunthala Jayasinghe: Sakunthala@adhb.govt.nz ext. 23427

Last updated at 15:26:00 06/01/2025