TODAYS PICK (8-07-2010)

Question history: AIPG-2002.
 
Rheumatoid factor in rheumatoid arthritis is important because
a)R.factor is associated with bad prognosis
b)Absent R.factor rules out the diagnosis of Rheumatoid arthritis
c)It is very common in child hood Rheumatoid arthritis
d)It correlates with disease activity .
 .
Ans:a

Discussion: ref.HARRISON 17th ED,2088 page

• A rheumatoid factor is autoantibody reactive against the Fc portion of IgG.
• Widely used laboratory tests generally recognise Igm type of rheumatoid factor
• Prescence of rheumatoid factor is not specific for Rheumatoid arthritis, as many other conditions are associated with positive Rheumatoid factor without Rheumatoid arthritis.
• Even 5% of the normal healthy population also have positive Rheumatoid factor.The frequency of Rheumatoid factor in general population increases with age and it is 10-20% in individualls above 65 years of age.

• Conditions associated with Positive Rheumatoid factor besides Rheumatoid arthritis. 

1. Systemic Lupus Erythematosis
2. Sjogren syndrome                  
3. Chr.Liver disease                   
4. Hepatitis-B                            
5. Sarcoidosis                            
6. Interstitial pulm.fibrosis           
7. Infectious Mononucleosis        
8. Tuberculosis                           
9. Leprosy                                  
10. Syphilis                                   
11. S.B.E                                     
12. Visce.leishmaniaisis                 
13. Schistosomiasis                       
14. Malaria                                   
15. Transiently after vaccination      
    

Summary: Rheumatoid factor is not useful as screening procedure .Hower it has pronostic significance. High titres indicate worse pronosis.

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