Main laboratory findings in Rheumatoid arthritis

 # What are the main laboratory findings in Rheumatoid arthritis?

A. Elevated ESR and RA factor positive

B. Decreased ESR and RA factor negative

C. Increased level of uric acid in blood

D. Decreased level of calcium in blood

The correct answer is A. Elevated ESR and RA factor positive.

The diagnosis of RA is based on clinical grounds but investigations are useful in confirming the diagnosis and assessing disease activity. The ESR and CRP are usually raised but normal results do not exclude the diagnosis. ACPA are positive in about 70% of cases and are highly specific for RA, occurring in many patients before clinical onset of the disease. Similarly RF is positive in about 70% of cases, many of whom also test positive for ACPA. Low titres of RF are found in about 10% of the normal population and in other diseases. 

Reference: Davidson's Principles and Practice of  Medicine, 22nd Edition, Page no 1100

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