What is a common laboratory finding in rheumatoid arthritis?

• A. Low levels of C-reactive protein (CRP)
• B. Positive rheumatoid factor (RF)
• C. Negative anti-nuclear antibodies (ANA)
• D. High levels of insulin

Answer: (B)

In rheumatoid arthritis (RA), a common laboratory finding is the presence of a positive rheumatoid factor (RF). RF is an autoantibody that is often found in the blood of individuals with RA, as well as in some other autoimmune conditions. Its presence is indicative of the body's immune response, which mistakenly targets its own tissues, contributing to the inflammation and joint damage characteristic of RA.

This positive RF can help confirm a diagnosis of rheumatoid arthritis, particularly when considered alongside clinical symptoms and other laboratory findings. Although not all patients with RA will test positive for RF, a significant percentage will, making it a useful marker in the clinical setting.

Other options, such as low levels of C-reactive protein (CRP), negative anti-nuclear antibodies (ANA), and high levels of insulin, do not align with typical laboratory findings in RA. CRP is usually elevated in inflammatory conditions like RA, indicating active inflammation. Negative ANA does not provide relevant information about RA, as ANA is more associated with other autoimmune diseases like lupus. High levels of insulin are not directly related to the rheumatic processes of RA.