Do Normal Blood Test Results Rule Out Rheumatic Diseases?

Question: Do Normal Blood Test Results Rule Out Rheumatic Diseases?

Is it possible to have rheumatoid arthritis (or other rheumatic diseases) and have blood work that is within normal range for inflammation markers? How much of the diagnosis is based on the blood tests for inflammation?

Answer: Most patients with rheumatoid arthritis (RA) have some marker of the disease in the blood. This might include:

• positive rheumatoid factor (RF)
• cyclic citrullinated peptide (CCP) antibody
• elevated measures of inflammation
• an increase erythrocyte sedimentation rate (ESR)
• C-reactive protein (CRP).

On the other hand, occasionally a patient with RA may have active disease and all these tests are normal. In general, those patients without these abnormalities in the blood are less likely to develop joint damage. Almost all patients with lupus have the presence of the antinuclear antibodies (ANA) or if negative, an SSA antibody or anti-phospholipid antibodies (associated with an increased risk of thrombosis such as a blood clot or stroke or miscarriage). Once again, there are patients, although rare, who have lupus despite these negative tests. Most Sjogren's syndrome patients will typically exhibit an elevated ESR or have a positive ANA, RF, SSA or SSB antibody in their blood.

It is important to remember that while blood tests are helpful in confirming a diagnosis and assessment of disease activity, it is more important to diagnose and treat based on the patient's clinical presentation.

_{Dr. Zashin is clinical assistant professor at University of Texas Southwestern Medical School and an attending physician at Presbyterian Hospitals of Dallas and Plano. Dr. Zashin is author of Arthritis Without Pain - The Miracle Of TNF Blockers. The book is useful for anyone on one of the biologic drugs or considering the biologic drugs.}