Which synovial fluid leukocyte count range is typical for inflammatory arthritis such as rheumatoid arthritis or gout?

• A. <2000
• B. 50-100,000
• C. 2-75,000
• D. 100,000-200,000

Answer: (C)

Inflammatory arthritis causes an influx of inflammatory cells into the joint, so the synovial fluid leukocyte count rises from normal levels. In these conditions, the count is typically in the thousands up to several tens of thousands, commonly around 2,000 to 75,000 per microliter. This range captures what you’d expect with rheumatoid arthritis and crystal-induced arthritis like gout, where cells are elevated but not always as high as in septic arthritis. Counts below about 2,000 suggest a noninflammatory effusion, while very high counts (often well over 100,000) are more suggestive of septic arthritis, though there can be overlap. Therefore, the range 2,000 to 75,000 is the best fit for inflammatory arthritis.