Synovial fluid leukocyte count thresholds are used to classify arthritis. Which value indicates non-inflammatory arthritis?

• A. >50,000
• B. 2000-50,000
• C. 50-100,000
• D. <2000

Answer: (D)

In synovial fluid analysis, the leukocyte count helps distinguish noninflammatory from inflammatory and septic arthritis. Noninflammatory conditions, such as osteoarthritis, typically have a low WBC count in the joint fluid, usually under about 2,000 cells per microliter. Inflammatory arthritis—such as rheumatoid or crystal-associated arthritis without infection—often shows counts from roughly 2,000 up to 50,000 cells/µL, often with neutrophil predominance. Septic arthritis tends to push the count much higher, frequently above 50,000 cells/µL, also with a neutrophil predominance.

So the value that indicates noninflammatory arthritis is less than 2,000 cells per microliter.