SYNOVIAL-FLUID LEUKOCYTOSIS - STUDY OF EXTREMES

Three hundred and eighty-eight synovial fluids from 310 patients with definite diagnoses were reviewed. Seventy per cent of the patients with culture-proved infections in the joint space had leukocyte counts above 50,000/mm3 whereas 12.5 per cent of the patients with gout, 10 per cent of those with pseudogout and 4 per cent of those with rheumatoid arthritis had leukocyte counts in this high range. White cell counts ranged from 6,000 to 46,000/mm3 in 30 per cent of the patients with infectious arthritis. However, their fluids contained 90 per cent neutrophils and poor mucin clots, and within 12 to 48 hours repeat aspirations of the same joint showed large increases in the leukocyte count. These patients were divided into two groups, one with mild infections due to Neisseria gonorrhea and Diplococcus pneumoniae, and another consisting of patients with complicated underlying diseases whose infections, usually due to more virulent organisms, were poorly controlled and whose mortality rate was 25 per cent within days of synovial fluid analysis. In one fourth of the fluids with sodium urate crystals and one third of the fluids with calcium pyrophosphate crystals, leukocyte counts were below 2,500/mm3. Compared to patients with gouty arthritis, a larger number of patients with pseudogout had normal mucin precipitates despite higher numbers of leukocytes. These data document the magnitude of overlap at extremes of synovial fluid leukocytosis in common forms of arthritis and suggest a need for a careful search for crystals in fluids with high as well as low leukocyte counts. © 1979.