Quantitative alpha-defensin testing: Is synovial fluid dilution important?

Table 1 Demographics and laboratory results of the included patients

	Total	Aseptic cases	Infected cases
Sex
Male	9	4	5
Female	31	19	12
Age (range)	67.57 (47-85)	67.65 (47-85)	67.47 (51-84)
Laterality
Right knee	21	13	8
Left knee	19	10	9
Inflammatory disease
RA	8	5	3
Gout	2	0	2
Major Criteria
Sinus Tract	4	0	4
2 positive cultures	2	0	2
Minor criteria
CRP and ESR +	9	0	9
WBC count	15	1	14
PMN%	14	0	14
Hystological +	5	0	5
1 culture	12	1	11

RA: Rheumatoid arthritis; CRP: C-reactive protein; ESR: Erythrocyte sedimentation rate; WBC: White blood cells; PMN: Polymorphonuclear neutrophils.

Table 2 Mean and range in mg/L of the initial 10 cases (5 from infected and 5 from aseptic group) in several dilutions

	Dil. 1:10, mean (range)	Dil. 1:100, mean (range)	Dil. 1:500, mean (range)	Dil. 1:1000, mean (range)	Dil. 1:5000, mean (range)
Infected cases	0.04 (0.03-0.05)	0.52 (0.40-0.76)	2.92 (1.68-4.45)	6.68 (3.62-9.62)	32.67 (12.65-50.18)
Aseptic cases	0.01 (0-0.03)	0.09 (0.02-0.30)	0.21 (0.12-0.55)	0.3 (0.24-0.48)	1.43 (1.4-1.49)
P	0.016	0.008	0.008	0.008	0.008

Mann-Whitney test.

Table 3 Mean and range of synovial fluid alpha-defensin values (in mg/dL) of all patients

	Number of cases	Dilution of 1:1000	Dilution of 1:5000
Infected cases	17 (42.5%)	6.60 (0.26-9.62)	24.10 (5.72-50.18)
Aseptic cases	23 (57.5%)	0.74 (0.24-8.54)	1.50 (1.22-4.66)
P		< 0.001	< 0.001

Mann-Whitney test.