D-LACTIC ACID IN SYNOVIAL-FLUID - A RAPID DIAGNOSTIC-TEST FOR BACTERIAL SYNOVITIS

Objective. To analyze the usefulness of D-lactic acid levels in synovi al fluid (SF) as a rapid test to support the early diagnosis of bacter ial arthritis (BA). Methods. A simple modification of the enzyme metho d used for measuring L-lactic acid was used to analyze levels of D-lac tic acid in SF from 20 cases of BA. Results were compared with those f rom 99 noninfectious arthritis, which included 90 inflammatory SF samp les. Total white blood cell count (WBC), percentage of polymorphonucle ars (% PMN) and gram stains were also determined. Results. D-lactic ac id levels were significantly higher in BA than in noninfectious arthri tis, Using a cutoff value of 0.05 mM, 85% of the SF samples from BA ha d a positive test for D-lactic acid compared with 4% of the control gr oup. The overall sensitivity of the assay was 85 % with a specificity of 95%, showing a positive predictive value for BA of 81% and a negati ve predictive value of 97%. Conclusion. The data presented suggest tha t D-lactic acid is an accurate, easy test that can be carried out in a ny laboratory, to support the early diagnosis of BA.