Source and Significance of Raised and Synovial fluid Enzymes in Rheumatoid Arthritis Serum

Fifty four patients with RA were included in the study. Blood samples were obtained from all cases and synovial fluid (SF) samples were obtained from 24 patients presenting with knee effusion. Besides routine tests of rheumatoid activity ESR, CRP, the following enzymes were analysed in serum and SF samples: alkaline phosphatase (ALP), LDH, 5’ nucleotidase (5’ NT) and adenosine deaminase (ADA), quantitative determination of LDH isoenzymes and qualitative determination of ALP isoenzymes. Cytological examination of SF was also carried out. Results revealed elevated serum levels of ALP, LDH, 5’ NT & ADA in 81 %, 27.77%, 23.8% and 50% of cases respectively. Significantly higher SF levels were found for LDH, 5’NT & ADA when compared to serum levels. The values were 240.5 _s 149.6 U/l, 10. 72 s 9.05 U/l. 52.79 s_ 27.78 U/l for SF and 182.75 * 97.46 ? 3.57 and 23.6 2 12.36 for serum enzymes respectively. SF serum ratio demonstrated a value less than one for ALP but greater than one for LDH, 5’NT & ADA, this signifies that ALP originates mainly from the liver and passes to joint tluid due to increased permeability of synovial membrane, while the other three enzymes most probably originate from the joint itself and diffuse to blood stream. Serum LDH isoenzyme pattern was predominantly of LD, and LD1 25.1 f 5.44% and 33.42 k 8.72% respectively while SF LDH lsoenzyme pattern was predominantly of LD4 and LDg 20.95 20.95 * 5.25 and 35.57 + 5.78 respectively. This shift of LDH isoenzyme pattern towards the slowly migrating form is probably due to increased demands of the highly cellular SF in RA for anaerobic glycolysis to supply its energy requirements. Serum LDH was significantly elevated in active RA than inactive cases, values being 311.85 * 97.86 and 208.12 f 104.53 respectively. A positive correlation was found between SF LDH and PMN cell count indicating the value of LDH as a marker of disease activity better than ESR.