SERUM BIOCHEMISTRY IN RHEUMATOID ARTHRITIS, SERONEGATIVE ARTHROPATHIES, OSTEOARTHRITIS, SLE AND NORMAL SUBJECTS

Most arthritic conditions are characterized by chronic inflammation,resulting in secondary changes in serum biochemistry. In anattempt to profile different mechanisms of inflammation whichmight account for the clinical diversity of rheumatic diseases,we have measured C-reactive protein (CRP), plasma viscosity,serum histidine and total serum sulphydryl in 259 patients withrheumatoid arthritis (RA), 84 with ankylosing spondylitis (AS),76 with osteoarthritis, 69 with psoriatic arthritis, 34 withsystemic lupus erythematosus (SLE), 36 with Reiter's syndromeand 121 normal controls. The most extreme abnormalities were seen in rheumatoid arthritisand the least in osteoarthritis. The seronegative spondarthritidesand SLE occupied a midway position, emphasizing a correlationbetween biochemical abnormality and severity of inflammation. A low serum histidine characterized both RA and SLE. The formerwas more likely to be associated with a raised CRP. Plasma viscositywas characteristically raised in psoriatic arthritis and CRPin AS. KEY WORDS: Serum biochemistry, Rheumatoid arthritis, Seronegative arthropathies