H-1-NUCLEAR MAGNETIC-RESONANCE STUDIES OF HUMAN SYNOVIAL-FLUID IN ARTHRITIC DISEASE STATES AS AN AID TO CONFIRMING METABOLIC-ACTIVITY IN THE SYNOVIAL CAVITY

1. A H-1-n.m.r. method was used to measure concentrations of valine, a lanine, lactate, acetate, hyaluronan and lipids in synovial fluid obta ined, during the normal course of examination, from the knee joints of patients attending rheumatology and orthopaedic clinics. Fluid was av ailable from 16 patients with osteoarthritis, 18 patients with rheumat oid arthritis, four patients with meniscal tear and one patient each w ith systemic lupus erythematosis, mono-arthritis, synovitis and loose bodies. Four normal specimens were obtained for comparison. 2. Valine, alanine and acetate levels all showed a normal Gaussian distribution, reflecting the distributions within the serum of the sample populatio n. 3. Lactate concentrations divided into two distinct patterns. At co ncentrations below 2.5 mmol/l the lactate levels showed a Gaussian dis tribution, reflecting the distribution in normal serum. The normal syn ovial fluid specimens belong to this distribution. Above 2.5-3.0 mmol/ l, lactate levels were asymmetric in distribution with a long tail at higher concentrations. These high levels of lactate can be explained b y the generation of lactate through anaerobic metabolism within the sy novial cavity. This metabolic process is triggered by a general inflam matory condition such as in rheumatoid arthritis. 4. The distribution of n.m.r.-observable lipid concentrations in rheumatoid arthritis and osteoarthritis each shows a normal distribution and the mean concentra tion is significantly higher in rheumatoid arthritis. 5. An increased n.m.r.-observable hyaluronan concentration is associated with an infla mmatory situation. 6. It is concluded that raised levels of lactate an d n.m.r.-observable hyaluronan and lipids are useful markers to aid th e clinical distinction between rheumatoid arthritis and osteoarthritis . The results of this study confirm rheumatoid arthritis as an inflamm atory disease inducing higher metabolic activity within the synovial c avity.