Articular chondrocalcinosis microanalysis of pyrophosphate (ppi) in synovial fluid and plasma

A new microassay method with precision of ±5% was developed to quantitate pyrophosphate in synovial fluid and plasma with starting volumes of 0.5 ml. A highly significant elevation of synovial fluid pyrophosphate concentration was found in some patients with osteoarthritis and gouty arthritis in addition to the well‐established elevation in synovial fluid of subjects with pseudogout. No gradient of pyrophosphate between plasma and synovial fluid of patients with rheumatoid arthritis or in normal subjects was detectable. Studies of various parameters reflecting inflammation failed to show a correlation with the concentration of pyrophosphate in patients with pseudogout.