Concentration of hyaluronic acid in synovial fluid.

ISOHE (1) HAS DESCRIBED a color reaction produced by the addition of alcoholic carbazole to uronic acids previously heated in 87% sulfuric acid. The purpose of the present report is to apply a modification of this method to the determination of hyaluronic acid in synovial fluid. The concentration of mucin in synovial fluid has been determined by the turbidity of the mucin clot (2) or by the chemical estimation of the nitrogen or glucosamine content of the precipitated mucin (3). Inconstancy of the coprecipitating protein makes a direct estimate of hyaluronic acid unreliable by this method. Hyaluronic acid has been determined directly from the concentration of glucosamine in protein-free filtrates of synovial fluid (4) but has been reported on relatively few patients.