Hyaluronate in normal human synovial fluid.

Studies on hyaluronate in normal human synovial fluid have been hindered by the high viscosity and small volume of fluid available. Reports on hyaluronate levels in normal synovial fluid, in which a number of different methods have been used, have shown discordant results (1-4). Several methods were used in the present study to determine the hyaluronate content of normal synovial fluid. Weighing rather than pipetting the small samples of viscous fluid made it possible to measure hyaluronate in 0.25 Gm. of synovial fluid. Hyaluronate was precipitated in mucin clots formed by adding acid or a polyvalent cation to synovial fluid, and was measured indirectly by determining hexosamine in these clots. Since a part of the hexosamine of synovial fluid is not a component of hyaluronate, an important aspect of this work was the demonstration that no nonhyaluronate hexosamine was precipitated in mucin clots, and that no hyaluronate hexosamine remained in the supernatant after a mucin clot was formed. Hyaluronate content of synovial fluid was also measured by determining the fall in hexosamine after hyaluronidase digestion and dialysis of whole synovial fluid. Figures for hyaluronate in synovial fluid as determined by mucin clot technique, and by hyaluronidase digestion and dialysis of synovial fluid agreed, lending confidence in the validity of these methods.