Factors affecting urate solubility in vitro.

Acute gouty arthritis occurs when crystals of monosodium urate form and deposit in joints and connective tissue. These crystals then provoke the characteristic acute inflammatory response of gout (Seegmiller, 1965), and may accumulate chronically forming gouty tophi. Although deposition of urate crystals from hyperuricaemic body fluids is an essential requirement in the pathogenesis of gout, only a small percentage of hyperuricaemic individuals ever shows clinical signs of gout. The factor or factors predisposing certain hyperuricaemic persons and not others to develop gout are as yet unknown. Thus, it is important for an understanding of the pathogenesis of gout to examine the factors which influence urate solubility and which may ultimately prove to be responsible for the initiation of urate crystal formation. Factors presently known to influence urate solubility include pH, temperature, ionic strength, and the binding of urate to macromolecules, such as plasma proteins and mucopolysaccharides of connective tissue. We have recently published a theoretical discussion offactors influencing urate solubility (Wilcox, Khalaf, Weinberger, Kippen, and Klinenberg, 1972). The present communication summarizes the results of laboratory studies designed to further quantify some parameters of urate solubility in buffers and biological fluids.