The effect of biological crystals and human serum on the rate of formation of crystals of monosodium urate monohydrate in vitro.

A simple, reproducible method of measuring monosodium urate monohydrate (urate) crystal formation in the presence of biological materials in vitro is described. The method allows both seeded and unseeded crystal formation to be examined. Urate seed crystals markedly promoted urate crystal growth whereas the presence of hydroxyapatite or calcium pyrophosphate dihydrate crystals had a minimal effect on crystal formation. Serum promoted urate crystal formation in a concentration-dependent fashion, the effect probably being due to enhancement of nucleation.