Urates / uric acid

Reviewer: Nat Pernick, M.D. (see Reviewers page)
Revised: 2 November 2015, last major update June 2005
Copyright: (c) 2003-2015,, Inc.
Definition / General
  • Uric acid crystals seen in acid urine
  • Urates present in tissue as sodium urate, but soluble in aqueous solutions and slightly soluble in weak alcoholic solutions, so tissue must be fixed in 95%/100% alcohol to prevent leaching of urates
  • Urates are stained black by GMS
  • Sodium urate crystals are birefringent on polarization
Micro Images

Uric acid crystals, polarized, with red plate