Just for curiosity sake, what methods have been done prior to taking the
sample that lead you to believe the ion is calcium?  If suspected and
because of the solubility of urates in water, I would fix in absolute EtOH
and prevent contact with anything aqeous. Since a method like Alizarin red
for calcium is sensitive enough to demonstrate calcium in small areas of
dystrophic calcification, and since it appears that you are interested in
identifying the ion complexed to the urate, I would use that stain for
identification. If the specimen you are working with is a soft tissue, I
would question the need for decalcification/demineralization of a sample
that was suspect for urate crystals.  A few years ago we worked with a
uricase knockout model in the mouse and the kidneys had a marked amount of
crystals even at the gross level. The tissue was a bit more difficult to
section, but I believe that was due to the absolute alcohol fixation rather
than any effect from the crystal content. We used the Gomori stain for
urates, but other approaches such as the De Galantha are certainly
reasonable for this application.

rob

-----Original Message-----
From: WWmn916@aol.com [mailto:WWmn916@aol.com]
Sent: Wednesday, January 17, 2001 9:54 PM
To: histonet@pathology.swmed.edu
Subject: Urate crystals


Would anyone know if calcium urate crystals can go into any graded alcohols 
for processing?  Can it be decalcified prior to processing?  Our current 
procedure is to not put anything for urate crystal staining into any graded 
alcohol....only absolute alcohol.  The question came up concerning calcium 
urates specifically.  Thanks for any help. Deb      WWmn916@aol.com