Here is our procedure. We think it is a very simple way to do it. 

EISENHOWER MEMORIAL HOSPITAL                    Rancho Mirage, California
	

DEPARTMENT:  ANATOMIC PATHOLOGY		       Orig. 6/93, Rev. 2/98
 
Page 1 of 2
TITLE:  URATE CRYSTALS--GOMORI'S METHENAMINE SILVER
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PURPOSE:  To demonstrate urate crystals in tissue sections.

PRINCIPLE:  Urates are stained black by this method, presumably by reacting
with the silver, which is then reduced to its metallic form.

SPECIMEN REQUIRED:  Cut 4-5 micron paraffin sections.

TECHNIQUE:  

1. 	Fixation must be in absolute alcohol at refrigerator temperature for
overnight.  Always change the 	100% alcohol at least once during this
period.

2. 	From absolute alcohol, transfer sections to Processor #1, Emergency
Run, stepping to the first 	xylene. For productivity reasons and to be
sure the machine is available for daily rushes, this is best 	done as soon
as the processor has completed the flush after its overnight run.

3.  	Embed in paraffin, and cut sections at 4 to 5 m.  Pick sections up
quickly from water bath.  Dry in the 	IA oven for 1 hour.

REAGENTS:  

	CHECK MSDS SHEETS FOR FIRST AID, SPILL AND INCOMPATIBILITY
INSTRUCTIONS  AND  NOTE  HMIG SAFETY AND WARNING INFORMATION ON 	THE
CONTAINER FOR ALL CHEMICALS.


Methenamine Silver Working Solution

	Stock Methenamine Silver
25 mL
	(See GMS procedure for preparation of stock solution)

	Distilled water
25 mL

	5% Sodium Borate
3 mL

0.1% Gold Chloride, purchased from Rowley Biochemical

3% Sodium Thiosulfate 

Light Green working solution (0.2%), purchased from Rowley Biochemical

	PLEASE NOTE SAFETY INFORMATION FOR THESE CHEMICALS:

		Silver Nitrate: Danger! May be fatal if swallowed. Harmful
if inhaled. Corrosive. Causes severe burns. Do not get into eyes, on skin,
or on clothing. Avoid breathing dust. Keep container closed. Use with
adequate ventilation. Wash thoroughly after handling. This substance is
classified as a POISON under the Federal Caustic Poison Act.

		Sodium Borate: Warning! Harmful if swallowed, inhaled or
absorbed through the skin. May cause irritation to skin, eyes and
respiratory tract. Avoid contact with eyes, skin and clothing. Avoid
breathing dust. Keep container closed. Use with adequate ventilation. Wash
thoroughly after handling. 

		Methenamine: Warning! Causes irritation. Harmful if
swallowed. Do not get into eyes, on skin or on clothing. Avoid breathing
dust. Keep container closed. Use with adequate ventilation. Wash thoroughly
after handling.








	

QUALITY CONTROL:

A section known to contain urates must be used.

Vol 4 Sec 7

A:URATES

PROCEDURE: 

1.  Deparaffinize to absolute alcohol  & rinse slides with 3 changes of
absolute alcohol.
2.  Put slides into preheated working solution of methenamine silver.
3.  Incubate for 30 minutes at 60 C.  Urate crystals should be black.
4.  Rinse sections in distilled water.
5.  Tone with gold chloride for 5 minutes.
6.  Give sections 4 or 5 rinses of distilled water.
7.  3% sodium thiosulfate for 5 minutes.
8.  Wash in tap water for 5 minutes.
9.  Rinse in distilled water.
10. Counterstain briefly in light green working solution.
11. Dehydrate, clear and mount.

RESULTS: 

Urate crystals               Black
Background                  Green

PROCEDURE NOTES:
  
1. 	Absolute Alcohol must be used as the fixative when urate crystals
are to be demonstrated.

2. 	Remember to not hydrate sections to water!

REFERENCE:  

"THEORY AND PRACTICE OF HISTOTECHNOLOGY", Second Edition, Dezna C. Sheehan,
HT (ASCP), and Barbara B. Hrapchak, M.Sc., M.T.













Vol 4 Sec 7
Revised 2/98
A:URATES
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