Test Catalog

Interpretive Handbook

Test 8973 :
Congo Red Stain

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Congo red may selectively bind to amyloid.


Abnormal deposition of amyloid in various organs may cause dysfunction of the organs.


Congo red stain is helpful in the identification of abnormal amyloid deposition in clinical specimens.

Useful For Suggests clinical disorders or settings where the test may be helpful

Demonstration of amyoid deposits in tissues, body fluids, or subcutaneous fat aspirations. Aids in the diagnosis of all forms of amyloidosis.

Interpretation Provides information to assist in interpretation of the test results

Positive staining is indicated by apple-green birefringence utilizing a polarized microscope.


The laboratory will provide an interpretive report.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Interpretation of stain will be contingent on fixation techniques of tissue.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretive report will be provided.

Clinical References Provides recommendations for further in-depth reading of a clinical nature

Puchtler H, Sweat F, Levine M: On the binding of Congo red by amyloid. J Histochem Cytochem 10:355-363, 1962