Topic Completed: 1 October 2013

Revised: 4 March 2019

Copyright: 2003-2015,, Inc.

PubMed Search: von Kossa methodAlizarin red SAzan stain

Nat Pernick, M.D.
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Cite this page: Pernick N. Calcium. website. Accessed November 21st, 2019.
Definition / general
  • With routine staining, calcium forms a blue-black lake with hematoxylin, usually with sharp edges
  • von Kossa method: silver is substituted for calcium in calcium salts; light or a photographic developer turns the silver black; only stains calcium bound to an anion such as phosphate or carbonate; most useful when large amounts of phosphates and carbonates are present, as with bone
  • Alizarin red S forms an orange-red lake with calcium at a pH of 4.2; works best with small amounts of calcium such as in Michaelis-Gutman bodies; this method is used on Dupont ACA analyzer to measure serum calcium photometrically
  • Azan stain used to distinguish osteoid from mineralized bone.
Microscopic (histologic) images

Malakoplakia of bladder
(von Kossa calcium stain)

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