How I Treat: An Algorithmic Approach to Crystalline Nephropathies

What is it about?

Crystalline nephropathies are an under-diagnosed cause of kidney disease. We propose a practical and easy approach to guide the diagnosis based on three steps: examination under polarized light, color of the crystals on hematoxylin and eosin and periodic acid schiff stains, and fluorescence. If there is a refringence under polarized light, the second step is to determine the color of the crystals. The color will guide the pathologist towards different categories of etiology. If none of the above methods are successful, pathologist should perform immunofluorescence as the third step: positive IF for kappa or lambda chains should lead to a search for light chain restricted dysproteinemia whereas negative IF indicates phosphocalcic or vancomycin crystals.

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