KOH Examination of Hairs, Nails and Skin Lesions

by admin on September 18, 2010

KOH (potassium hydroxide ) Test is used to detect the type of fungi which has caused infection in those skin lesions where we are not able to make diagnosis by seeing the lesions. It is also used to detect the fungal cause of hair fall by looking through which fungi is causing infection in hair roots, similar is the condition with nail infections.

KOH has the property to dissolve all tissues, but it does not dissolve fungal hyphae, so we put scraping of skin lesions, hair roots, and nail in 10% KOH solution, so that after some time tissues are dissolved and what is left is fungal hyphae, which we can see under microscopes and give appropriate antifungal tablets.

KOH dissolves skin tissue in 2-5 minutes, hairs in 30 minutes and nails in 24 hours, so this is the time for which scraping are to be kept in KOH solution.

Site of Scraping: We take scraping from periphery containing both healthy and diseased tissue in case of skin, in hairs we just pluck hairs with forceps and put hair root in KOH solution, similar with nails. Scrapings should be taken by 15 number blade fixed to scalpel.

Smartly put coverslip over slide and wait for appropriate time, after that see under light microscope to see which fungi has caused infection.

Click here to see how fungal hyphae appears under microscope.

Now watch out the video below on youtube explaining whole procedure how to make slide for KOH examination and how to take scrapings of skin, hairs and scalp by us.

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