KOH (Potassium Hydroxide) Test for Thrush
The KOH preparation test is used to
find out whether oral candidiasis (thrush) is
present in a person's mouth. A sample of skin is taken from the person's mouth
by lightly scraping the white patches.
The sample is then placed
on a slide with potassium hydroxide (KOH) solution and gently heated. This
solution slowly dissolves the skin cells but not the yeast cells. The yeast
cells can then be seen with a microscope. Color stains may be used so that the
yeast cells are easier to see.
Why It Is Done
If a person has white patches in the
mouth or on the tongue, a KOH test may be done to find out whether the person
Findings of a KOH test may include the
No yeast or other fungi are present in the sample from the
Yeast or other fungi are present in the sample from the
What To Think About
In general, a KOH test is not
needed to diagnose thrush. A doctor usually can diagnose thrush by looking at
the white patches in a person's mouth.
Complete the medical test information form (PDF)(What is a PDF document?) to help you prepare for this test.
Primary Medical Reviewer
||John Pope, MD - Pediatrics
Specialist Medical Reviewer
||Thomas Emmett Francoeur, MD, MDCM, CSPQ, FRCPC - Pediatrics
Current as of
||June 18, 2013