How Do Doctors Diagnose Onychomycosis? The Tests You Need to Know!
Published: Feb 12, 2024
Diagnosing onychomycosis requires specific tests to confirm the presence of fungi in the nails. Learn about the different methods available.
Contents
Initial Testing Methods
The first step in diagnosing onychomycosis often involves a potassium hydroxide (KOH) preparation test. This test is quick and relatively inexpensive, providing almost immediate results. If the KOH test is negative or inconclusive, a more sensitive histopathologic examination using a PAS stain may be performed on a nail clipping.
Advanced Diagnostic Techniques
For more precise identification, fungal cultures or polymerase chain reaction (PCR) tests can be used. These tests can specify the type of fungus causing the infection, which is vital for targeted treatment. While cultures take longer to yield results, PCR tests are rapid but can be more costly and are less widely available.

Other Testing Options
Additional tests like dermatoscopy and fluorescence microscopy can also aid in diagnosing onychomycosis. Dermatoscopy involves examining the nail under magnification, while fluorescence microscopy uses special stains to highlight fungal elements. These methods can help distinguish onychomycosis from other nail conditions.
Frequently Asked Questions
A quick test to detect fungi in nails.
Yes, it's rapid and specific.
They identify the fungus type.
Yes, it helps differentiate nail disorders.
The Bottom Line
Accurate diagnosis through these tests ensures effective treatment of onychomycosis.
References
- Lawry MA, Haneke E, Strobeck K, et al. Methods for diagnosing onychomycosis: a comparative study and review of the literature. Arch Dermatol 2000; 136:1112.
- Jung MY, Shim JH, Lee JH, et al. Comparison of diagnostic methods for onychomycosis, and proposal of a diagnostic algorithm. Clin Exp Dermatol 2015; 40:479.
This article has been reviewed for accuracy by one of the licensed medical doctors working for Doctronic. Always discuss health information with your healthcare provider.
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