What is the diagnostic test commonly used to identify nail fungus?

• A. KOH (potassium hydroxide) examination
• B. Biopsy of the nail
• C. Blood test for fungal markers
• D. Nail culture

Answer: (A)

The KOH (potassium hydroxide) examination is the most widely used diagnostic test to identify nail fungus. In this procedure, a sample of the nail or skin is collected and then treated with potassium hydroxide, which helps to clear away debris, allowing for the visualization of fungal elements under a microscope. This test is particularly effective because it can confirm the presence of fungal hyphae or spores directly, providing a rapid and preliminary diagnosis of a fungal infection.

While other methods, such as nail cultures, can also diagnose nail fungus by growing the fungi from a sample, they often take longer to yield results. Blood tests for fungal markers are generally not used to diagnose nail fungus specifically since they are more appropriate for systemic fungal infections. Similarly, nail biopsies can be utilized to investigate other conditions but are more invasive and not the standard initial approach for identifying nail fungal infections. Thus, the KOH examination is preferred for its speed and direct evidence of fungal infections.