Yeast and Pseudohyphae, Skin Scraping — Potassium Hydroxide Preparation, Qualitative
A microscopic examination of skin scrapings that looks for yeast and pseudohyphae, which may indicate a fungal skin infection.
["This test helps determine whether a skin lesion may be caused by a fungal infection."]
Key facts at a glance
- LOINC
- 55311-5
- Short code
- Yeast pseudohyphae Skin Ql KOH Prep
- Synonyms
- Yeast pseudohyphae Skin Ql KOH Prep
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 10
- Ref high
- 40
- Critical range
- — – 500 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- koh-preparation
- CPT
- 84484
- SNOMED
- 302774002
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What is this test?
This is a qualitative laboratory examination of material scraped from the skin. Potassium hydroxide (KOH) preparation is used to examine the sample under a microscope for yeast, pseudohyphae, and other fungal elements.
Why might I need this test?
A clinician may order this test when a rash, scaling, redness, or other skin lesion could be related to a fungal infection. It may be considered along with symptoms and physical examination findings.
How is the test performed?
The clinician collects a small sample from the affected skin, often from the edge or surface of a lesion. The material is mixed with KOH, which helps clear skin cells so that any yeast or fungal structures can be viewed under a microscope.
How do I prepare for the test?
No special preparation is usually required. Tell the clinician about medicines or topical products used on the area, because some can affect the sample or the likelihood of detecting fungal elements.
Reference range
Adult: 10-40 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Finding yeast or pseudohyphae may support a diagnosis of a superficial fungal infection, particularly when the organism is consistent with the appearance of the affected skin. A positive result does not always identify the exact cause by itself, and results should be interpreted with symptoms and examination findings. If no fungal elements are seen, infection may still be possible and additional testing may be needed.
Short name
KOH skin scraping for yeast
Frequently asked questions
Does a positive result mean I have a fungal infection?
Is this the same as a skin culture?
What if no yeast or pseudohyphae are found?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy