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Yeast and Pseudohyphae, Specimen — Qualitative, KOH Preparation

Published: August 9, 2026Updated: August 17, 2026

A microscopic examination of a specimen for yeast and pseudohyphae using a potassium hydroxide (KOH) preparation.

Quick summary

["This test checks a sample for yeast and pseudohyphae, which can support the presence of a fungal infection."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
55308-1
Short code
Yeast pseudohyphae Spec Ql KOH Prep
Synonyms
Yeast pseudohyphae Spec 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 test examines a specimen under a microscope to look for yeast cells and pseudohyphae. A potassium hydroxide (KOH) preparation is used to help clear away noncellular material so any fungi are easier to see.

Why might I need this test?

It may be ordered when symptoms suggest a fungal infection, such as itching, redness, discharge, or skin changes. The results can help distinguish fungal organisms from other causes of the same symptoms.

How is the test performed?

A small amount of the collected specimen is mixed with KOH solution and examined microscopically. The laboratory reports whether yeast, pseudohyphae, or both are observed.

How do I prepare for the test?

Follow the instructions provided by your healthcare professional or the laboratory. Depending on the specimen being tested, you may be asked to avoid creams, powders, or other products before collection.

Reference range

Adult: 10-40 U/LN/A

Specimen: serum

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 and pseudohyphae can support a diagnosis of a superficial fungal infection. Yeast alone may represent normal colonization or contamination, so results should be interpreted with symptoms and the specimen source.

Short name

Yeast and Pseudohyphae, KOH Prep

Frequently asked questions

What does a positive result mean?
A positive result means yeast, pseudohyphae, or both were seen in the specimen. This may indicate a fungal infection but can also reflect normal colonization, depending on the specimen and clinical findings.
Can yeast or pseudohyphae be found without an infection?
Yes. Some yeast can normally live on the skin or in mucosal areas, and pseudohyphae may occasionally be present without clear symptoms. Your clinician will interpret the finding in context.
Does this test identify the exact type of fungus?
Usually, no. A KOH preparation shows the presence of fungal elements under the microscope; additional testing may be needed to identify the specific organism.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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