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Yeast and Pseudohyphae, Sputum — KOH Preparation, Qualitative

Published: August 9, 2026Updated: August 16, 2026

A qualitative sputum test that uses a potassium hydroxide preparation to look for yeast and pseudohyphae, which may be associated with Candida.

Quick summary

["Detecting yeast or pseudohyphae in sputum can support evaluation for a Candida-related respiratory infection, but findings must be interpreted with symptoms and other test results."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
55309-9
Short code
Yeast pseudohyphae Spt Ql KOH Prep
Synonyms
Yeast pseudohyphae Spt Ql KOH Prep
Category
liver
Sample
sputum
Container
Sterile sputum container
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
koh-preparation
CPT
84484
SNOMED
302774002
Specimen volume
3-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
TAT
4–24 hours
Order
routine

What is this test?

This test examines sputum for yeast and pseudohyphae, which are fungal forms often associated with Candida. A potassium hydroxide (KOH) preparation is used to help make these organisms easier to see under a microscope.

Why might I need this test?

Your clinician may order this test when you have a persistent cough, fever, wheezing, or increased sputum and Candida-related pneumonia is suspected. It may also be used to evaluate suspected respiratory tract colonization.

How is the test performed?

A sputum sample is mixed with a KOH solution and examined microscopically. The result is reported as positive or negative if yeast or pseudohyphae are identified.

How do I prepare for the test?

Follow your clinician or laboratory's instructions for collecting sputum. A deep cough and good oral hygiene can help reduce contamination with food, toothpaste, or mouth organisms. If collection instructions are unclear, ask the testing site before providing the sample.

Reference range

Adult: 10-40 U/LN/A

Specimen: sputum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

A positive result means yeast or pseudohyphae were seen in the sputum sample. This may reflect Candida colonization or, together with compatible symptoms and other findings, a Candida-related respiratory infection. A negative result does not completely rule out fungal infection, particularly if the sample was difficult to obtain or the infection is localized.

Short name

Sputum yeast and pseudohyphae (KOH preparation)

Frequently asked questions

Does a positive result mean I definitely have a Candida infection?
No. Yeast and pseudohyphae can sometimes be present as part of normal or temporary colonization. Your clinician will interpret the result with your symptoms, medical history, and other laboratory or imaging findings.
What is a KOH preparation?
KOH is a laboratory chemical used in a microscopic preparation to help clear cellular material and make certain fungi easier to identify. It is a standard method for examining respiratory specimens for yeast and fungal structures.
How is sputum collected for this test?
You generally cough material from deep in the lungs into a sterile container, following the instructions provided by the laboratory. If you cannot produce sputum, ask your clinician whether another specimen or test should be considered.
  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 16, 2026. · Read our editorial policy