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Galactomannan antigen (serum/plasma)

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

This test measures a specific fungal biomarker found in the blood, often used to detect infections caused by *Aspergillus* fungi.

Quick summary

["Helps identify fungal infections in the bloodstream, especially from *Aspergillus* mold."]

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

Key facts at a glance

LOINC
35671-7
Short code
Galactomannan Ag Spec-aCnc
Synonyms
Galactomannan Ag Spec-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
86038
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 Measuring?

Galactomannan is a polysaccharide (complex sugar) produced by certain types of fungi, including *Aspergillus*. This test detects its presence in your blood, which can indicate an active infection.

Why Might You Need This Test?

Your healthcare provider may order this test if you have symptoms of a fungal infection (such as fever, cough, or breathing difficulties) or if you’re at higher risk, like having a weakened immune system or undergoing certain treatments.

How Is the Test Performed?

A blood sample is taken from a vein, usually in your arm. The sample is then analyzed using a sensitive immunoassay to detect galactomannan levels.

What Does a Positive Result Mean?

A positive result suggests a high likelihood of an *Aspergillus* fungal infection, though other fungi or conditions could also cause a false positive. Further testing or medical evaluation is needed to confirm the diagnosis.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: This test is primarily used as a screening or confirmatory tool for invasive aspergillosis (a serious lung or blood infection) in high-risk patients, such as those with cancer, organ transplants, or severe immune suppression. It’s not a standalone diagnostic test but often used alongside clinical findings and imaging.

Short name

Galactomannan

Frequently asked questions

How soon can I expect results?
Results are typically available within 24 to 48 hours, depending on lab processing times. Your healthcare provider will discuss the results with you during your follow-up visit.
What are the common causes of a positive result?
A positive test result is most commonly linked to *Aspergillus* infections, but other fungi or rare conditions may also produce false positives. Your doctor will assess symptoms and medical history to determine the cause.
Can I take anything to prepare for this test?
No special preparation is needed. You may eat and drink normally before the test, but let your healthcare provider know about any medications you’re taking, as some may affect results.
  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