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Anti-Hepatitis A Virus Immunoglobulin M (IgM) Antibody (Serum/Plasma)

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

This test detects antibodies to the Hepatitis A virus (IgM antibodies) in your blood. IgM antibodies appear shortly after infection and help identify recent exposure to the virus.

Quick summary

["Helps determine if you’ve recently been exposed to Hepatitis A virus."]

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

Key facts at a glance

LOINC
77027-1
Short code
FLUAV H3 RNA Nph Ql NAA+probe
Synonyms
FLUAV H3 RNA Nph Ql NAA+probe
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
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 Does This Test Measure?

The test looks for IgM antibodies specific to Hepatitis A virus. These antibodies are produced by your immune system in response to an active infection. IgM antibodies typically appear within weeks after exposure and can stay in your system for several months.

Why Might You Need This Test?

Your healthcare provider may order this test if you have symptoms like fever, fatigue, nausea, or jaundice, or if you’ve had recent contact with someone who has Hepatitis A. It can also be used to confirm a recent infection in people who have been vaccinated.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or vein to draw blood. If you’re nervous, let your healthcare provider know so they can help make the process more comfortable.

What to Expect After the Test

After the blood is drawn, you may feel a slight pinch or bruising at the site. Apply gentle pressure to stop any bleeding. You can return to your normal activities immediately.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Positive IgM results suggest recent Hepatitis A infection. This is important for diagnosing active infection, guiding treatment decisions, and informing public health measures like vaccination recommendations or contact tracing. IgM antibodies usually decline over time as your body produces longer-lasting IgG antibodies, which can persist for years.

Short name

IgM Anti-HAV

Frequently asked questions

What does a positive result mean?
A positive result means your body is actively fighting a Hepatitis A infection at the time of testing. This is not the same as being immune, so you should avoid sharing food, utensils, or personal items with others to prevent spreading the virus.
How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time. Your healthcare provider will discuss the results with you during your follow-up visit.
Can I get vaccinated after a positive test?
Yes, but timing matters. If you test positive for IgM, vaccination is not recommended during the acute phase of infection to avoid masking symptoms. Once symptoms resolve, vaccination can be considered to build long-term immunity.
  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