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Immunoglobulin M (IgM) Measurement by Turbidimetry

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

This test measures the amount of Immunoglobulin M (IgM) in your blood. IgM is a type of antibody that helps your immune system fight infections.

Quick summary

["IgM helps your body identify and fight infections, including some viruses and bacteria."]

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

Key facts at a glance

LOINC
111447-9
Short code
IgG Msmt Ur
Synonyms
IgG Msmt Ur
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What IgM Tests Are Used For

IgM antibodies are often checked to help diagnose or monitor certain infections, such as viral hepatitis, Epstein-Barr virus (EBV), or other acute infections. It can also be used to assess immune responses to vaccines or chronic conditions like certain autoimmune diseases.

How the Test Works

This test uses a method called turbidimetry to measure IgM levels. A small sample of your blood is mixed with a reagent that reacts with IgM. The amount of light blocked by the reaction helps determine the IgM concentration in your blood.

When You Might Need This Test

Your healthcare provider may order this test if you have symptoms of infection, such as fever, fatigue, or swollen lymph nodes. It can also be part of a broader evaluation for conditions like chronic infections, immune system disorders, or to check for exposure to certain pathogens.

Preparation for the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw a blood sample. If you are on blood thinners or have a history of bleeding issues, let your doctor know before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

IgM Level (Turbidimetric)

Frequently asked questions

Why is IgM important in diagnosing infections?
IgM is produced early in an infection and can indicate an acute immune response. High levels of IgM may suggest recent exposure to a virus or bacteria, such as hepatitis A or Epstein-Barr virus. However, IgM alone is not always definitive and is often used alongside other tests or clinical findings.
Can IgM levels help determine the cause of chronic symptoms?
Yes, elevated IgM levels can sometimes help identify chronic infections or conditions like certain autoimmune diseases. However, results should be interpreted by a healthcare provider in the context of your symptoms and other test results.
What does it mean if my IgM levels are low?
Low IgM levels may suggest a weakened immune response, which can occur in certain immune deficiencies or advanced age. This finding should be discussed with your doctor to explore underlying causes and appropriate next steps.
  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