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Immunoglobulin M (IgM), Serum/Plasma — Qualitative

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

A qualitative test that evaluates IgM in a serum or plasma sample, generally reporting whether a specific IgM finding is detected.

Quick summary

["This test checks for the presence of an IgM-related finding in your blood."]

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

Key facts at a glance

LOINC
73332-9
Short code
IMP+CS ind plt IgM SerPl Ql FC
Synonyms
IMP+CS ind plt IgM SerPl Ql FC
Category
liver
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
82784
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?

Immunoglobulin M (IgM) is an antibody made by the immune system. This qualitative laboratory test evaluates IgM-related findings in serum or plasma and usually reports detected or not detected rather than a numeric concentration.

Why might I need this test?

IgM testing may be used when a clinician is evaluating a possible infection, an immune condition, or an unusual immunoglobulin pattern. The specific purpose depends on the antigen or antibody identified in the full test name and laboratory report.

How is the test performed?

A blood sample is collected, and the serum or plasma is examined using laboratory testing methods. A qualitative result is reported as detected, positive, not detected, or negative, depending on the test.

How do I prepare for the test?

Follow the preparation instructions provided by your healthcare professional or laboratory. Fasting is not usually required for this type of blood test, but the laboratory may have specific instructions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Qualitative IgM

Frequently asked questions

Does a qualitative result show how much IgM is present?
Usually, no. A qualitative result indicates whether the specific IgM finding was detected rather than providing a numeric IgM concentration.
Is IgM always a sign of illness?
No. IgM is a normal part of the immune system, so the result is meaningful only in the context of the particular antibody, antigen, or immunoglobulin pattern being tested.
Does this test require fasting?
Fasting is generally not required, but follow any preparation instructions supplied by the laboratory.
  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