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Myeloperoxidase (MPO) in Blood

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

This test measures the amount of myeloperoxidase, an enzyme produced by white blood cells called neutrophils, in your blood. It may be used to assess immune function or evaluate conditions affecting these cells.

Quick summary

["MPO helps identify immune system activity and potential blood disorders."]

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

Key facts at a glance

LOINC
63397-4
Short code
Myeloperoxidase Ab Fld Ql IA
Synonyms
Myeloperoxidase Ab Fld Ql IA
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
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

Why Might This Test Be Ordered?

Your healthcare provider may order this test if you have symptoms or conditions linked to neutrophil dysfunction, such as infections, autoimmune diseases, or certain blood disorders. It could also be part of a broader evaluation for conditions like leukemia, neutropenia, or inflammatory diseases.

What Does the Test Involve?

A small blood sample will be drawn from a vein, usually in your arm. The sample is then sent to a lab for analysis. The test measures the enzyme’s presence in your bloodstream, which can reflect the activity of neutrophils or potential abnormalities in their function.

What Are Common Uses?

This test may be used to monitor immune responses, diagnose or manage conditions affecting neutrophils (e.g., infections, certain cancers), or assess the effectiveness of treatments targeting white blood cells.

What Are Possible Results?

Results are not typically provided with a specific numeric range, as interpretation depends on clinical context, symptoms, and other lab findings. Elevated levels may suggest increased neutrophil activity or certain inflammatory conditions, while very low levels could indicate immune suppression or blood disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

MPO Level

Frequently asked questions

What Does a High Level Mean?
A high myeloperoxidase level may indicate an active immune response, such as an infection, inflammation, or autoimmune condition. It could also be part of a diagnostic workup for conditions like vasculitis or certain cancers.
What Does a Low Level Mean?
Low myeloperoxidase levels may suggest neutropenia (low neutrophil count), immune suppression, or certain genetic disorders affecting white blood cell production. Always discuss results with your healthcare provider.
How Often Should This Test Be Done?
The frequency depends on your medical condition and treatment plan. Your provider will determine how often this test is needed based on your symptoms, diagnosis, and ongoing care.
  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