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High-Molecular-Weight Kininogen (HMWK) in Serum or Plasma

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

This test measures the level of high-molecular-weight kininogen, a protein involved in blood clotting and inflammation processes.

Quick summary

["Your HMWK level helps assess blood clotting function and potential inflammatory responses."]

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

Key facts at a glance

LOINC
3278-9
Short code
HMWK Act/Nor PPP IA
Synonyms
HMWK Act/Nor PPP IA
Category
chemistry
Sample
plasma
Container
Lavender-top (EDTA) or Green-top (Heparin)
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

What Is High-Molecular-Weight Kininogen?

High-molecular-weight kininogen (HMWK) is a protein found in blood plasma that plays a role in the activation of the contact system, which helps regulate blood clotting and inflammation. Low levels may suggest abnormalities in clotting pathways or conditions affecting protein synthesis.

Why Might This Test Be Ordered?

Doctors may order this test to evaluate blood clotting disorders, such as hereditary angioedema, or to investigate unexplained inflammation or bleeding tendencies. It can also be part of broader assessments for conditions affecting protein function in the blood.

Sample Collection and Preparation

This test requires a blood sample drawn from a vein. The blood is typically processed into either serum (after clotting) or plasma (using an anticoagulant). The sample is then analyzed in a laboratory using immunoassay methods to detect HMWK levels.

What Does a Result Mean?

Results are reported as a concentration of HMWK in the blood. While specific reference ranges vary by lab, lower-than-normal levels may indicate hereditary conditions affecting clotting or protein metabolism, while higher levels may be less commonly associated with specific clinical concerns unless part of a broader evaluation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

HMWK Test

Frequently asked questions

What could cause abnormal HMWK levels?
Low levels of HMWK are strongly linked to hereditary angioedema, a rare genetic disorder causing swelling due to dysfunction in the contact system proteins. Other conditions that may affect HMWK include severe liver disease (since the liver produces proteins) or certain inflammatory states. Elevated levels are less frequently associated with clinical significance unless part of a diagnostic workup for unexplained findings.
How often should I get this test?
This test is usually ordered as part of a specific clinical evaluation, such as diagnosing hereditary angioedema or monitoring conditions affecting protein synthesis. Your doctor will determine the need for repeat testing based on your symptoms and medical history.
Can diet or lifestyle affect HMWK levels?
Dietary factors or lifestyle choices typically do not directly influence HMWK levels, as this protein is primarily produced by the liver and regulated by genetic and inflammatory processes. However, managing chronic conditions like liver disease or inflammatory disorders may indirectly impact protein metabolism.
  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