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Serum or Plasma Mass Concentration of Antithrombin III

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

This test measures the amount of antithrombin III, a natural protein in your blood that helps prevent abnormal blood clotting.

Quick summary

["Antithrombin III helps maintain healthy blood flow by regulating clotting processes."]

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

Key facts at a glance

LOINC
86098-1
Short code
S pneum Da 10A IgG Ser-mCnc
Synonyms
S pneum Da 10A IgG Ser-mCnc
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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

Why Is This Test Done?

Your doctor may order this test if you have a history of blood clots, bleeding disorders, or if you’re taking medications that affect clotting. It can also help monitor treatment for conditions like disseminated intravascular coagulation (DIC) or liver disease.

What to Expect Before the Test

No special preparation is needed unless instructed by your doctor. You may have a small needle inserted into your arm to draw blood. If you’re on blood thinners, check with your provider first.

What the Results Mean

Lower than normal levels of antithrombin III may indicate increased risk of clotting or liver problems. Higher levels may suggest certain genetic conditions or medications affecting clotting. Your doctor will interpret results in the context of your health.

Common Conditions Monitored

This test is often used to diagnose or manage conditions like hereditary antithrombin deficiency, liver disease, or to assess treatment effectiveness for bleeding disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Antithrombin III Level

Frequently asked questions

What causes low antithrombin III levels?
Low levels can result from liver disease, pregnancy, certain medications (like heparin or warfarin), or inherited genetic disorders. Lifestyle factors like smoking or obesity may also play a role.
How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab. Follow-up with your doctor to discuss findings.
Can I eat or drink before this test?
You can eat and drink normally unless your doctor specifies otherwise. Avoid alcohol before testing, as it may affect blood composition.
  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