Adamts13 Activity

Optimal result: 0.68 – 1.63 IU/ml

By Healthmatters Editorial Team

Peer-reviewed sources

Higher or normal ADAMTS13 activity generally indicates that the enzyme responsible for regulating von Willebrand factor is functioning properly. Normal levels help prevent excessive platelet aggregation and uncontrolled clot formation in small blood vessels.

In patients being evaluated for suspected thrombotic thrombocytopenic purpura, normal ADAMTS13 activity makes TTP unlikely, helping physicians look for other causes of symptoms such as thrombocytopenia or hemolytic anemia.

Maintaining healthy vascular and liver function supports normal ADAMTS13 activity, although significant abnormalities are typically related to underlying medical conditions rather than lifestyle factors.

Low ADAMTS13 activity may indicate impaired regulation of blood clotting. Severe deficiency is strongly associated with thrombotic thrombocytopenic purpura (TTP), a rare disorder that causes widespread microvascular blood clots and low platelet counts.

Moderately reduced levels may also be seen in severe infections, liver disease, pregnancy complications, or inflammatory states. Interpretation should always be considered alongside other laboratory findings and clinical symptoms.

ADAMTS13 Activity measures the function of an enzyme that helps regulate blood clotting by breaking down large von Willebrand factor (vWF) molecules in the bloodstream. This process prevents excessive platelet clumping and abnormal clot formation in small blood vessels. Testing ADAMTS13 activity is most commonly used to diagnose thrombotic thrombocytopenic purpura (TTP), a rare but serious blood disorder that causes widespread microscopic blood clots. Low ADAMTS13 activity may indicate impaired regulation of clotting and can lead to platelet consumption, anemia, and organ damage.

ADAMTS13 (A Disintegrin And Metalloproteinase with Thrombospondin Type 1 motif, member 13) is an enzyme produced primarily in the liver that plays a critical role in the body’s hemostatic system, which regulates blood clot formation.

Its main function is to cleave ultra-large von Willebrand factor (vWF) multimers, large proteins released by blood vessel lining cells that help platelets stick together during clot formation. Without adequate ADAMTS13 activity, these large vWF molecules remain intact and can cause platelets to aggregate excessively, leading to microvascular blood clots.

The ADAMTS13 activity test measures how well this enzyme is functioning in the bloodstream.

This test is most commonly used to diagnose thrombotic thrombocytopenic purpura (TTP), a life-threatening condition characterized by:

Low platelet count (thrombocytopenia)
Destruction of red blood cells (hemolytic anemia)
Small blood clots throughout the body
Organ damage, particularly in the brain and kidneys

When ADAMTS13 activity falls below about 10% of normal, it strongly suggests TTP. The condition may be caused by inherited genetic mutations affecting ADAMTS13 or by autoantibodies that inhibit the enzyme, which is the more common acquired form.

Beyond TTP, reduced ADAMTS13 activity may also occur in other conditions, including:

Severe infections or sepsis
Liver disease
Pregnancy complications such as preeclampsia
Systemic inflammation
Disseminated intravascular coagulation (DIC)

However, mild or moderate reductions in ADAMTS13 activity are not always diagnostic of disease and must be interpreted alongside other laboratory findings.

Because ADAMTS13 activity is closely related to platelet function and clotting regulation, physicians often evaluate it together with additional blood markers such as platelet count, lactate dehydrogenase (LDH), haptoglobin, and von Willebrand factor.

Related biomarkers

ADAMTS13 Activity is often interpreted together with:

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Written by Healthmatters Editorial Team

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