Test Catalog

Test ID: A2PI    
Alpha-2 Plasmin Inhibitor, Plasma

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosing congenital alpha-2 plasmin inhibitor deficiencies (rare)


Providing a more complete assessment of disseminated intravascular coagulation, intravascular coagulation and fibrinolysis, or hyperfibrinolysis (primary fibrinolysis), when measured in conjunction with fibrinogen, fibrin D-dimer, fibrin degradation products, soluble fibrin monomer complex, and plasminogen


Evaluating liver disease


Evaluating the effects of fibrinolytic or antifibrinolytic therapy

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Alpha-2 plasmin inhibitor (antiplasmin) is synthesized in the liver with a biological half-life of approximately 3 days. It inactivates plasmin, the primary fibrinolytic enzyme responsible for remodeling the fibrin thrombus, and binds fibrin, together with factor XIIIa, making the clot more difficult to lyse. Absence of alpha-2 plasmin inhibitor results in uncontrolled plasmin-mediated breakdown of the fibrin clot and is associated with increased risk of bleeding.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Adults: 80-140%

Normal, full-term, and premature infants may have mildly decreased levels (> or =50%) which reach adult levels < or = 90 days postnatal.*

*See Pediatric Hemostasis References section in Coagulation Guidelines for Specimen Handling and Processing in Special Instructions.

Interpretation Provides information to assist in interpretation of the test results

Patients with congenital homozygous deficiency (with levels of <10%) are clinically affected (bleeding). Heterozygotes having levels of 30% to 60% of mean normal activity are usually asymptomatic.


Lower than normal levels may be suggestive of consumption due to activation of plasminogen and its inhibition by alpha-2 plasmin inhibitor.


The clinical significance of high levels of alpha-2 plasmin inhibitor is unknown.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Alpha-2 plasmin inhibitor results are potentially affected by:

-Heparin, unfractionated or low-molecular-weight >4 U/mL

-Alpha-2-macroglobulin >7 mg/mL; potentially leading to a falsely-increased result

-Hemoglobin >200 mg/dL

-Bilirubin >20 mg/dL

-Triglycerides >1000 mg/dL

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Lijnen HR, Collen D: Congenital and acquired deficiencies of components of the fibrinolytic system and their relation to bleeding or thrombosis. Blood Coagul Fibrinolysis 1989;3:67-77

2. Francis RB Jr: Clinical disorders of fibrinolysis: A critical review. Blut 1989;59:1-14

3. Aoki N: Hemostasis associated with abnormalities of fibrinolysis. Blood Rev 1989;3:11-17

Special Instructions Library of PDFs including pertinent information and forms related to the test