Measurement of plasminogen activator inhibitor-1 serves to diagnose certain genetic diseases with increased or decreased levels; in the differential diagnosis of fibrinolytic mechanism diseases; and as a prognostic factor for the occurrence or recurrence of thrombosis.
The plasminogen activator inhibitor-1 (PAI-1) is a member of a family of proteins that inhibit plasminogen activators. PAI-1 is a glycoprotein with a molecular weight of 47 kD. During fibrinolysis, tissue plasminogen activator (tPA) converts the inactive protein of plasminogen to plasmin. Plasmin, in turn, plays a critical role in fibrinolysis by degrading fibrin. Plasmin also displays localized protease activity in several other physiological functions, including ovulation, cell migration, and epithelial cell differentiation.
The plasminogen activator inhibitor-1 is the major inhibitor of tPA and other plasminogen activators in the blood. PAI-1 restricts the production of plasmin and serves to control fibrinolysis. Uncontrolled production of plasmin can lead to excessive fibrin cleavage and an increased risk of bleeding. The levels of PAI-1 are partially gene-controlled. Certain polymorphisms in the PAI-1 gene are associated with increased blood concentrations. Elevated levels of PAI-1 have been shown to be associated with an increased risk of atherosclerotic lesions. Also, insulin and proinsulin levels are correlated with PAI-1 levels. Patients with insulin resistance syndrome and diabetes tend to have elevated PAI-1 levels. Weight loss and triglyceride and cholesterol-lowering treatment also reduce PAI-1 levels. The plasminogen activator inhibitor-1 has been shown to act as a prothrombotic factor in both arterial and venous thromboembolic disease. Elevated levels of PAI-1 are associated with an increased incidence of acute coronary syndrome, with chronic and acute coronary artery disease (CAD), and in patients suffering from restenosis after coronary angioplasty. It has also been shown that increased levels of PAI-1 may decrease the efficacy of antithrombotic therapy.
The plasminogen activator inhibitor-1 is an acute-phase protein and may increase transiently due to infection, inflammation, or trauma. PAI-1 levels increase during pregnancy.
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
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