Plasminogen Activator Inhibitor Type 1 (PAI-1) and Thrombophilia: A 10 Year Retrospective Review of Clinical Data at a Large Children's Hospital

Introduction: Plasminogen activator inhibitor type 1 (PAI-1) is the most important regulator of fibrinolysis. Elevated PAI-1 levels are reported to be prothrombotic and have been associated with cardiovascular disease, obesity and cancer. PAI-1 synthesis is regulated by insulin, glucocorticoids and cytokines like tumor necrosis factor-α. The single base pair guanine deletion 4G PAI-1 genetic polymorphism has been linked to elevation of PAI-1 antigen and/or activity levels. Genotype frequencies in Caucasian populations have been estimated at 0.25 (5G/5G), 0.49 (4G/5G) and 0.26 (4G/4G). Increased thrombosis risk has been reported in patients with the combination of PAI-1 4G and factor V Leiden (FVL) genetic polymorphisms. Our pediatric specialty laboratory offers PAI-1 genotyping, PAI-1 antigen and PAI-1 activity assays as part of thrombophilia testing. The laboratory at the children's hospital is also a reference lab for the community. We retrospectively reviewed the results of PAI-1 testing over the last 10 years.