A detailed thrombophilia work-up of the patient demonstrated persistently elevated PAI-1 activity levels, with an elevated PAI-1 antigen concentration and homozygosity for the PAI-1 4G allele (4G/4G genotype). She was treated with indefinite warfarin anticoagulation due to the unprovoked nature of her thrombotic event. A follow-up brain MRI and angiogram performed in January 2015 showed patent cerebral venous sinuses and normal venous drainage. However, the patient was left with permanent vision loss in her left eye and only partial visual acuity in her right eye. Her most recent ophthalmology examination in January 2016 showed no new optic disc edema but did show optic neuropathy and visual loss bilaterally. She remains neurologically stable on warfarin anticoagulation.
Disturbances in the fibrinolytic system, particularly in PAI-1, have been related to an increased risk of arterial and venous thrombosis. There also appears to be a relationship between PAI-1 levels and obesity, the metabolic syndrome, and insulin resistance. Although the evidence for a link between the 4G/4G genotype and cerebral sinus thrombosis is weak, we were unable to find any other inherited or acquired cause of the thrombotic event that our patient experienced. PAI-1 gene analysis and PAI-1 activity tests are not considered to be standard tests for evaluation of patients with thrombosis. However, in young patients with an otherwise unexplained thrombotic event, additional investigation, including evaluation of the fibrinolytic system, should be considered.
BMI, body mass index, ED, emergency department; CNS, central nervous system; DVT, deep venous thrombosis; MRI, magnetic resonance imaging; APTT, activated partial thromboplastin time; GPI, glycosylphosphatidylinositol; FLAER, fluorescent aerolysin; PAI, plasminogen activator inhibitor; JAK2, Janus kinase 2; tPA, tissue plasminogen activator; uPA, urokinase plasminogen activator; FXIII:A, Factor XIII A; TAFI, thrombinactivatable fibrinolysis inhibitor; mRNA, messenger RNA; FVL, Factor V Leiden; CT, computed tomography; NA, nonapplicable; RBCs, red blood cells; WBCs, white blood cells; CSF, cerebrospinal fluid; PT, prothrombin time; INR, international normalized ratio; NA, nonapplicable; APTT, activated partial thromboplastin time; TT, thrombin time; dRVV, dilute Russell viper venom; TTI, tissue thromboplastin inhibition; Ig, immunoglobulin; SGU, standard IGM beta-2 glycoprotein unit; SMU, standard IgM beta-2 glycoprotein unit; SAU, standard IgA beta-2 glycoprotein unit; MPL, IgM phospholipid units; GPL, IgG phospholipid units; APC, activated protein C
Lab Med. 2016;47(3):223-240. © 2016 American Society for Clinical Pathology