title: Laboratory evaluation of hypercoagulable states in patients with central retinal vein occlusion who are less than 56 years of age.
abstract: OBJECTIVE
  To investigate whether hypercoagulability plays a role in thrombus formation in patients with central retinal vein occlusion (CRVO) who are less than 56 years of age.
  
  
  METHODS
  Prospective, observational case series with retrospective comparative controls.
  
  
  METHODS
  Participants included 55 consecutive patients with CRVO less than 56 years of age. The laboratory's age-matched control groups were used to compare results for the same tests.
  
  
  METHODS
  Fifty-five patients with CRVO less than 56 years old (mean age, 44 years) underwent laboratory evaluation for homocysteine, activated protein C resistance, protein C activity, protein S activity, antithrombin III activity, antiphospholipid antibodies, and anticardiolipin antibodies. The results were compared with previously drawn age-matched control groups obtained by the same laboratory for statistical significance.
  
  
  METHODS
  Patients were considered to have a positive test if their results were outside the laboratory's established range.
  
  
  RESULTS
  Fifteen of 55 patients (27%) had one positive test result suggesting hypercoagulability. Compared with the control groups, these patients less than 56 years old with CRVO had a higher incidence of coagulation abnormalities by laboratory testing. Among the parameters tested, hyperhomocysteinemia and circulating antiphospholipid antibodies were significantly more common in the CRVO patients (P < 0.05) compared with age-matched controls.
  
  
  CONCLUSIONS
  Hypercoagulability may play a role in the pathogenesis of CRVO in patients less than 56 years old. The cause of CRVO remains multifactorial, and laboratory tests suggesting hypercoagulable states alone cannot account for the cause in most of these patients less than 56 years of age. The authors recommend examining blood pressure, intraocular pressure, complete blood count, glucose levels, and a lipid panel on all patients with CRVO. When tests for these common risk factors for CRVO are negative, consider ordering selected tests in young patients with CRVO to rule out thrombophilias, especially in patients with bilateral CRVO, a history of previous thrombosis, or family history of thrombosis.
authors.affiliation: Retina Unit, Department of Ophthalmology, Kaiser Permanente Medical Center, 27400 Hesperian Boulevard, Hayward, CA 94545-4299, USA. Mike.Lahey@kp.org
authors.forename: J Michael
authors.initials: JM
authors.lastname: Lahey
authors.forename: Murat
authors.initials: M
authors.lastname: Tunç
authors.forename: John
authors.initials: J
authors.lastname: Kearney
authors.forename: Barbara
authors.initials: B
authors.lastname: Modlinski
authors.forename: Howard
authors.initials: H
authors.lastname: Koo
authors.forename: Robert N
authors.initials: RN
authors.lastname: Johnson
authors.forename: Stephen
authors.initials: S
authors.lastname: Tanaka
mesh_terms: D020016:Activated Protein C Resistance / Q000378:metabolism; D000328:Adult; D001772:Blood Cell Count; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure; D005165:Factor V; D005260:Female; D006710:Homocysteine / Q000097:blood; D006801:Humans; D007429:Intraocular Pressure; D008055:Lipids / Q000097:blood; D016682:Lupus Coagulation Inhibitor / Q000097:blood; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011486:Protein C / Q000032:analysis; D017293:Protein S / Q000032:analysis; D012170:Retinal Vein Occlusion / Q000097:blood* / Q000209:etiology; D012189:Retrospective Studies; D019851:Thrombophilia / Q000150:complications / Q000378:metabolism*
chemical_list: D001786:Blood Glucose; D008055:Lipids; D016682:Lupus Coagulation Inhibitor; D011486:Protein C; D017293:Protein S; C095381:factor V Leiden; D006710:Homocysteine; D005165:Factor V