Lab

Prothrombin Time

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Prothrombin Time, ProTime, Pro-Time, PT, International Normalized Ratio, INR

  • Precautions
  1. International Normalized Ratio (INR) and ProTime (PT) were developed only to monitor Warfarin
    1. Cirrhosis may be associated with an increased INR/PT, but may also be Hypercoagulable
  • Interpretation
  • Normal
  1. International Normalized Ratio (INR)
    1. See Warfarin
  2. ProTime (replaced by INR)
    1. Range: 10-12 sec
  • Interpretation
  • Increased
  1. Liver disease
  2. Heparin, Warfarin
  3. Clotting Factor deficiency
    1. Factor I Deficiency
    2. Factor II Deficiency
    3. Factor V Deficiency
    4. Factor VII Deficiency
    5. Factor X Deficiency
  4. Disseminated Intravascular Coagulation (DIC)
  5. Vitamin K Deficiency
  6. Afibrinogenemia
  7. Dysfibrinogenemia
  8. Medications
    1. Salicylate or Aspirin
    2. Chloral Hydrate
    3. Diphenylhydantoin
    4. Estrogens
    5. Antacids
    6. Phenylbutazone
    7. Quinidine
    8. Antibiotics
    9. Allopurinol
    10. Anabolic Steroids
  • Decreased
  1. Vitamin K supplementation
  2. Thrombophlebitis
  3. Medications
    1. Glutethimide
    2. Estrogens
    3. Griseofulvin
    4. Diphenhydramine