1 / 14

Prothrombin time

Dr. S. Parthasarathy MD DA DNB PhD ( physio ) Mahatma Gandhi medical college and research institute , puducherry – India . Prothrombin time. Coagulation factors. I ( fibrinogen ) Forms clot (fibrin) II ( prothrombin ) III ) Calcium phospholipid (formerly known as factor IV)

emmet
Download Presentation

Prothrombin time

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Dr. S. Parthasarathy MD DA DNBPhD (physio)Mahatma Gandhi medical college and research institute , puducherry – India Prothrombin time

  2. Coagulation factors • I (fibrinogen) Forms clot (fibrin) • II (prothrombin) • III) Calcium • phospholipid (formerly known as factor IV) • V (proaccelerin, labile factor • VIUnassigned – old name of Factor Va • VII (stable factor, proconvertin) • VIII (Antihemophilic factor A) • IX (Antihemophilic factor B or Christmas factor) • X (Stuart-Prower factor) • XI (plasma thromboplastin antecedent) • XII (Hageman factor) • XIII (fibrin-stabilizing factor) Crosslinks fibrin

  3. INITIATION OF BLOOD COAGULATION Extrinsic Pathway Intrinsic Pathway Tissue trauma Leakage of Tissue Factor Blood trauma/ contact with collagen Activation of factor XII, IX, VIII Ca+2, factor VII XXa XXa Ca+2 Ca+2 Prothrombin activator Prothrombin activator Ca+2 Prothrombin Thrombin (factor II) Prothrombin Thrombin (factor II) Thrombin converts fibrinogen to fibrin

  4. Prothrombin time tests extrinsic pathway • Performed by adding a mixture of calcium and thromboplastin to citrated plasma • As a control, a normal blood sample is tested continuously • PT ratio (PTR) = Patient’s PT Control PT

  5. Normal value • 11- 14 seconds • What is INR?

  6. Thromboplastins are extracts from brain, lung or placenta of animals • Thromboplastins from various manufacturers differ in their sensitivity to prolong PT • May result in erratic control of anticoagulant therapy

  7. INR = [PTpt] ISI [PTRef] PTpt– prothrombin time of patient PTRef– prothrombin time of normal pooled sample ISI – International Sensitivity Index

  8. ISI – International Sensitivity Index • Thromboplastin may vary. • Each manufacturer gives ISI value • With reference to international control. • If the manufacturer gives 1 , it means ,the sensitivity is same • If 2, batch is half sensitive. • Usually between 1 to 1.4

  9. Example • Patient PT = 16 sec. • Control = 12 seconds. • 16/12 = 1.33. • But if ISI is 2 • INR = (1.33)2 • = 1.768.

  10. Prothrombin time • Factor 7 • It is also prolonged in 1,2,5,10 • But not useful for factor 8 and 9

  11. importance of Prothrombin time • Liver disease • Warfarin therapy • Vit. K deficiency

  12. Factors raise INR • Chr. Alcohol • Anabolic steroids • Septran • Propranolol • Metrogyl • Fluroquinolones. • INH,omez

  13. Factors decrease INR • Barbiturates • Carbamazipine. • Griseofulvin • Sucralfate. • Rifampicin.

  14. Thank you all!!

More Related