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Coagulation profile final by Pandian M
The document outlines the coagulation profile, detailing the factors involved in blood clotting, the sequence of clotting mechanisms, and various tests to assess bleeding disorders. It elaborates on clinical significance, methods of measuring bleeding and clotting times, and the implications of abnormal results. Key tests discussed include bleeding time, clotting time, platelet aggregation, prothrombin time, and activated partial thromboplastin time.
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Overview of coagulation profile and haemostasis. Haemostasis is the physiological process preventing bleeding. Discusses factors and mechanisms involved in blood clotting, including bleeding time (BT) and clotting time (CT). Methods like Duke and Ivy, and tests like PT & PTT are explained.
Covers tests including Capillary Fragility Test, Platelet Aggregation Test, PT, PTT, APTT, and TT for assessing bleeding disorders.
Concluding remarks on coagulation studies and references used in the presentation.
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Coagulation profile final by Pandian M
- 1. Coagulation Profile Pandian M Departmentof Physiology D. Y. Patil Medical College, Kolhapur
- 2. Slo’s • DEFINITION • FACTORSINVOLVED IN BLOOD CLOTTING • SEQUENCE OF CLOTTING MECHANISM • BLOOD CLOT • ANTICLOTTING MECHANISM IN THE BODY • ANTICOAGULANTS • PHYSICAL METHODS TO PREVENT BLOOD CLOTTING • PROCOAGULANTS • TESTS FOR BLOOD CLOTTING • APPLIED PHYSIOLOGY
- 3. Introduction • This testsare determined to assess the integrity of haemostatic mechanism. HAEMOSTASIS – Spontaneous arrest or prevention of bleeding by physiological process is called haemostasis.
- 4. Series of eventsinvolved in haemostasis
- 5. Bleeding Time • Bleedingtime is defined as time interval between puncture to the blood vessel to the stoppage of bleeding. Methods of determination of bleeding time- I) Duke Method II) Ivy Method
- 6. Duke Method [ 30sec interval ] 5 blots (4 blood blots+ 1 blank blot) x 30 sec = 2mins 30 sec
- 7.
- 8. Clotting Time • Clottingtime is defined as time interval between puncture to the blood vessel to the formation of fibrin thread. Methods of determination of clotting time- I) Capillary tube method II) Lee - White method
- 9.
- 11. Lee - Whitemethod Principle Venous blood is collected in clean glass tube without any anticoagulant. The time taken by blood to clot at 37 degree Celsius is noted as clotting time. Normal Value – 5 to 12 minutes Clinical Significance This method is more reliable than the capillary tube method. The clinical significance of this method is the same as that of capillary tube method
- 12. Conditions where BT& CT are altered Bleeding time is prolonged in : i) Thrombocytopenia - ↓ in platelet count ii) Thrombasthenia – Platelet count is normal but they are functionally abnormal iii) Von Willebrand disease – Platelet defect combined with factor VIII deficiency. iv) Purpura – It is a condition with various manifestation & different causes, characterized by capillary abnormality resulting in haemorrhages into the skin, mucous membrane, internal organ & other tissues.
- 13. Clotting time isprolonged in : i) Classical Haemophilia (Haemophilia A) ii) Vitamin K deficiency iii) Christmas disease iv) Liver diseases – Hepatitis, cirrhosis v) Anticoagulant overdose
- 14. Clinical significance ofdetermining BT & CT It is very important to know BT & CT in the following conditions : i) Before surgery ii) Before any biopsy, especially liver or bone marrow biopsy iii) Before putting any patient on anticoagulant therapy
- 15. Other tests forbleeding disorders Capillary Fragility Test Principle This test measures the ability of the capillaries to withstand increased stress. petechiae appear in the forearm of the subject when the blood pressure cuff in the arm is inflated to a maximum pressure of 100mm Hg for about 5 minutes. Clinical Significance Normally,0-10 petechiae appear. More them 10 petechiae indicates capillary weakness, thrombo-cytopenia or both.
- 16. Platelet Aggregation Test Principle Anaggregating agent is added to a suspension of platelets in plasma and the response is measured turbidometrically as a change in the transmission of light by an instrument called the aggregometer. Clinical Significance Measurement of platelet aggregation is an essential part of the investigation of any patient with suspected platelet dysfunction.
- 17. Platelet Adhesiveness Test Principle Thistest measures the ability of platelets to adhere to a glass surface. When anticoagulated blood is allowed to pass at a constant rate through a plastic tube containing glass beads, some platelets adhere to the glass beads. The percentage difference of the platelet count prior to & after passing through the glass bead column indicates the functional status of platelets. Clinical Significance The normal range is 75%-95% of platelet retention. The platelet adhesiveness test is non specific. The results are abnormal in several platelet functional disorders
- 18. Clot Retraction Time Principle Bloodclots when collected in a glass tube without any anticoagulant. The clot begins to retract (after blood has clotted) within 30 seconds, & about 50% at the end of 1 hour. At the end 18-24 hours the clot should have retracted completely. Clinical Significance Abnormal clot retraction is reported when less than 50% retraction occurs at 1 hour. Clot retraction is primarily dependent on platelet function. Hematocrit & fibrinogen level also affect it. Poor clot retractability is usually seen when platelet count is less than 1,00,000.
- 19. Clot Lysis Time Principle Theclot is lysed due to fibrinolysis, which is a natural process. Due to lysis the clot becomes fluid & red cells sink to the bottom of the test tube. Clinical Significance The lysis time for the normal clot is about 72 hours. If lysis is seen within 24 hours, fibrinolysis is considered to be abnormal.
- 20. Prothrombin Consumption Test Principle Thistest determines the amount of prothrombin present in the serum after clot formation. Clinical Significance Normally, in the coagulation process more than 95% of prothrombin is used up as it is converted to thrombin. The presence of more than 5% of prothrombin in the serum indicates a quantitative or qualitative platelet deficiency
- 21. Prothrombin Time (PT) Principle Apreparation of rabbit brain emulsion (which contains tissue thromboplastin) is added to plasma in the presence of calcium. This, in the presence of factor VII triggers stage 2 of the coagulation mechanism, & the clotting time is recorded after the addition of calcified thromboplastin to the plasma Normal Value - 12-16 seconds Clinical Significance Prolonged PT suggest the possibility of deficiency of factor II, V, VII, X.
- 22. Partial Thromboplastin Time(PTT) Principle The platelet substitute, in the form of partial thromboplastin, is prepared from rabbit brain as chloroform extract. When mixed with test plasma containing excess of calcium, it leads to clot formation. Normal Value - 60 to 80 seconds Clinical Significance PTT is prolonged when there is deficiency of one or more clotting factors XII, XI, X, IX, VIII, V, II & I.
- 23. Activated Partial ThromboplastinTime (APTT) Principle The platelet substitute, in the form of partial thromboplastin is prepared from rabbit brain. This is incubated with a contacting agent (kaolin) to provide optimal activation of the intrinsic coagulation factors. The clotting time is determined after the addition of excess of calcium. Normal Value – 25 to 40 seconds Clinical Significance APTT is prolonged in deficiencies of factor XII, XI, X, IX & VIII.
- 24. Thrombin Time (TT) Principle Thrombin(commercially available) is added to the plasma along with calcium & the clotting time is determined. Normal Value – 15-20 seconds Clinical Significance Thrombin time detects the effectiveness of the stage 3 of coagulation in which fibrinogen is converted to fibrin. A prolonged TT is considered to be due to either a decrease in fibrinogen or the presence of dysfunctional fibrinogen.
- 25. Plasma Recalcification Time(PRT) Principle When excess of calcium is added to the citrated plasma, clotting occurs. Because platelet factor III is also involved in clotting through the intrinsic pathway of coagulation, the clotting occurs in a shorter time in platelet rich plasma than in platelet poor plasma. Normal Value – Platelet rich plasma - 100 to 150 seconds Platelet poor plasma – 135 to 240 seconds Clinical Significance This is an easy screening test that detects the deficiency of the factor of the intrinsic pathway, that is, factors XII, XI, X, IX, V & II.
- 27. Referred :- • Textbook of Medical Physiology • Guyton, 13th edition, • Text book of Medical Physiology • Indu khurana, • Text book of Medical Physiology • Vander’s • Text book of Medical Physiology • Sembulingam & • LPR
- 28.