Approach to coagulation disorders ppt.pptx

Approach to coagulation disorders

1. Approach to coagulation disorders By- Dr. Sanjay Mishra

2. COAGULATION Coagulation , also known as  clotting , is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair.

3. STEPS IN BLOOD CLOTTING In general blood clotting occurs in 3 stages- 1- Formation of prothrombin activator. 2-Conversion of prothrombin into thrombin. 3-Conversion of fibrinogen into fibrin.

4. STAGE 1-Formation of Prothrombin activator Blood clotting commences with the formation of a substance called prothrombin activator, which converts prothrombin into thrombin. Its formation is initiated by substances either within the blood or outside the blood. Thus, formation of prothrombin activator occurs through 2 pathways: 1- Intrinsic pathway. 2-Extrinsic pathway.

5. INHERITED DISORDRES Haemophilia A Three categories of severity have been defined by a consensus committee on the basis of FVIII activity levels. The PTT is abnormal if the factor VIII level is <25% of normal. In case of mild Factor VIII deficiency, the abnormality of PTT can be normalized by mixing the patient’s plasma with normal plasma in a ratio of 1:1; and this test, called a mixing study.

6. Clinical manifestations of hemophilia Hemophilia can affect any organ in the body

7. Early symptoms From Childhood Blue patches and bruises on the skin. Gum bleeds Frenulum bleeds. Cuts and Wounds which Bleed a long time .

8. Von Willebrand Disease (VWF) Most common congenital bleeding disorder. Autosomal dominant inheritance. The basic defect in vWD is a deficiency or abnormality of vWF function. vWF is synthesized in endothelial cells and megakaryocytes. 3 cardinal manifestations of this bleeding disorder are mucocutaneous hemorrhage, deep-muscle bleed and prolonged bleeding time. . When vWF is inadequate, platelet plug formation is depressed and bleeding occurs in a mucosal and petechial fashion.

9. Classification of von Willebrand Disease

10. TESTS FOR ASSESSMENT Antigen level (vWF:Ag)—a quantitative measure of the vWF protein without information about its function. Activity (vWF:RCo)—a functional assay that measures platelet aggregation after addition of the activator ristocetin to the patient’s plasma. vWF:RCo/vWF:Ag ratio—the ratio between antigen and activity levels, which can help distinguish type I from type II Vwd Factor VIII levels—vWF is required to maintain FVIII in circulation. Ristocetin-induced platelet aggregation (RIPA and low-dose RIPA)—patients with type IIB vWD demonstrate enhanced platelet aggregation in response to stimulation with low- dose ristocetin. Multimer assay—vWF functions optimally as a large multimer, and electrophoresis for multimer size helps to distinguish subtypes of vWD.

11. RARE COAGULATION FACTOR DEFICIENCY FACTOR DEFICIENCY LABORATORY ABNORMALITY CLINICAL FEATURES II (Prothrombin Deficiency) PT and aPTT prolonged Epistaxis, menorrhagia, and post-traumatic bleeding are most common. V (AKA- labile factor deficiency, proaccelerin deficiency, and parahemophilia.) PT and aPTT prolonged Epistaxis, menorrhagia, and post-traumatic bleeding are most common. VII (Stable factor or Proconvertin deficiency) Most common of Rare bleeding disorders Isolated PT prolonged Only severe deficiency is associated with haemorrhagic symptoms, heterozygous carriers are asymptomatic. Bleeding into CNS is particularly common. X PT and aPTT prolonged, normal thrombin. The factor X deficiency is severe bleeding disorder presents in infancy, umblical cord bleeding, epistaxis, menorrhagia, and post-traumatic bleeding are most common. XIII Normal PT and normal aPTT Delayed bleeding ,umbilical stump bleeding, miscarriages. Intracranial hemorrhage is more prevalent in factor XIII deficiency than in other inherited bleeding disorders.

12. RARE COAGULATION FACTOR DEFICIENCY AFIBRINOGENEMIA DYSFIBRINOGENEMIA MODE OF INHERITENCE Autosomal recessive Autosomal dominant PATHOLOGY Quantitative abnormality associated with the complete absence of fibrinogen molecule. Qualitative abnormality of fibrinogen molecule CLINICAL FEATURES Prolonged umbilical stump bleeding. Approximately 40% of dysfibrinogenemic patients are asymptomatic, and 45% to 50% have a bleeding disorder. LAB VALUES Increase in PT, PTT, clotting time. The thrombin clotting time remains a sensitive screening test for dysfibrinogenemias, and the PT appears to be more sensitive than the PTT

13. ACQUIRED COAGULATION DEFICENCY DEFICIENCIES OF VITAMIN K DEPENDENT FACTORS ( VII,IX,X and protein C and S) Vitamin K deficiency bleeding (VKDB) in infancy, which was historically termed hemorrhagic disease of the newborn . Impairment of uptake of vitamin K from the intestine or of hepatic synthetic capacity predispose to VKDB. (a) Prematurity (b) Placental transfer of maternal medications. (c) Inadequate dietary intake; (d) Delayed gut colonization by bacteria; (e) various obstetric and perinatal complications; (f)Possibly maternal deficiency of vitamin K; and (g) Bowel or hepatobiliary disease .

14. Clinical Features and Lab diagnosis . Bleeding in classic VKDB is severe, with melena, large cephalohematomas, and bleeding from the umbilical stump and after circumcision. Generalized ecchymoses (often without petechiae), intracranial bleeding, and large intramuscular hemorrhages may also develop. The prothrombin time (PT), The partial thromboplastin time(PTT) is prolonged. Factors V and VIII, as well as fibrinogen, are normal. In clinical practice, the triad of a prolonged PT value, a normal fibrinogen level, and a normal platelet count defines the diagnosis.

15. LIVER DISORDERS

16. DISSEMINATED INTRAVASCULAR COAGULATION

17. LABORATORY FINDINGS Platelet count - DECREASED. PROTHROMBIN TIME – INCREASED APTT- INCREASED THROMBIN TIME- INCREASED FIBRINOGEN- DECREASED. PROTAMINE SULFATE TEST-POSITIVE FIBRIN SPLIT PRODUCTS- POSITIVE PLASMINOGEN- DECREASED. ANTITHROMBIN III - DECREASED. BLOOD SMEAR – SCHISTOCYTES.

18. APPROACH TO PATIENTS WITH COAGULATION DISORDER

19. LABORATORY INVESTIGATIONS OF COAGULATION SYSTEM SCREENING TESTS- PROTHROMBIN TEST ACTIVATED PARTIAL THROMBOPLASTIN TIME THROMBIN TIME. 2 . CONFIRMATORY TESTS FOR FACTOR ABNORMALITIES . REPTILASE TIME. MIXING TESTS. FIBRINOGEN ASSAY.

20. TESTS TO EVALUATED CIRCULATING INHIBITORS

21. SCREENING TESTS

22. PROTHROMBIN TIME Principle: Measures the time for fibrin formation. Reflects the overall efficiency of the extrinsic system. Sensitive to changes in factor V, VIl and X, and less so to factor II (prothrombin). The sensitivity of the test is influenced by the reagent and technique used and it is important to establish a reference range locally.

23. Reagents Platelet poor plasma from the patient. Control plasma sample. Thromboplastin (this may contain calcium chloride). Calcium chloride - 0.025 mol/lit (only required if thromboplastin reagent does not contain calcium).

24. CAUSES OF PROLONGED PT Administration of oral anticoagulants drugs (vitamin K anticoagulants). Liver diseases Vitamin K deficiency DIC Previously underdiagnosed factor VII, X, V or prothrombin deficiency or defect.

25. ACTIVATED PARTIAL THROMBOPLASTIN TIME Principle: Measures the clotting time of plasma after the activation of contact factors but without added tissue thromboplastin. Indicates the overall efficiency of the intrinsic pathway. It is also sensitive to circulating anticoagulants (inhibitors) and heparin. Depends on contact factors, factors VIll , IX as well as X, V, prothrombin and fibrinogen.

26. REAGENTS  Kaolin 0.5gm in 100ml barbitone buffered saline, pH 7.4 Other can be used like silica, celite or elagic acid can be used. Phospholipid. Calcium chloride 0.025M Platelet poor plasma

27. METHOD 1-Mix equal volumes of phospholipid reagent and the kaolin kaolin suspension and leave in a glass tube in the water bath at 37 degree. 2-Place 0.1ml of plasma into a new glass tube. 3-Add 0.2ml of kaolin-phospholipid solution, mix the contents and start the stopwatch simultaneously. 4-Leave at 37 degrees for 10mins with occasional shaking. 5-At exactly 10mins, add 0.1ml of pre-warmed CaCi2 and start a second stopwatch. 6-Record the time taken for the mixture to clot. 7-Repeat the test on both the patient and the control plasma atleast once.

28. INTERPRETATION Normal range: 30 - 40 seconds. • A prolonged APTT with a normal PT indicates a possible deficiency of factor VIII, IX, XI, XIl , high molecular weight kininogen, prekallikrein or the presence of an inhibitor.

29. CAUSES OF PROLONGED aPTT DIC  LIver diseases Massive transfusion with stored blood. Administration of heparin or contamination with heparin. • A circulating anticoagulant. Deficiency of coagulation factor other than factor VIl

30. THROMBIN TIME Principle: • The thrombin time reflects the reaction between thrombin and fibrinogen. thrombin Fibrinogen Fibrin Thrombin is added to the plasma and the clotting time is. measured. The Thrombin time is affected by the concentration and reaction of fibrinogen, and by the presence of inhibitory substances, including fibrinogen/FDP and heparin.

31. REAGENTS PLATELET POOR PLSMA. THROMBIN SOLUTION WHICH INDUCES CLOTTING OF NORMAL PLASMA IN ABOUT 15 SECONDS. NORMAL RANGE- 15 – 19 secs.

32. METHOD-MANUAL  Pipette 0.2 ml test and control plasma into separate glass clotting tubes. Warm to 37°C. Add 0.1 ml thrombin solution to each tube. Start stopwatch for each tube. Measure the clotting time and observe the nature of clot. Repeat procedure for patient and control plasma.

33. CAUSES OF PROLONGED TT Hypofibrinogenaemia as found in DIC and, more rarely, in a congenital defect or deficiency. Raised concentrations of FDP, as encountered in DIC or liver disease. Extreme prolongation of the TT is nearly always a result of the presence of unfractionated heparin.  Dysfibrinogenaemia , either inherited or acquired, in liver disease or in neonates.  Hypoalbuminaemia .

34. CONFIRMATORY TESTS

35. REPTILASE OR ANCROD TIME Principle- It is a serine protease, a thrombin like enzyme. Cleaves fibrinopeptide A from fibrinogen. (thrombin cleaves both A &B). Method Addition of reptilase to platelet poor plasma initiates clot formation. Clot formation detected by optical/ electromechanical methods.

36. CAUSES OF PROLONGED RT/AT

37. MIXING TESTS

38. The agents which can be used for mixing tests are as follows -  Normal plasma. Aged plasma. Adsorbed plasma. Factor VIll deficient plasma. Factor Ix deficient plasma.

39. TESTS TO EVALUATE CIRCULATING INHIBITORS

40. CLOTTING FACTOR INHIBITOR SCREEN BASED ON PT/APT Principle- Coagulation inhibitors affecting the PT/APTT may be immediate acting or time dependent Test plasma containing an immediate-acting inhibitor will, when mixed with normal plasma, show little or. no correction of the clotting time. Plasma with time-dependent inhibitors, on the other hand, requires a period of incubation with normal plasma before inhibitors can be detected .

41. LUPUS ANTICOAGULANT AND ANTIPHOSPHOLIPD ANTIBODIES The criteria for presence of lupus anticoagulants are as follows: Prolongation of a phospholipid-dependent coagulation test; Evidence of an inhibitor demonstrated by mixing studies; Phospholipid dependency of the inhibitor.

42. LAB INVESTIGATIONS OF FIBRINOLYTIC SYSTEM

43. DETECTION OF FIBRIN DEGRADATION PRODUCTS USING A LATEX AGGLUTINATION METHOD Principle- A suspension of latex particles is sensitized with specific antibodies to purified FDP. The suspension is mixed on a glass slide with a dilution of the serum to be tested. Aggregation indicates presence of FDPs. Hence, by testing different dilutions of the unknown sample, a semi quantitative assay can be performed.

44. Conditions with the range between 10 - 40g μ/ ml are: Acute venous thromboembolism Acute MI Severe pneumonia Very high levels are seen in: DIC Thrombolytic therapy with streptokinase.

45. D-DIMER TEST Principle- • D-dimer is a marker specific for plasmin degradation of fibrin. Its an FDP generated from FXIlla crosslinked fibrin. Latex beads are coated with a monoclonal antibody directed specifically against fibrin D dimer in human plasma or serum. Reagents- Latex suspension Dilution buffer Positive & negative control.

46. METHOD Undiluted plasma is mixed with one drop of latex plasma. suspension on a glass slide. Gently rock the slide for the length of time mentioned in the kit. If agglutination is observe then dilute the plasma until agglutination can no longer be seen.

47. INTERPRETATION - Agglutination with undiluted plasma - D-dimer > 200mg/L. - The D-dimer value can be quantified by multiplying reciprocal of the highest dilution showing a positive result by 200 to give a value in mg/L. NORMAL RANGE: <200 mg/L.

48. Non- venous thromboembolism Causes of Elevated D-Dimer

49. SUMMARY A patient with a coagulopathy is much more likely to suffer bleeding in multiple sites , whereas a patient with a structural lesion often has blood loss from a single site. A positive history of bleeding in the family or a past history of bleeding since childhood are clues that a hereditary coagulation disorder is present. Hematomas, hemarthrosis, and mucous membrane bleeding are characteristic of severe coagulation factor deficiencies . Breakthrough bleeding can subsequently develop as a result of impaired fibrin formation due to coagulation factor abnormalities. Coagulation testing typically begins with a platelet count, PT and PTT.