HEMOSTASIS AND THROMBOSIS
HEMORRHAGIC AND COAGULATION DISORDERS HEMORRHAGE is a severe form of bleeding that requires intervention.
Classification of Hemorrhage: LOCALIZED - single location; commonly indicates injury, infection, tumor, or an isolated blood vessel defect GENERALIZED – spontaneous, spontaneous, recurring bleeding from multiple sites (coagulopathies)
o
**Note: coagulopathies are generalized bleeding that usually requires intervention
ACQUIRED Acquired coagulopathy of Trauma-shock (ACOTS) o o Liver disease
Procoagulant deficiency Prolonged PT (factor VII) is an early marker. Declining coagulation Factor V activity – more more sensitive sensitive marker. Increased fibrinogen (APR); dysfibrinogenemia LIVER FAILURE – fibrinogen fibrinogen level tends to be extremely low Reptilase time – confirm confirm dysfibrinogenemia; uses Bothrops atrox (common lancehead viper) Platelet abnormalities Disseminated Intravascular Coagulation caused by decreased liver production of regulatory antithrombin, protein pr otein C, or protein S and by the release of activated procoagulants from degenerating liver cells failing liver cannot clear activated coagulation factors Acute uncompensated DIC – prolonged prolonged PT, PTT, TT, decreased fibrinogen, increased FDP Chronic compensated DIC – (+) (+) D-dimer test
o o
Renal failure and hemorrhage hemorrhage Vitamin K deficiency
o o o
Sources: green leafy vegetables, fish, liver, synthesized by intestinal flora (Bacteroides fragilis and Escherichia coli ) Cause of deficiency: insufficient dietary intake, biliary duct obstruction, fat malabsorption, chronic diarrhea, broad spectrum antibiotics suppressing the normal flora Hemorrhagic disease of the Newborn due to Vitamin K deficiency PIVKA – Proteins Proteins in Vitamin K antagonism (warfarin treatment)
Autoanti-VIII Inhibitor and Acquired Hemophilia Acquired von Willebrand disease DIC
CONGENITAL
-
Relatives with similar bleeding symptoms Onset of bleeding in infancy or childhood Bleeding from umbilical cord or circumcision wound Repeated hemorrhages in childhood, adulthood Hemorrhage into joints, central nervous system, soft tissues, peritoneum o
Von Willebrand Disease
most prevalent congenital bleeding disorder qualitative and structural abnormalities in vWF decreased platelet adhesion IMPAIRED PRIMARY HEMOSTASIS synthesized in the endoplasmic reticulum of endothelial cells and stored in cytoplasmic Weibel-Palade bodies of endothelial cells synthesized in megakaryocytes and stored in the α-granules of platelets most common Type 1 von Willebrand Disease – most Type 2 von Willebrand Disease Subtype 2A von Willebrand Disease
Clarence Witty H. Mendoza, RMT| 1
HEMOSTASIS AND THROMBOSIS
Subtype 2B von Willebrand Disease Subtype 2M von Willebrand Disease Subtype 2N von Willebrand Disease ( Normandy Variant or Autosomal Hemophilia) Type 3 von Willebrand Disease
Treatment: Mild bleeding: RICE (rest, ice, compression, elevation) Moderate bleeding: estrogen and desmopressin acetate , which trigger the release of VWF from storage organelles ε-Aminocaproic acid (EACA; Amicar) or tranexamic acid (Cyklokapron) inhibits fibrinolysis and may help control bleeding when used alone or in conjunction with desmopressin acetate.
TERM
MEANING
VIII/VWF
Customary term for the plasma combination of factor VIII and VWF. Procoagulant factor VIII, the protein transported on VWF. Factor VIII binds activated factor IX to form the complex of VIIIa-IXa, which digests and activates factor X. Factor VIII deficiency is called hemophilia A. Epitope that is the antigenic basis for the VWF immunoassay Ristocetin cofactor activity, also called VWF activity. VWF activity is measured by the ability of ristocetin to
VIII
VWF:Ag VWF:Rco
cause agglutination of reagent platelets by the patient’s
VIII:C
o
VWF. Factor VIII coagulant activity as measured in factorspecific clot-based assays.
Hemophilia A/ Classical Hemophilia
are congenital single-factor (Factor VIII)deficiencies marked by anatomic soft tissue bleeding Clinical Manifestation: anatomic bleeds with deep muscle and joint hemorrhages (hemarthroses) Hematomas wound oozing after trauma or surgery bleeding into the central nervous system, peritoneum, gastrointestinal tract, and kidneys Diagnosis: Patient history Abnormal bleeding in the neonatal period, Severe hemophilia usually is diagnosed Factor VIII Activity assay Hemophilia A carrier detection - VIII : VWF ratio Treatment desmopressin acetate in the form of DDAVP or Stimate (nasal formulation), alone or in combination with an antifibrinolytic such as Amicar or Cyklokapron When desmopressin acetate treatment proves ineffective, intravenous factor VIII concentrates are the next option
o
Hemophilia B/ Christmas Disease
o
Factor IX deficiency Indistinguishable from Hemophilia B Sex linked The PTT typically is prolonged, whereas the PT is normal. Factor IX assay should be performed even if PTT is within the reference range, because the PTT reagent may be insensitive to mild factor IX deficiency
Hemophilia C/ Rosenthal’s Disease
autosomal dominant hemophilia with mild to moderate bleeding symptoms Ashkenazi Jews frequent infusions of FP during times of hemostatic challenge
Clarence Witty H. Mendoza, RMT| 2
HEMOSTASIS AND THROMBOSIS
MUCOCUTANEOUS o
Purpura
Hemorrhage of blood into small areas of skin, mucous membranes, and other tissues. Bruises (purple lesions) due to extravasated (seeping) RBCs Petechiae o Purplish red pinpoint hemorrhagic spots in the skin Caused by loss of capillary ability to withstand normal blood pressure and trauma. Purpura less than 3 mm o Ecchymosis Form of purpura in which blood escapes into large areas of skin and mucous membranes, but not into deep tissues. Purpura greater than 3 mm Menorrhagia - excessive menstrual bleeding o o Hematemesis - vomiting of blood Epistaxis - uncontrolled nosebleed o ANATOMIC (SOFT TISSUE) – mostly internal o Examples of anatomic bleeding include recurrent or excessive bleeding after: minor trauma, dental extraction, surgical procedure o Hemarthrosis - leakage of blood into joint cavities Hematoma - swelling or tumor in the tissues or a body cavity that contains clotted blood o o Hematuria - red blood cell in urine o Hemoglobinuria - hemoglobin in urine o Melena - stool containing dark red or black blood.
Screening Tests for a Generalized Hemostatic Disorders TEST Hgb, Hct, reticulocyte count Platelet count PT PTT Thrombin time
ASSESES FOR
Anemia associated with chronic bleeding; bone marrow response Thrombocytopenia Deficiencies of factors II (prothrombin), V, VII, or X (clotting time prolonged) Deficiencies of all factors except VII and XIII (clotting time prolonged) Hypofibrinogenemia and dysfibrinogenemia
THROMBOSIS RISK TESTING Thrombosis
-
inappropriate formation of platelets or fibrin clots that obstructs blood vessels. common cause of stroke and heart attack due to are caused by thrombi that block coronary or carotid arteries
-
Risk factors: o o o
Increased homocysteine Immobilization of extremities Increased high-sensitivity C-reactive protein
Thrombophilia - congenital abnormalities that increase the risk of thrombosis; factor V Leiden is one such
risk factor. - Causes of thermophilia: o Physical, chemical, or biologic events such as chronic or acute inflammation that release prothrombotic mediators from damaged blood vessels or suppress blood vessel production of normal antithrombotic substances Inappropriate and uncontrolled platelet activation o o Uncontrolled triggering of the plasma coagulation system Inadequate control of coagulation-impaired fibrinolysis o Deep vein thrombosis
-
Entire leg swelling Symptoms: sensation of heat, localized pain, redness, and swelling
Clarence Witty H. Mendoza, RMT| 3
HEMOSTASIS AND THROMBOSIS Arterial thrombosis
-
About 80% of myocardial infarctions and 85% of strokes are caused by thrombi that block coronary arteries or carotid end arteries of the vertebrobasilar system, respectively Mechanism: atherosclerotic plaque formation in the vessel walls
Embolus - forms when a piece of a thrombus breaks off and travels to another location via the circulatory
system.
Thrombosis Risk Factors 1. Acquired Thrombosis Risk Factors habits and conditions that either maintain or damage our hemostasis systems o o E.g. age, immobilization, diet, lipid metabolism imbalance, oral contraceptive use, pregnancy, hormone replacement therapy, femoral or tibial fracture, hip, knee, gynecologic, smoking, inflammation, central venous catheter prostate surgery o 2. Thrombosis Risk Factors Associated with Systemic Diseases conditions and diseases threaten us with thrombosis o o E.g. Antiphospholipid syndrome, myeloproliferative neoplasms, hepatic and renal disorders, cancer, leukemia, paroxysmal nocturnal hemoglobinuria, chronic inflammation 3. Congenital Thrombosis Risk Factors suspected when a thrombotic event occurs in young adults o o occurs in unusual sites such as the mesenteric, renal, or axillary veins; is recurrent; or occurs in a patient who has a family history of the disorder o E.g. Anti-thrombin deficiency (previously called as AT-III deficiency), Protein C deficiency, free Protein S deficiency, Activated protein C resistance, Prothrombin G20210A, dysfibrinogenemia and afibrinogenemia, plasminogen mutations, tissue plasminogen activator deficiency, PAI-1 deficiency 4. Double Hit o Thrombosis often is associated with a combination of genetic defect, disease, and lifestyle influences.
Laboratory Evaluation of Thermophilia 1. Antiphospholipid Antibodies
-
family of immunoglobulins that bind protein-phospholipid complexes APL antibodies arise as immunoglobulin M (IgM), IgG, or IgA isotypes Called non-specific inhibitors because they may bind a variety of protein-phospholipid complexes Agents Known to Induce Antiphospholipid Antibodies Various antibiotics Phenothiazine Hydralazine Quinine and quinidine Calcium channel blockers Procainamide Phenytoin Cocaine Elevated estrogens
-
Lupus anticoagulant Platelets contain phospholipid in their membrane, and this can overcome and thus mask the lupus anticoagulant when it is present. Thus both the patient and the normal plasma used for mixing studies must be platelet poor. The phospholipid concentration in the reagent used for detection must also have a low concentration of phospholipid to be sensitive. The initial test before the 1:1 mix must be prolonged to even suggest the possible presence of the lupus anticoagulant, providing a lupus anticoagulant – sensitive reagent is used.
-
Anticardiolipin Antibody Immunoassay
-
prolonged PTT characterized by lack of correction when the patient plasma is mixed 1:1 with normal platelet poor plasma and the PTT repeated not affected by heparin therapy, oral anticoagulant therapy, current thrombosis, or factor deficiencies
Anti –ß2-Glycoprotein I Immunoassay Antiphosphatidylserine Immunoassay
2. Activated Protein C Resistance and Factor V Leiden Mutation
Clarence Witty H. Mendoza, RMT| 4
HEMOSTASIS AND THROMBOSIS most common congenital disorder of excess thrombosis in whites (occurs in 3% to 8% of whites) Activated factor V Leiden is resistant to degradation by activated protein C, which is critical for slowing down thrombin generation. This results in an increased thrombotic risk for the patient. 3. Prothrombin G20210A 4. Anti-thrombin
Antithrombin is a serine protease inhibitor (serpin) that neutralizes factors IIa (thrombin), IXa, Xa, XIa, and XIIa Antithrombin activity is enhanced by unfractionated heparin, low-molecular-weight heparin, and synthetic pentasaccharide Anti-thrombin deficiency o Acquired – anti-thrombin is rapidly consumed occurs in liver disease, nephrotic syndrome, with prolonged heparin therapy, with asparaginase therapy, with the use of oral contraceptives, and in DIC Congenital o
Chromogenic assay for antithrombin o
o
o o
o o o
Antithrombin concentration is inversely proportional to the intensity of end-product color. Heparin is added to the patient plasma before testing to improve sensitivity to antithrombin. A protease, often Xa, is added in excess to an aliquot of the patient sample. Some of this Xa will be bound by the heparin-antithrombin complex and thus inhibited. After this, a chromogenic substrate is added that is specific for Xa. When the residual Xa hydrolyzes this substrate, color will be released. The more antithrombin present in the patient sample, the more Xa will be bound and the less chromogen will be released.
Heparin therapy o
Patients on heparin must have platelet counts performed daily. A significant drop in the platelet count is a signal for heparin-induced thrombocytopenia. The PTT is also regularly performed to monitor the heparin dosage.
5. Protein C Control Pathway Chromogenic assay for Protein C o
A specific snake venom is used to activate protein C in its chromogenic assay to determine its concentration
Chromogenic assay for Protein S o Clot-based assay is performed by mixing the patient’s plasma with protein S– o
depleted normal plasma to ensure normal levels of all other factors. APC and Russell viper venom in a buffer that contains a heparin neutralizer are added, followed by calcium chloride, and the interval to clot formation is measured.
Arterial Thrombotic Predictors -
Arterial thrombotic disease in the form of peripheral vascular disease, myocardial infarction (heart attack), and cerebrovascular disease (stroke) arises from atherosclerosis. Predictors: Elevated total cholesterol and low-density lipoprotein cholesterol (LDLC), or a high ratio of total cholesterol to high-density lipoprotein cholesterol (TC : HDL -C) secondary to deficient HDL-C C-Reactive Protein o
Acute phase reactant that can be directly correlated to acute myocardial infarction
Plasma Homocysteine Fibrinogen activity o
o
o
Elevated fibrinogen makes blood more viscous, which favors coagulation, platelet activation, and formation of atherothrombotic lesions. It directly promotes platelet activation by binding to their glycoprotein IIb/IIIa membrane receptors. Because fibrinogen becomes integrated into atherothrombotic lesions, it contributes to their thrombotic potential
Lipoprotein (a) o
an LDL with noteworthy thrombosis risk prediction characteristics Clarence Witty H. Mendoza, RMT| 5
HEMOSTASIS AND THROMBOSIS o
may contribute to thrombosis by its antifibrinolytic property
Disseminated Intravascular Coagulation (DIC) -
thrombotic process wherein the thrombi formed are small and ineffective, so systemic hemorrhage is often the first or most apparent symptom can have severe hemorrhaging and is often fatal, requiring immediate medical intervention Laboratory results: D-dimer and fibrin split products are elevated. The platelet count is expected to be low, with an elevated PT, PTT, and TT. Schistocytosis is present in 50% of the patients. Thrombocytopenia is expected, along with anemia because red cells are being destroyed in circulation. **Note: Other cases where D-dimer may be increased: embolus, deep vein thrombosis
-
Sepsis-induced DIC – noticeably high fibrinogen since it is an acute phase reactant Treatment: o o o
Antithrombin and protein C concentrates Platelet transfusions and fresh frozen plasma (FFP) Heparin
Clarence Witty H. Mendoza, RMT| 6
