MLAB 1227: Coagulation Keri Brophy-Martinez Coagulation Disorders: Secondary Hemostasis Part One Disorders of the Proteins of Fibrin Formation Fibrin formation ineffective and slowed so patient presents with abnormal bleeding Two categories Inheritance of a defective gene Failure of synthesis of a hemostatic protein Malfunction or impaired molecule Acquired Acquisition of a deficiency secondary to another condition Terms Quantitative: absence of a coagulation protein Qualitative: Present in plasma but functionally defective General Lab Features Lab PT prolonged aPTT prolonged Platelet count normal Clinical Findings Coagulation Factor Disorders Bleed from ruptured arterioles Deep muscular & joint bleeding Delayed bleeding Ecchymoses Hematuria No petechiae Platelet Disorders Bleed from capillaries Superficial bleeding Acute bleeding Ecchymoses Hematuria Petechiae Hereditary Disorders of Secondary Hemostasis Involve a single factor Bleeding originates from one site Factor VIII Deficiency Von Willebrand's Disease – lack of or defective VIII:vWF Autosomal dominant – seen in both males and females Most common inherited blood disorder Platelet abnormalities – adhesiveness and aggregation, bleeding times Von Willebrand's Disease Clinical Features Lab Findings Mild bleeding in mucosal & PTT normal or increased cutaneous tissues Easy bruising Hallmark is variability of symptoms PT normal Platelet count normal BT/ PFA abnormal Factor VIII Deficiency Hemophilia A – classical hemophilia Sex-linked recessive carried by female, manifested in the male Accounts for 80% of all hemophiliacs Deficiency of factor VIII portion of VIII/vWf complex Patient has normal circulating vWf Abnormal bleeding Caused by delayed and inadequate fibrin formation Caused by failure to form a stable plug at a damaged site Caused by a secondary increase in fibrinolysis Failure of TAFI Factor VIII Therapy Replace clotting factors to achieve hemostasis DDAVP (desamino-D-vasopressin) Stimulates storage cells to release VIII and vWF into plasma. Disadvantage is not all patients can take it Factor IX Deficiency – Hemophilia B, Christmas Disease <20% of all hemophiliacs Sex-linked recessive No Factor IX function Clinically indistinguishable from hemophilia A, so we see the same disease course Clinical Findings of Hemophilias Bleeding occurs with NO trauma or trivial injury Hemarthrosis Spontaneous bleeding into joints, causes extreme pain and destroys cartilage of knees, elbows, ankles Deep tissue hemorrhage – internally Hematuria CNS bleeding Factor XI Deficiency – Rosenthal's Disease or Hemophilia C <5% of all hemophiliacs Autosomal recessive Highest incidence in Jewish persons of Russian decent Prolonged PTT, normal PT Requires therapy only following childbirth or surgery Lab Features: Comparison vWD Factor VIII Deficiency Factor IX Deficiency Platelet count Normal Normal Normal Bleeding Time Normal-increased Normal Normal Platelet Function Assay Normal-increased Normal Normal PT Normal Normal Normal PTT Normal-increased Increased Increased Factor VIII Assay Normal-decreased Decreased Normal Factor IX Assay Normal Normal Decreased vWF: Ag Assay Decreased Normal Normal Congenital Disorders of the Other Factors The following factors are rarely deficient or defective to the extent that coagulation is slowed – I, II, V, VII, X, XIII Severity of bleeding dependent upon concentration of factor present PK and HMWK disorders do exist but patients do not have bleeding tendencies. References McKenzie, Shirlyn B., and J. Lynne. Williams. "Chapter 32." Clinical Laboratory Hematology. Boston: Pearson, 2010. Print.