DISODERS OF SECONDARY HEMOSTASISDisorders of plasma clotting factors

DISORDERS OF SECONDARY HEMOSTASIS Disorders of the proteins of fibrin formation Disorders of proteins associated with

fibrinolysis Symptoms of secondary hemostatic disorders

Delayed bleeding Deep muscular bleeding Spontaneous joint bleeding Symptoms common to primary and secondary

hemostatic disorders Ecchymoses GI bleeding Hematuria Hypermenorrhea Gingival bleeding Increased bleeding after tooth extraction Intracranial bleeding Epistaxis

Hereditary vs acquired Quantitative vs qualitative deficiencies

Laboratory screening tests (PT, APTT) Does not differentiate quantitative vs qualitative disorders

Qualitative abnormal proteins will Prolong clotting test Be recognized by immunologically-based procedures

Activity assays Essential when screening for deficiencies

DISORDERS OF PROTEINS OF FIBRIN FORMATION

COAGULATION SCREENING TESTS IN CONGENITAL DEFICIENCIES

Platlet count

PT APTT PFA TT Congenital Deficiency

N N N N N XIII, mild deficiency of any factor, plasminogen activator inhibitor-1, α2 anti-plasmin

N A N N N VII

N N A N N XII, XI, IX, VIII, prekallikrein, high molecular weight kininogen

N A A N N X, V, II

N A A N A Fibrinogen

N N A or N A or N N Von Willibrands

Inherited hemorrhagic disorder Genetically and clinically heterogeneous Caused by a deficiency/dysfunction of VWF Most common hereditary bleeding disorder

VWF Multimeric blood protein Performs two major roles in hemostasis

Mediates adhesion of platelets to sites of vascular injury Is a carrier protein for F-VIII

Inherited defects in VWF may Interfere with biosynthetic processing or disrupt specific

ligand binding sites Cause bleeding by impairing either platelet adhesion or

blood clotting

VON WILLEBRAND DISEASE

Three major categories of VWD Type 1 VWD – partial quantitative deficiency of VWF Type 2 VWD – qualitative deficiency of VWF

Divided into 4 variants Type 2A – ↓ platelet-dependent function

Absence of high-molecular weight VWF multimers Type 2B – ↑ affinity for platlet GPIb Type 2M – ↓ platelet-dependent function

Not caused by the absence of HMW multimers Type 2N – Markedly ↓ affinity for F-VIII

Type 3 VWD – total deficiency of VWF Types 1 and 2 – autosomal dominant inheritance Type 3 – autosomal recessive inheritance

Diagnosis Specific tests

Quantify VWF and F-VIII activity

VWD

Hemorrhagic tendency is highly variable Depends on the type and severity of disease Patients with Type 1 and 2 disease

May have mild bleeding symptoms Characterized by hemorrhage from delicate mucocutaneous

tissues Epistaxis, easy bruising, GI bleeding, menorrhagia Hematoma and hemarthroses, characteristic of hemophilia A, are

not prominent Patients with severe type 3 VWD

Severe hemorrhagic tendency Spontaneous hemorrhage

Mucous membranes, GI tract Can be frequent and may be life threatening

Low F-VIII level Deep hematomas Joint hemorrhages – similar to hemophilia

VWD – CLINICAL MANIFESTATIONS

Goal Correct both bleeding time and coagulation

abnormalities Raise both F-VIII and VWF to normal levels

Desmopressin acetate (DDAVP) stimulates release of vWF from endothelial cells – won’t work for type 3

Intermediate purity factor VIII which contains intact vWF

VWD – THERAPY

Hemophilia A Factor VIII Deficiency

Antihemophilic Factor X-linked recessive disorder Most common type of hemophilia

Hemophilia B Factor IX Deficiency

Christmas Factor (from family of first patients diagnosed with the disorder)

X-linked recessive disorder Hemophilia C

Factor XI Deficiency Autosomal recessive disorder seen primarily in the

Ashkenazi Jewish population Symptoms range from mild to severe

HEMOPHILIAS

COAGULATION SCREENING TESTS IN CONGENITAL DEFICIENCIES

Platlet count

PT APTT PFA TT Congenital Deficiency

N N N N N XIII, mild deficiency of any factor, plasminogen activator inhibitor-1, α2 anti-plasmin

N A N N N VII

N N A N N XII, XI, IX, VIII, prekallikrein, high molecular weight kininogen

N A A N N X, V, II

N A A N A Fibrinogen

N N A or N A or N N Von Willibrands

Insufficient generation of thrombin by F-IXa/VIIIa complex through the intrinsic pathway of

coagulation cascade Bleeding severity complicated by excessive fibrinolysis

Clinical severity corresponds with level of factor activity

Severe hemophilia Factor coagulant activity <1% of normal Frequent spontaneous bleeding into joints and soft

tissues Prolonged bleeding with trauma or surgery

HEMOPHILIA

Moderate hemophilia Factor coagulant activity 1-5% of normal Occasional spontaneous bleeding Excessive bleeding with surgery or trauma

Mild hemophilia Factor coagulant activity >5% of normal Usually no spontaneous bleeding Excessive bleeding with surgery or trauma

HEMOPHILIA

Readily diagnosed In severe disease and patients with prior family history

Diagnosis based on Unusual bleeding symptoms early in life Age of first bleeding varies with severity of disease Family history Physical exam Laboratory evaluation

HEMOPHILIA – CLINICAL PRESENTATION

Replacement of clotting factor to achieve hemostasis Annual cost for patient with severe hemophilia

$20,000-100,000 Various products available

Plasma-derived low, intermediate and high purity products Plasma-derived ultrapure products Ultrapure recombinant products

Replacement products – benefits vs risks Blood-born pathogens

Hepatitis A, B, C, G; HIV, Parvovirus B-19 Thrombotic complications with some F-IX concentrations Development of alloantibody inhibitors

Neutralize coagulant effects of replacement therapy

HEMOPHILIA – TREATMENT

More common than hereditary disorders Usually involve defects of multiple hemostatic factors Bleeding often simultaneously from >1 site May occur in response to another disease process Can be produced by a variety of mechanisms

ACQUIRED DISORDERS

Normal balance of hemostasis is altered Results in the uncontrolled inappropriate formation and

lysis of fibrin within the blood vessels Activation of coagulation occurs systemically

Rather than locally at site of injury Fibrin is deposited diffusely within capillaries, arterioles

and venules Clotting proteins, inhibitors and platelets are

consumed faster than they are synthesized Acquired deficiency of multiple hemostatic components Fibrinolysis follows fibrin formation Patient generally bleeds spontaneously at the same time

that disseminated clotting is occurring

DISSEMINATED INTRAVASCULAR COAGULATION

CLINICAL CONDITIONS ASSOCIATED WITH DIC

Fibrin strands within small vessels result in Traumatic destruction of RBC

Microangiopathic hemolytic anemia Formation of schistocytes

Fibrin deposition in and obstruction of microvasculature Tissue anoxia/microinfarcts Renal failure, liver failure, respiratory failure, shock

and death

DIC - PATHOPHYSIOLOGY

DIC

HELLP syndrome High blood pressure Elevated liver enzymes Low platlets Occurs in pregnancy and is life-threatening If the CBC of a woman in labor shows

schistocytes and low platlets alert the physician immediately – the baby must be delivered immediately to save the mom!

Laboratory diagnosis is difficult Available tests are nonspecific No single test can establish the definitive diagnosis of

DIC PT, APTT, TT prolonged Fibrin degradation products are (+) Platelet count ↓; platelet function tests abnormal Schistocytes, thrombocytopenia on peripheral blood

smear

DIC – LABORATORY DIAGNOSIS

Eliminate underlying cause, if possible Acute DIC is often self-limited

Will disappear when fibrin is lysed Replacement therapy

Platelets, RBC, Cryoprecipitate or fresh frozen plasma

DIC – THERAPY

Precursor proteins synthesized by hepatocytes Not γ-carboxylated Ca++-binding sites are nonfunctional Induced functional deficiencies of all vitamin-K

dependent proteins Causes of vitamin K deficiency in adults

Malabsorptive syndromes Biliary tract obstruction Prolonged broad-spectrum antibiotics

Most often seen in newborns Hemorrhagic disease of the newborn

Due to newborn hepatic immaturity

VITAMIN K DEFICIENCY

Circulating anticoagulants Usually IgG or IgM immunoglobulins Inhibitors of single factors

Patients with inherited factor deficiencies After treatment with replacement concentrates

Associated with other conditions Diseases, drugs

Occasionally seen in otherwise healthy individuals Interfere with or neutralize clotting factor activity Prolonged screening test not corrected by 1:1 mixture with

normal plasma

ACQUIRED PATHOLOGIC INHIBITORS