MLAB 1227: Coagulation Keri Brophy
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Transcript MLAB 1227: Coagulation Keri Brophy
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: amount 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
Platelet Disorders
Bleed from ruptured
Bleed from capillaries
arterioles
Deep muscular & joint
bleeding
Delayed bleeding
Ecchymoses
Hematuria
No petechiae
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 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
Mucosal bleeding
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, XII, 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.