Acquired Flashcards
What is defined as a massive blood transfusion?
Transfusion of one’s entire blood volume within 24 hours, transfusion of half (50%) of total blood volume in 3 hours, transfusion of >10 units of packed red cells in 24 hours, or transfusion of >4 units in 1 hour.
What deficiencies are typically found in stored blood?
Deficient in platelets and some coagulation factors (F V and VIII).
What causes haemostatic defects in massively transfused patients?
Dilution of platelets and coagulation factors.
What is the major role of the liver in haemostasis?
Synthesizes coagulation factors and natural anticoagulants, utilizes vitamin K for synthesis of vitamin K dependent proteins, and clears activated coagulation factors and plasminogen activators.
What are common causes of bleeding in liver disease?
- Oesophageal varices (portal hypertension)
- Thrombocytopenia
- Deficient synthesis of coagulation factors
- Deficient utilization of vitamin K
- Disseminated intravascular coagulation (DIC)
- Increased fibrinogenolysis
- Defective platelet function
- Synthesis of defective fibrinogens.
What laboratory findings are associated with liver disease?
- Prolonged PT
- Prolonged APTT
- Prolonged TT
- VWF normal
- Low platelet.
What management strategies are recommended for liver disease-related bleeding?
- Fresh frozen plasma
- Prothrombin complex concentrate
- Supply vitamin K dependent factors
- Vitamin K
- Fibrinolytic inhibitors if no DIC.
What is Vitamin K deficiency bleeding (VKDB)?
A condition where levels of vitamin K-dependent clotting factors are depressed in newborns, leading to bleeding.
What are the presentations of early, classical, and late VKDB?
- Early VKDB: First 24 hours of life
- Classical VKDB: Days 2-7 of life
- Late VKDB: Day 8 to 6 months of life.
What causes early VKDB?
Infants of mothers on vitamin K-inhibiting drugs.
What is the diagnostic criterion for VKDB?
A Prothrombin Time (PT) more than four times control with a normal platelet count, normal fibrinogen level, and absent fibrinogen degradation products.
What are the treatment options for VKDB?
Prophylaxis with oral vitamin K, IV vitamin K for active bleeding, and monitoring PT correction.
What is the role of vitamin K in the body?
Vitamin K is a fat-soluble vitamin essential for synthesizing certain coagulation factors.
What are common causes of vitamin K deficiency?
- Haemorrhagic disease of the newborn
- Poor dietary intake
- Impaired absorption
- Drugs like anticoagulants (e.g., Warfarin)
- Broad-spectrum antibiotics.
What are specific inhibitors in coagulation disorders?
Antibodies that inhibit the activity of specific coagulation factors, including FVIII, FIX, fibrinogen, and von Willebrand factor.
What is Acquired Haemophilia A?
A rare autoimmune bleeding disorder due to auto-antibodies against endogenous FVIII.
What are the clinical manifestations of Acquired Haemophilia A?
- Widespread subcutaneous bleeding
- Haematomas
- GI and GU bleeding
- Neurovascular compression may be limb-threatening.
What is the pathogenesis of disseminated intravascular coagulation (DIC)?
Involves a fibrinolytic defect and the role of cytokines, with sepsis being the most common trigger.
What laboratory findings are indicative of acute DIC?
- Prolonged PT, APTT, and TT
- Reduced fibrinogen level
- Increased D-Dimers/FDP
- Reduced platelet count.
What is the treatment for lupus anticoagulant?
Long-term anticoagulant therapy is frequently required in patients with thrombosis.
What are the types of antiphospholipid antibodies?
- Anticardiolipin antibodies
- Anti-b2-glycoprotein I antibodies
- Lupus anticoagulant.
What are common laboratory findings in chronic DIC?
- PT, APTT normal
- Platelet count normal
- FDP and D-dimer increased.
What is acquired von Willebrand syndrome associated with?
An autoantibody, typically in the context of monoclonal gammopathy or other hematological disorders.
What is the significance of the presence of proteins induced by vitamin K absence or antagonism (PIVKA)?
It is a marker of subclinical vitamin K deficiency.
What is the effect of anticoagulants like Warfarin on vitamin K?
They inhibit the enzyme epoxide reductase, preventing the recycling of vitamin K.
What are the treatment options for acquired factor V deficiency?
- Fresh frozen plasma
- Platelets may be useful in resistant cases.
What are the clinical manifestations of renal disease related to coagulation disorders?
Excessive urinary loss of factor IX and antithrombin III in nephrotic syndrome.
What is the typical presentation of acquired protein S deficiency?
Patients present with skin necrosis and DIC.
What triggers disseminated intravascular coagulation (DIC) among medical or surgical inpatients?
The production of endotoxin by the offending organism activates monocytes, provoking the release of endogenous tissue factor and inflammatory cytokines.
What cytokines are involved in coagulation activation in DIC?
IL-6, IL-1, TNF-α
What is immune thrombocytopenia (ITP)?
An acquired, autoimmune disorder with the formation of antiplatelet antibodies against platelets and megakaryocytes.
What are the two phases of immune thrombocytopenia (ITP)?
- Primary ITP: autoimmune disorder with isolated thrombocytopenia
- Secondary ITP: all other forms of ITP except primary, e.g., drug-induced, associated with infections
What is the threshold for ITP and clinical thrombocytopenia?
A platelet count <100 × 10^9/L
What are common causes of thrombocytopenia?
- Central (production failure)
- Peripheral (reduced survival)
What is a characteristic symptom of platelet defects?
Mucocutaneous bleeding
What is the treatment for Scurvy, a vascular defect?
Vitamin C 200 mg daily
What are the clinical features of Henoch-Schönlein purpura?
- Abdominal colic
- Arthritis
- Nephritis
- Palpable purpura
What is the typical onset of acute ITP in children?
Abrupt onset of thrombocytopenia, often preceded by a viral illness.
What is the female-to-male ratio for chronic ITP?
3:1
What are the signs and symptoms of ITP?
Bleeding into the skin and mucosal surfaces (petechiae, ecchymoses)
What laboratory findings are indicative of ITP?
- Prolonged bleeding time
- Normal PT and PTT
- Low platelet count
What is the goal of treatment for ITP?
To stop bleeding and increase platelet count to a safe level.
What therapeutic agents are used for ITP?
- Oral corticosteroids
- IV immune globulin (IVIG)
- IV anti-D immune globulin
- Thrombopoietin receptor agonists (TPO-RA)
- Rituximab
- Fostamatinib
What characterizes disseminated intravascular coagulation (DIC)?
Systemic activation of blood coagulation leading to microvascular thrombi and multiple organ dysfunction syndrome (MODS).
What are common causes of DIC?
- Gram-negative and meningococcal septicaemia
- Severe falciparum malaria
- Viral infections
- Amniotic fluid embolism
- Incompatible blood transfusion
What are the three mechanisms characterizing the pathogenesis of DIC?
- Intravascular activation of extrinsic pathway of coagulation
- Reduction in levels of endogenous anticoagulants
- Suppression of the fibrinolytic system
What is hemostasis?
The mechanism that leads to cessation of bleeding from a blood vessel.
What are the major components of hemostasis?
- Procoagulant mechanisms
- Anticoagulant mechanisms
- Fibrinolysis
What are the stages of hemostasis?
- Constriction of the blood vessel
- Formation of a temporary platelet plug
- Activation of the coagulation cascade
- Formation of fibrin plug or final clot
What are the basic laboratory tests for diagnosing acquired bleeding disorders?
- Partial thromboplastin time (PTT)
- International normalized ratio (INR)
- Full blood count with peripheral blood smear
What are acquired bleeding disorders?
The most common causes of bleeding seen in hematology practice, due to interference with platelet plug formation or blood coagulation proteins.
