Haematology 4

oelomar's version from 2016-03-31 19:06


Question Answer
Bleeding due to thrombocytopenia or abnormal platelet function is characterised by what?Purpura (particularly in the forearms) and bleeding from mucous membranes.
What is immune thrombocytopenic purpura?An autoimmune condition with antibodies detectable against several platelet surface antigens, in which there is an isolated low platelet count (thrombocytopenia) with normal bone marrow and the absence of other causes of thrombocytopenia. It causes a characteristic purpuric rash and an increased tendency to bleed.
What is the difference between acute and chronic immune thrombocytopenic purpura?The acute form often follows an infection and has a spontaneous resolution within two months. Chronic immune thrombocytopenia persists longer than six months with a specific cause being unknown. The acute form is more commonly seen in children, whereas the chronic form is more commonly seen in adults.
What is Evan’s syndrome?Immune thrombocytopenic purpura in associated with autoimmune haemolytic anaemia, i.e. it is an autoimmune disease in which an individual’s antibodies attack their own RBCs and platelets.
What are the clinical features of immune thrombocytopenic purpura?Easy bruising, purpura, epistaxis and menorrhagia are common. There may be a sudden onset of petechiae (small purpura), purpura, and/or epistaxis in an otherwise well child.
How is immune thrombocytopenic purpura treated?Most people do not usually require treatment. Where this is necessary, prednisolone is effective, given for a very short course. IV IgG should be reserved for very serious bleeding or urgent surgery.


Question Answer
What is heparin-induced thrombocytopenia and what does it predispose to?Development of thrombocytopenia (but generally not low enough to cause increased bleeding risk) due to the administration of various forms of heparin (mechanism is quite complex). It predisposes to thrombosis. Typically, the platelet count will fall 5-14 days after heparin is first given.
What is post-transfusion purpura?Post-transfusion purpura is a potentially fatal adverse reaction to a blood transfusion or platelet transfusion that occurs when the body produces alloantibodies to the introduced platelets' antigens. These alloantibodies destroy the patient's platelets leading to thrombocytopenia. PTP usually presents 5–12 days after transfusion.
What is thrombotic thrombocytopenic purpura (TTP)?A rare disorder of the blood-coagulation system, causing extensive microscopic clots to form in the small blood vessels throughout the body, leading to multi-organ micro-thrombi.
What are the clinical features of thrombotic thrombocytopenic purpura?The pentad of TTP is as follows: “FAT RN”: Fever; Anaemia (haemolytic); Thrombocytopenia (leading to purpura and bruising); Renal dysfunction; Neurologic abnormalities.
What will a coagulation screen show in patients with thrombotic thrombocytopenic purpura?It will be normal apart from the lactic dehydrogenase levels, which will be markedly raised as a result of haemolysis.
What are the causes of thrombotic thrombocytopenic purpura?The two forms of TTP and idiopathic and secondary. Secondary causes include pregnancy, oral contraceptives, systemic lupus erythematosus, infection, and drug treatment – including the use of ticlopidine and clopidogrel.
How is thrombotic thrombocytopenic purpura treated?Plasma exchange (removal of the plasma from the blood and replacement with new plasma) is the mainstay of treatment. Pulsed intravenous methylprednisolone and rituximab is given acutely.


Question Answer
What is hereditary haemorrhagic telangiectasia (Osler-Weber-Rendu syndrome)?An autosomal genetic disorder that leads to abnormal blood vessel formation in the skin, mucous membranes, and often in organs such as the lungs, liver and brain. Dilatation of capillaries and small arterioles produces characteristic small red spots that blanch on pressure in the skin and mucous membranes, particularly the nose and gastrointestinal tract.
What are the clinical features of Osler-Weber-Rendu syndrome?Recurrent epistaxis and chronic gastrointestinal bleeding are the major problems which causes chronic iron deficiency anaemia.
What is Glanzmann’s thrombasthenia?An inherited type of platelet dysfunction in which platelets contain defective or low levels of glycoprotein IIb/IIIa resulting in defective fibrinogen binding and failure of platelet aggregation.
What is Bernard–Soulier syndrome?An inherited type of platelet dysfunction in which platelets contain a lack of glycoprotein Ib, the receptor for von Willebrand factor. This causes a failure of platelet adhesion and moderate thrombocytopenia.
What is platelet storage pool deficiency?An inherited type of platelet dysfunction in which there are defects in the granules in platelets, causing poor platelet function.
Name some causes of thrombocytosis (high platelet count in the blood).Splenectomy (due to reduced destruction), malignant disease, inflammatory disorders such as rheumatoid arthritis and inflammatory bowel disease, major surgery and post haemorrhage, myeloproliferative disorders, iron deficiency.
Paradoxically, there is a risk of abnormal bleeding if the platelet count is very high. True or false?True.


Question Answer
What is haemophilia, and what are the two most common forms of this disorder?Haemophilia is a group of hereditary genetic disorders that impairs the body’s ability to control blood clotting. Haemophilia A (clotting factor VIII deficiency) is the most common form of the disorder, present in about 1 in 5,000–10,000 male births. Haemophilia B (factor IX deficiency) occurs in around 1 in about 20,000–34,000 male births.
What is haemophilia A?A genetic deficiency in clotting factor VIII which causes increased bleeding. About 70% of the time, it is inherited an x-linked recessive trait, but around 30% of cases arise from spontaneous mutations.
What are the clinical features of haemophilia A?Depends on the severity (i.e. on the level of factor VIII). Severe: Frequent spontaneous bleeding from early life, typically into joints and muscles, which could lead to joint deformity and crippling if no adequate treatment is given. Moderate: Severe bleeding following injury and occasional spontaneous bleeds. Mild: Bleeding only after injury or surgery.
How is haemophilia A treated acutely?Bleeding is treated by IV administration of factor VIII concentrate.
How is haemophilia A treated prophylactically?Severe haemophilia: Factor VIII infusions. Mild haemophilia: ADH (desmopressin).
What is haemophilia B?Also known as Christmas disease, this is a genetic deficiency in clotting factor IX. The inheritance and clinical features are identical to haemophilia A, but the incidence is lower.
How is haemophilia B treated?Factor IX administration. Prophylactic doses are given twice a week.
In haemophilia, the prothrombin time is normal, but the activated partial thromboplastin time is increased. True or false?True.
What is Von Willebrand disease?A deficiency or abnormality of VWF, which plays a role in platelet adhesion to damaged sub-endothelium as well as stabilising factor VII in plasma. It is the most common inherited bleeding disorder.
What are the different types of Von Willebrand disease, and how are they classified?Type 1: quantitative deficiency in VWF, i.e. partial reduction in vWF (80% of patients – autosomal dominant). Type 2: qualitative abnormality of vWF, i.e. abnormal form of vWF – autosomal dominant. Type 3: virtually a complete deficiency of VWF – automsomal recessive and the most severe from.
What are the clinical features of Von Willebrand disease?There are very variable. Type 1 and 2 patients usually have relatively mild clinical features. Bleeding follows minor trauma or surgery, and epistaxis and menorrhagia often occur. Haemarthroses (bleeding into joints) are rare. Type 3 patients have more severe bleeding but rarely experience the joint and muscle bleeds seen in haemophilia A.
How is Von Willebrand disease treated?Tranexamic acid for mild bleeding. Desmopressin may also be used. Some plasma-derived factor VIII concentrates contain intact VWF, and may therefore be used to treat bleeding or to cover surgery in patients who require replacement therapy.


Question Answer
Vitamin K is necessary for the binding of some coagulation factors to calcium. Which coagulation factors are they?Factors II, VII, IX, X, and protein C and S.
In vitamin K deficiency, the prothrombin time is raised, and so is the activated partial thromboplastin time. True or false?True.
What are the clinical features of vitamin K deficiency?There may be bruising, haematuria, and GI or cerebral bleeding.
What is haemorrhagic disease of the newborn?Also known as vitamin K deficiency bleeding, this is a coagulation disturbance in newborns due to vitamin K deficiency. It can result in minor bleeding in the first week of life, but can also cause late haemorrhagic disease of the newborn, which occurs 2–26 weeks after birth and results in severe bleeding such as intracranial haemorrhage.
How is vitamin K deficiency treated?Minor bleeding is treated with phytomenadione (vitamin K1) 10 mg intravenously. Haemorrhagic disease of the newborn can be prevented by administering 1 mg IM vitamin K to all neonates.


Question Answer
What is disseminated intravascular coagulation?A pathological process characterised by the widespread activation of the clotting cascade that results in the formation of blood clots in the small blood vessels throughout the body.
Name some causes of disseminated intravascular coagulation.Malignant disease, sepsis, haemolytic transfusion reactions, trauma, surgery, liver disease, snake bites.
What are the clinical features of disseminated intravascular coagulation?There is a mixture of initial thrombosis followed by a bleeding tendency due to consumption of coagulation factors and fibrinolytic activation. The underlying disorder is usually obvious. The patient is often acutely ill and shocked. The clinical presentation of DIC varies from no bleeding at all to profound haemostatic failure with widespread haemorrhage. Bleeding may occur from the mouth, nose and venepuncture sites and there may be widespread ecchymoses. Thrombotic events occur as a result of vessel occlusion by fibrin and platelets. Any organ may be involved, but the skin, brain and kidneys are most often affected.
The following are features in severe cases of disseminated intravascular coagulation with haemorrhage: Prolonged prothrombin time, activated partial thromboplastin time, thromboplastin time; reduced fibrinogen levels; high levels of fibrin-degradation products including d-dimer; thrombocytopenia; sometimes fragmented RBCs on blood film. True or false?True.
The following are features in mild cases of disseminated intravascular coagulation without bleeding: normal prothrombin time, activated partial thromboplastin time, thromboplastin time, and platelet counts; increased synthesis of coagulation factors and platelets; raised fibrin-degradation products. True or false?True.
How is disseminated intravascular coagulation treated?The underlying condition is treated and this is often all that is necessary in patients who are not bleeding. Maintenance of blood volume and tissue perfusion is essential. Transfusions of platelet concentrates, FFP (fresh frozen plasma), cryoprecipitate, and red cell concentrates is indicated in patients who are bleeding.
How does the clinical picture of hyper-fibrinolysis differ from that of disseminated intravascular coagulation?It should be made clear that activation of fibrinolysis occurs in DIC as a secondary event in response to intravascular deposition of fibrin. The clinical picture is similar to DIC with widespread bleeding. Laboratory investigations are also similar with a prolonged PT, APTT and TT, a low fibrinogen level, and increased FDPs, although fragmented red cells and thrombocytopenia are not seen, since disseminated coagulation is not present.
How is hyper-fibrinolysis treated?If the diagnosis is certain, fibrinolytic inhibitors such as epsilon-aminocaproic acid (EACA) or tranexamic acid can be given.