Haematology 2

oelomar's version from 2018-04-01 16:39


Question Answer
Where in the body is folic acid absorbed?Duodenum/early jejunum.
What are the clinical features of folate deficiency?Patients with folate deficiency may be asymptomatic or present with symptoms of anaemia or of the underlying cause. Anaemia is a late finding in folate deficiency, and the term given for this medical condition is folate deficiency anaemia.
What is the link between “hypersegmented polymorphs” and folate deficiency anaemia?Hypersegmented neutrophils (polymorphs) have been classically thought to be characteristic of megaloblastic anaemias, often caused by folate or vitamin B12 deficiencies. (However, in seeming contradiction to this, several studies have strongly associated neutrophil hypersegmentation with iron deficiency anaemia).
How is folate deficiency treated?Folate deficiency can be corrected by giving 5mg of folic acid daily; the same haematological response occurs as seen after treatment of vitamin B12 deficiency. Treatment should be given for about 4 months to replace body stores. Any underlying causes (e.g. coeliac disease) should be treated.
How does one distinguish between macrocytic anaemia caused by liver damage or folate deficiency?Liver damage = round macrocytes; B12/folate deficiency = oval-shaped macrocytes.


Question Answer
What is the most common cause of non-megaloblastic macrocytic anaemias?Alcohol excess. Pregnancy is also a common cause.
People who have inherited sickle cell anaemia may experience attacks of pain (“sickle cell crisis”). What can precipitate an attack?Infection, dehydration, cold, acidosis or hypoxia.
Most people affected by sickle-cell disease are of African origin. True or false?True.
Dactylitis is one of the clinical findings in sickle cell anaemia. What is this?Acute pain in the hands and feet owing to vaso-occlusion of the small vessels.
Acute chest syndrome is one of the clinical findings in sickle cell anaemia. What is this and what are its signs and symptoms?A vaso-occlusive crisis of the pulmonary vasculature commonly seen in patients with sickle cell anaemia, and is a common cause of death in sickle cell disease patients. This condition commonly manifests with pulmonary infiltrate on a chest x-ray. It can be associated with one or more symptoms including fever, cough, excruciating pain, sputum production, shortness of breath, or low oxygen levels.
How can bones be affected by sickle cell disease?Bones are a common site for vaso-occlusive episodes, leading to chronic infarcts. Avascular necrosis of hips, shoulders, compression of vertebrae, and shortening of bones in the hands and feet occur.


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Can people with sickle cell disease develop ulcers?Yes. Legs ulcers occur spontaneously (vaso-occlusive episodes) or following trauma and are usually over the medial or lateral malleoli. They often become infected and are quite resistant to treatment.
Can people with sickle cell disease develop cardiac problems?Yes. Cardiac problems occur, with cardiomegaly, arrhythmias, and iron overload cardiomyopathy. Myocardial infarctions occur due to thrombotic episodes which are not secondary to atheroma.
Can people with sickle cell disease develop neurological problems?Yes. Neurological complications occur in 25% of patients, with transient ischaemic attacks, fits, cerebral infarction, cerebral haemorrhage, and coma. Strokes occur in about 11% of patients under 20 years of age.
Can patients with sickle cell disease develop eye problems?Yes. Background retinopathy, proliferative retinopathy, vitreous haemorrhages, and retinal detachments all occur. Regular yearly eye checks are required.
Can male patients with sickle cell disease develop priapism?Yes. An unwanted painful erection occurs from vaso-occlusion and can be recurrent. This may result in impotence. Treatment is with an alpha-adrenergic blocking drug, analgesia, and hydration.
What are the potential implications of sickle cell disease in pregnancy?Impaired placental blood flow causes spontaneous abortion, intrauterine growth retardation, preeclampsia and foetal death. Painful episodes, infections, and severe anaemia occur in the mother.
Haemoglobin electrophoresis is always needed to confirm the diagnosis of sickle cell anaemia. What will it show?There is no adult haemoglobin (HbA), 80-95% sickle cell haemoglobin (HbSS), and 2-20% foetal haemoglobin (HbF).
How is sickle cell anaemia treated?Infections are treated and pain is managed. A transfusion can be given when needed, such as in acute chest syndrome. Bone marrow transplant can be curative. Hydroxycarbamide (hydroxyurea) is the first drug which has been widely used as therapy for sickle anaemia.
What is “sickle cell trait” and what are its symptoms?Sickle cell trait describes a condition in which a person has one abnormal allele of the haemoglobin beta gene (is heterozygous), but does not display the severe symptoms of sickle cell disease that occur in a person who has two copies of that allele (is homozygous). These individuals have no symptoms unless extreme circumstances cause anoxia, such as flying in a non-pressurised aircraft.


Question Answer
What is aplastic anaemia?Aplastic anaemia is defined as pancytopenia with hypocellularity (aplasia) of the bone marrow; there are no leukaemic, cancerous or other abnormal cells in the peripheral blood or bone marrow.
What are the causes of aplastic anaemia?It can be idiopathic, congenital, or drug-mediated.
What are the clinical features of aplastic anaemia?The clinical manifestations of marrow failure from any cause are anaemia, bleeding and infection. Bleeding is often the predominant initial presentation of aplastic anaemia with bruising with minimal trauma or blood blisters in the mouth. Physical findings include ecchymoses, bleeding gums, and nosebleeds.
How is aplastic anaemia treated?The main danger is infection and stringent measures should be undertaken to avoid this. Any suspicion of infection in a severely neutropenic patient should lead to immediate institution of broad-spectrum parenteral antibiotics. Bone marrow transplantation is the treatment of choice for some patients. Immunosuppressive therapy can also be given, the standard of which is antithymocyte globulin (ATG) and cyclosporine.
With regards to haemolytic anaemia, what is meant by “intravascular” and extravascular”?Intravascular haemolysis refers to red cells lysing in the blood vessels. Extravascular haemolysis refers to red cells lysing outside the blood vessels e.g. by macrophages in the liver or spleen.
What are the clinical features of extravascular haemolysis (in haemolytic anaemia)?Anaemia, splenomegaly, jaundice.
Can splenomegaly help in treating patients with extravascular haemolysis?Yes. Much of the pathologic destruction of red cells occurs in the spleen, individuals with extravascular haemolysis often benefit from splenectomy.
What are the clinical features of intravascular haemolysis (in haemolytic anaemia)?Anaemia, haemoglobinaemia leading to haemoglobinuria leading to haemosiderinuria (brown urine – because as haptoglobin is depleted, free haemoglobin oxidises to methaemoglobin which is brown in colour), jaundice. Splenomegaly is not seen.
What is haptoglobin, and how do levels change in haemolytic anaemias?Haptoglobin is a protein that binds free haemoglobin and prevents its excretion in the urine. In haemolytic anaemia (both intravascular and extravascular), levels of haptoglobin are decreased (they are decreased in extravascular haemolysis because some haemoglobin can escape from phagocytes).
Chronic intravascular haemolysis leads to the formation of pigment gallstones. True or false?True.


Question Answer
What test can be used to diagnose haemolytic anaemia?Direct Coombs test.
Name some intrinsic haemolytic normocytic anaemias.Hereditary spherocytosis, G6PD deficiency, pyruvate kinase deficiency, paroxysmal nocturnal haemoglobinuria.
What is hereditary spherocytosis?An autosomal dominant defect of the red blood cell cytoskeleton in which the normal biconcave disc shape is replaced by a sphere-shaped red blood cell which loses parts of its cell membrane as they pass through the spleen. RBC survival is reduced as they are destroyed by the spleen.
How does hereditary spherocytosis present?Failure to thrive, jaundice, gallstones, splenomegaly, aplastic crisis precipitated by parvovirus infection. The course of the disease may be interrupted by aplastic, haemolytic and megaloblastic crises.
How is hereditary spherocytosis diagnosed?Osmotic fragility test (spherocytes tolerate hypotonic solutions less well). Direct antiglobulin (Coombs) test is negative in hereditary spherocytosis, virtually ruling out autoimmune haemolytic anaemia where spherocytes are also commonly present. Howell-Jolly bodies are present after splenectomy.
What will a blood film show in people with hereditary spherocytosis?Spherocytes (round, lack of central pallor).
What is the osmotic fragility test?Erythrocyte fragility refers to the propensity/tendency of RBCs to haemolyse under stress. Osmotic fragility refers to the degree of haemolysis that occurs when a sample of RBCs are subjected to osmotic stress by being placed in a hypotonic solution. This test can be used to aid in the diagnosis of disease associated with RBC membrane abnormalities. Some diseases linked to increased osmotic fragility include hereditary spherocytosis and hypernatraemia, whilst some linked to decreased osmotic fragility include thalassaemia, iron-deficiency anaemia, hyponatraemia, polycythaemia vera, and chronic liver disease.
What is the treatment for hereditary spherocytosis?Splenectomy.
What is hereditary elliptocytosis?An inherited blood disorder in which an abnormally large number of the patient's erythrocytes (i.e. red blood cells) are elliptical rather than the typical biconcave disc shape. It is clinically similar to hereditary spherocytosis but milder. Only a minority of patients have anaemia.
What is hereditary stomatocytosis?Stomatocytes are red cells in which the pale central area appears slit-like. It can be genetic or due to excess alcohol intake. Hereditary stomatocytosis describes a number of inherited autosomal dominant human conditions which affect the red blood cell, in which the membrane or outer coating of the cell 'leaks' sodium and potassium ions.
Splenectomy is contraindicated in hereditary stomatocytosis. True or false?True. Splenectomy may result in fatal thromboembolic events, and a correct diagnosis is therefore crucial.


Question Answer
What is G6PD deficiency?Glucose-6-phosphate dehydrogenase deficiency is an x-linked recessive genetic condition that predisposes to haemolysis and resultant jaundice in response to a number of triggers, such as certain foods, illness, or medication. It is particularly common in people of Mediterranean and African origin. The condition is characterised by abnormally low levels of glucose-6-phosphate dehydrogenase, an enzyme that is especially important in the red blood cell.
What are the clinical features of G6PD deficiency?The clinical features are due to rapid intravascular haemolysis with symptoms of anaemia, jaundice and haemoglobinuria.
What will a blood film show in people with G6PD deficiency?The blood count is normal between attacks. During an attack, the blood film may show irregularly contracted cells, Heinz bodies, “bite cells”, “blister cells”, and reticulocytosis.
How is G6PD deficiency treated?There is no specific treatment, other than avoiding known triggers e.g. offending drugs should be stopped, and underlying infection should be treated. A blood-transfusion may be life-saving.
What is pyruvate kinase deficiency?Pyruvate kinase deficiency is an inherited lack of the enzyme pyruvate kinase, which is used by red blood cells. Without this enzyme, red blood cells break down too easily, resulting in low levels of these cells (haemolytic anaemia), and splenomegaly.
What will a blood film show in people with pyruvate kinase deficiency?Distorted (“prickle”) cells and reticulocytosis.
How is pyruvate kinase deficiency managed?Blood transfusions may be necessary during infections and pregnancy. Splenectomy may improve the clinical condition and is usually advised for patients requiring frequent transfusions.


Question Answer
Usually transfusions are saved for cases of acute anaemia where haemoglobin is <7g/dl. True or false?True
When are blood transfusions indicated in heart failure patients?When there is also severe anaemia.
In heart failure patients, how are blood transfusions administered?Give packed cell slowly with furosemide.
What are the different blood transfusion reactions that can occur?Allergic reactions, anaphylactic reactions, febrile non-haemolytic reactions, acute haemolytic transfusion reactions.
What is a febrile non-haemolytic reaction that can occur post-blood transfusion?A type of transfusion reaction that is associated with fever but not directly with haemolysis. It is most commonly caused by antibodies directed against donor leukocytes and HLA (human leukocyte antigen) antigens. It is a type II hypersensitivity reaction.
What is an acute haemolytic transfusion reaction?A type of transfusion reaction that is associated with haemolysis. This can be intravascular (due to ABO blood group incompatibility) or extravascular (host antibody reaction against foreign antigen on donor RBCs).
With regards to blood transfusions, what is a “TRALI”?This is a transfusion related acute lung injury. It is a serious blood transfusion complication characterised by the acute onset of non-cardiogenic pulmonary oedema. It is due to the presence of leukocyte antibodies in transfused plasma.