Anaemia

Liam Musselbrook
Flashcards by Liam Musselbrook, updated more than 1 year ago
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Medicine (Haematology) Flashcards on Anaemia, created by Liam Musselbrook on 10/24/2017.
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Define anaemia - Decreased haemoglobin in the blood such that there is inadequate oxygen delivery to tissues - Hb <135g/L in men - Hb <115 in women
How can anaemia present? - Asymptomatic: a slowly falling Hb allows for haemodynamic compensation - Non-specific: fatigue, weakness, headaches - CV: dyspnoea on exertion, angina, intermittent claudication, palpitations
What general signs can be seen in a patient with anaemia? - Pallor - Tachycardia - Systolic flow murmur - Signs of heart failure
Give examples of specific signs that suggest certain types of anaemia - Koilonychia: IDA - Jaundice: haemolytic anaemia - Leg ulcers: sickle cell disease - Bone marrow expansion leading to abnormal facial structures/pathological fractures: thalassemia (rare)
Discuss anaemia and transfusion - Generally not indicated if there is no acute bleed & pt is not symptomatic - If anaemia is severe and requires transfusion, beware of associated HF - Transfusion should be given very slowly alongside furosemide
What are MCV and MCH? - MCV = size of each RBC - MCH = amount of haemoglobin in each red blood cell
What are the causes of microcytic anaemia (Low MCV, <80fl)? - Iron deficiency anaemia (IDA): blood loss until proven otherwise - Thalassemia - Lead poisoning - Sideroblastic anaemia (rare)
What are the causes of normocytic anaemia (normal MCV)? - Acute blood loss - Anaemia of chronic disease - Renal anaemia - Haemolytic anaemias (can be macrocytic due to reticulocytosis - Marrow failure - Pregnancy - Connective tissue diseases - Diamorphic blood film (combined micro/macrocytic processes)
What are the causes of macrocytic anaemia (high MCV, >96fl) - B12 deficiency (pernicious anaemia/Crohn's) - Folate deficiency (coeliac disease) - Alcohol excess (or severe liver disease) - Myelodysplastic syndromes - Severe hypothyroidism (myxoedema, can be normocytic)
What investigations would help you determine the aetiology of a microcytic anaemia? - FBC - Iron studies: serum iron, serum ferritin, total iron binding capacity, serum soluble transferrin receptors - Blood film: microcytic anaemia generally also hypochromic (pale on blood film, represents low MCH), may also show sideroblasts/signs of thalassemia
What signs can indicate IDA? - Koilonychia - Angular stomatitis - Brittle nails/hair
How does IDA develop and what is the 'latent iron deficiency' period? - Inadequate iron for haemoglobin synthesis - 'Latent iron deficiency' period is when normal Hb is maintained despite the iron deficiency
What are the different causes of IDA? - Blood loss: hookworm most common worldwide, heavy menstruation or GI bleeds the most common in the UK - ↓ absorption e.g. coeliacs, pts on antacids - ↑ demand: growth & pregnancy - Inadequate intake: rare in developed world, premature infants/prolonged breastfeeding most at risk
How is IDA diagnosed? - Blood film: microcytic, hypochromic cells with poikilocytosis (shape variation) and anisocytosis (size variation) - ↓ serum iron - ↑ total iron binding capacity - ↓ serum ferritin - ↑ soluble transferrin receptor
What further investigations might you do for a patient with IDA? - If good Hx of menorrhagia (ask about no. of sanitary items used), start oral iron, with only further investigation necessary being coeliac serology - Without obvious cause: check coeliac serology and refer for GI investigation - Stool microscopy if recent foreign travel
Discuss the management of IDA - Address underlying cause - Oral ferrous sulphate 200mg t.d.s, commence before results of Ix - Advise ↑ dietary intake of dark green vegetables, fortified bread/cereals, lean red meat and prunes/raisins - If ferrous sulphate is not tolerated, consider switch to ferrous gluconate - Monitor for improvement after 1 month - Continue Tx for 3 months after blood parameters return to normal
What is the 'Rule of 10's'? - The maximum rise in Hb concentration in 1 week is 10g/L - If more han 10g/L decline is seen over a week, then blood is being lost - When transfusing, 1 bag will ↑ HB concentration by 10g/L
Give common side effects of ferrous sulphate and how can they be ameliorated? - GI-related: cramping, bloating, nausea, vomiting, constipation and black stools - Adverse effects can be decreased if taken with meals, offering laxatives or dose reduction
Anaemia of chronic disease is a top differential for IDA, how can it be differentiated using investigations? - Serum iron will be decreased (same as IDA) - TIBC decreased (increased in IDA) - Soluble transferrin receptor is normal (increased in IDA) - Ferritin will be raised (decreased in IDA)
What is Patterson-Brown (Plummer-Vinson) syndrome and how is it treated? - Rare - Characterised by dysphagia, odynophagia, IDA, glossitis, chelitis and oesophageal webs - Generally occurs in post-menopausal women - Tx: iron supplementation and mechanical widening of oesophagus
What is thalassemia? - Genetic disorders of Hb synthesis - Common in the Middle/Far East - Caused by deficient alpha or beta chains, thus resulting in α- and β-thalassemia (split into minor (trait) and major (Cooley's anaemia))
Discuss β-thalassemia minor: presentation, haemoglobin - Carrier state - Usually asymptomatic and gives a mild microcytic anaemia that may worsen in pregnancy - Often confused with IDA - HbA2 is raised, with slightly raised HbF also
Discuss β-thalassemia major (Cooley's anaemia): genetic abnormality, presentation, extra features, survival, blood film and management - Abnormality in both globin genes - Presents within first year with severe anaemia, hepatosplenomegaly and FTT - Extramedullary haematopoiesis results in facial deformities - Survival is possible due to HbF - Blood films show hypochromic microcytic cells, also target cells and nucleated RBCs - Manage with lifelong blood transfusions
Discuss α-thalassemia: different genetics and their manifestations - Bart's hydrops: deletion of all 4 α-globin genes > HbBarts (γ4), death in utero - Deletion of 3 genes: moderate microcytic anaemia with features of haemolysis - Deletion of 2: asymptomatic carrier state with reduced MCV - Deletion of 1: clinically normal
What is sideroblastic anaemia and how is it caused? - Bone marrow produces ringed 'sideroblasts' rather than erythrocytes, which can be seen in the bone marrow - Can be a congenital disorder or, more commonly, acquired in myelodysplastic syndrome
Outline the approach to investigating a macrocytic anaemia - Blood film: hypersegmented neutrophils in B12/folate deficiency - LFTs/TFTs: raised bilirubin in B12/folate deficiency - Serum B12/folate - If B12 is low: > Anti-parietal cell Ab, anti-IF Ab > Schilling test - Bone marrow biopsy: megaloblasts suggest B12/folate deficiency
What is the mechanism by which B12/folate deficiency causes macrocytic anaemia? - Both involved in DNA synthesis - Malfunctioning DNA synthesis leads to failure to 'stop' erythrocyte development leading to very large cells, which eventually are trapped and destroyed in the reticuloendothelial system
Outline the physiological absorption of B12 - From animal: meat. eggs etc - To be absorbed, B12 must combine with intrinsic factor (IF) produced in the stomach (parietal cells). *In complete absence of IF, 2% of B12 can still be absorbed - B12 is absorbed in terminal ileum - Even in total malabsorption, body stores will last for 3 years
What are the different causes of B12 deficiency? - Chronic low dietary intake (vegans) - Impaired binding in the stomach: pernicious anaemia, congenital absence of IF, gastrectomy - Small bowel disease: resection, Crohn's/backwash ileitis in US, bacterial overgrowth *Pancreatitis, coeliac disease and metformin cause mild impairment but not enough to cause significant B12 deficiency
What is pernicious anaemia? - Autoimmune disease resulting in severe B12 deficiency - There are 3 types of autoantibodies which can contribute towards disease: > Autoantibodies against parietal cells > Blocking antibodies > Binding antibodies
Name a significant complication of B12 deficiency and describe how it presents - Subacute combined degeneration of the cord - Simultaneous posterior column (LMN) and CST (UMN) loss due to B12 deficiency, gives both LMN & UMN signs - Initial peripheral neuropathy - Classic triad: extensor plantars, brisk knee jerks but absent ankle jerks - Tone & power usually normal, gait may be ataxic
Give causes of folate deficiency - Poor nutritional intake: poor diet, alcohol excess, anorexia - Malabsorption: coeliac disease - Anti-folate drugs: trimethoprim, methotrexate, anti-convulsants - Excess physiological use: pregnancy, lactation, prematurity - Pathological use: excess erythrocyte production, malignancy, inflammatory disease
How is folate deficiency treated? - Folic acid 5mg/day PO for 4 months - Always with combined B12 unless known to have normal B12 level
Outline the approach to investigating a normocytic anaemia - Is there acute blood loss? - Is there underlying chronic disease? - Is it haemolytic? - Are other cell lines affected?
Discuss anaemia of chronic disease and its pathology - Normochromic or hypochromic - Rarely severe - Seen in chronic infection, malignancy, CKD and rheumatoid disorders - Pathology involves predominant WBC production in the bone marrow
Discuss bone marrow failure as a cause of anaemia - Hb, reticulocytes, WBC and platelets all equally low - Alterations on blood film, will require bone marrow biopsy - If there are no abnormal blasts in pancytopenic marrow, diagnosis = aplastic anaemia (idiopathic or drug induced) - Other causes apparant on marrow: haem malignancies, metastatic disease, myelofibrosis or myelodysplasia - Parvovirus can also cause cessation of marrow erythropoiesis
Where does extravascular haemolysis take place? Reticuloendothelial system of the liver, spleen and bone marrow
What is the normal lifespan of a RBC? 120 days
Give intrinsic causes of haemolytic anaemia - Haemoglobinopathies: sickle cell, thalassemia - Membranopathies: spherocytosis, eliptocytosis - Enzymeopathies: G6P deficiency
Give extrinsic causes of haemolytic anaemia - Autoimmune disease: warm or cold - Alloimmune disease: transfusion/transplant reaction, rhesus disease - Drug induced e.g. penicillins - Parasites: plasmodium etc - Microangiopathic haemolytic anaemias e.g. DIC
What standard investigations might help you diagnose haemolytic anaemia? - FBC: low Hb with ↑ MCV - LFTs: ↑ unconjugated bilirubin - Lipids: ↑ serum LDH (released from RBCs) - Reticulocyte count: >2% or 100x10^9/L suggests ↑ RBD production, will give ↑ MCV - Blood film
What different features might be picked up on a blood film of a random haemolytic anaemia, and to what conditions do they link to? - Hypochromic, microcytic cells: thalassemia - Sickle cells: sickle cell anaemia - Spherocytes: hereditary spherocytosis or autoimmune haemolytic anaemia - Eliptocytes: hereditary eliptocytosis - Heinz bodes/'bite' cells: G6PD deficiency - Schistocytes: microangiopathic haemolytic anaemia
What further tests might you do to pursue a diagnosis of a haemolytic anaemia? - Coomb's test: identifies RBCs coated with antibodies or complement, indicating immune cause of haemolysis - Hb electrophoresis: identify haemoglobinopathies - Enzyme assays - ↓ plasma haptoglobin and urinary haemosiderin present indicate intravascular haemolysis
What is sickle cell anaemia (SCA)? - Autosomal recessive disorder - Production of abnormal β-globulin - Results in production of HbS rather than HbA - Much more common in patients of African origin
What are the different genotypes of SCA? - HbSS (phenotype) - HbAS (trait): confers protection from malaria, rarely symptomatic but vaso-occlusive events may occur in hypoxia (e.g. flying or anaethesia)
Outline the pathogenesis of SCA - HbS polymerises when deoxygenated, causing RBCs to form 'sickle cells' - Sickle cells are fragile and haemolyse, and also block small vessels
How is SCA diagnosed? - Usually on the 'Guthrie' screening card - Sickle cells can be seen on the blood film - Hb electrophoresis can confirm the diagnosis and also distinguish variants
How does SCA normally present? - Often presents first few months of life, with anaemia developing as HbF levels fall, with acute haemolytic crises occurring causing bone infarcts and painful dactylitis - In adulthood, there is normally a chronic haemolytic anaemia but is well tolerated unless there is a crisis
What are the complications of SCA? - If untreated there is splenic infarction leading to hyposplenism, renal infarction to CKD, and cerebrovascular accidents - Bone necrosis - Chronic leg ulcers - Iron overload (if multiple transfusions) - Long term pulmonary damage
Outline the long-term management of SCA - Lifelong folate supplementation - Pneumococcal vaccination and prophylactic penicillin due to hypsplenism - Hydroxycarbamide (hydroxyurea) can help by increasing HbF production and is advised if there are frequent crises - Regular life-long transfusions (2-4 weekly), with iron chelators to prevent overload - Bone marrow transplantation is curative but limited by donor matches
What are the different types of crises in SCA? - Vaso-occlusive crises (painful crises) - Aplastic crises - Sequestration crises - Haemolytic crises (rare)
What happens in a vaso-occlusive crisis? - Occur due to microvascular occlusion - Often affect bone marrow leading to severe pain - Can be precipitated by cold, infection, dehydration or hypoxia - Other presentations: mesenteric ischaemia, cerebral infarctions or priapism
What happens in an aplastic crisis? - Due to parvovirus B19 - Causes a sudden reduction in marrow production, particularly RBCs - Usually self-limiting (<2 weeks), but transfusion may be required
What happens in a sequestration crisis? - Mainly affects children as spleen has not yet undergone atrophy - Pooling of blood in the spleen +/- liver, with organomegaly, severe anaemia and shock - Urgent transfusion required
Discuss the general management of a sickle cell crisis - A-E resus, high flow O2 and IV fluids - Strong analgesia within 30 mins - FBC, reticulocytes, cross-match - Screen for infection (culture, MSU, CXR) and treat early - Prophylactic enoxaparin - Give fully cross-matched blood transfusion if Hb or reticulocytes fall sharply - Exchange transfusion if rapidly deteriorating
Discuss G6PD deficiency: genetics and presentation - X-linked inheritance - More common in African and Mediterranean males (females have mild symptoms) - Mostly asymptomatic, but susceptible to oxidative crises - These attacks cause rapid anaemia and jaundice, may be precipitated by drugs (aspirin, sulphonamides), broad bean consumption or illness
Outline the diagnosis and treatment of G6PD - Heinz bodies, 'bite cells' and 'blister cells' seen on blood film - Proper diagnosis is made with enzyme assay 3 months after initial crisis - Tx: precipitant avoidance, plus transfusion if severe
Discuss pyruvate kinase (PK) deficiency - Autosomal recessive condition - ↓ ATP production shortens RBC lifespan - Homozygotes present with neonatal jaundice, and later chronic jaundice with hepatosplenomegaly - Diagnosis with enzyme assay - Often well tolerated, so no specific therapy needed
What is hereditary spherocytosis? - Autosomal dominant - Membrane defect leading to spherical RBCs - Less deformable, thus can become trapped in the spleen leading to haemolysis, splenomegaly and jaundice - Treated with folate - Splenectomy is curative, but reserved for severe disease
Discuss autoimmune haemolytic anaemia - Extravascular haemolysis and spherocytosis - Disease most commonly idiopathic but can be 2° to lymphoproliferative diseases or aother autoimmune disease - Classified according to optimal temperature that antibodies bind to RBCs
What is the difference between 'warm' and 'cold' autoimmune haemolytic anaemia? - Warm: IgG mediated, optimal binding at 37 degrees, treated with steroids or immunosuppressants +/- splenectomy - Cold: IgM mediated, optimal binding below 4 degrees, associated with Raynaud's, treated with cold avoidance +/- chlorambucil
Give different causes of microangiopathic anaemia (mechanical haemolysis due to physical trauma in the circulation) - Malignant HTN/ pre-eclampsia - HUS - Thrombotic thrombocytopenic purpura - Vasculitis (e.g. SLE) - DIC - Mechanical heart valves
Describe anaemia screening before surgery - <60g/L will require transfusion - <100g/L may require transfusion depending on cardiac risk and anticipated blood loss
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