11040265
Description
Flashcards by Liam Musselbrook, updated more than 1 year ago
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Created by Liam Musselbrook
about 7 years ago
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| Question | Answer |
| 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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