Podcast
Questions and Answers
What is a common characteristic of reticulocytes in cases of anaemia due to haemorrhage or haemolysis?
What is a common characteristic of reticulocytes in cases of anaemia due to haemorrhage or haemolysis?
Which of the following conditions is associated with a low reticulocyte count?
Which of the following conditions is associated with a low reticulocyte count?
What kind of anaemia is characterized by small, hypochromic red blood cells due to a deficiency of iron?
What kind of anaemia is characterized by small, hypochromic red blood cells due to a deficiency of iron?
Which symptom is NOT typically associated with iron deficiency anaemia?
Which symptom is NOT typically associated with iron deficiency anaemia?
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How is anaemia classified based on red blood cell size and shape?
How is anaemia classified based on red blood cell size and shape?
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Which of the following substances is essential for proper red blood cell production and is often deficient in certain types of anaemia?
Which of the following substances is essential for proper red blood cell production and is often deficient in certain types of anaemia?
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What is a possible cause of acquired anaemia that leads to destruction of red blood cells?
What is a possible cause of acquired anaemia that leads to destruction of red blood cells?
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What characterizes the red blood cell (RBC) lifespan in patients with haemolytic anaemia?
What characterizes the red blood cell (RBC) lifespan in patients with haemolytic anaemia?
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Which condition would likely result in a normal reticulocyte count despite the presence of anaemia?
Which condition would likely result in a normal reticulocyte count despite the presence of anaemia?
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Which laboratory finding is indicative of immune haemolytic anaemia?
Which laboratory finding is indicative of immune haemolytic anaemia?
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What is the primary purpose of leukodepletion in blood component therapy?
What is the primary purpose of leukodepletion in blood component therapy?
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Which of the following best describes a common cause of drug-induced haemolytic anaemia?
Which of the following best describes a common cause of drug-induced haemolytic anaemia?
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Which of the following lab findings would most likely indicate a haemolytic anaemia?
Which of the following lab findings would most likely indicate a haemolytic anaemia?
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What is a potential consequence of bone marrow failure in the context of anaemia?
What is a potential consequence of bone marrow failure in the context of anaemia?
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What type of anemia is characterized by hyper-segmented neutrophils found on a peripheral smear?
What type of anemia is characterized by hyper-segmented neutrophils found on a peripheral smear?
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Which of the following statements is true regarding the mechanism of extravascular hemolysis?
Which of the following statements is true regarding the mechanism of extravascular hemolysis?
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What is a primary use of transfusing red blood cells?
What is a primary use of transfusing red blood cells?
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Which condition is NOT treated with fresh frozen plasma?
Which condition is NOT treated with fresh frozen plasma?
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Which antigen is essential for compatibility in red blood cell transfusions?
Which antigen is essential for compatibility in red blood cell transfusions?
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What type of antibodies do individuals with blood group O naturally form?
What type of antibodies do individuals with blood group O naturally form?
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How is the blood group determined genetically?
How is the blood group determined genetically?
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In which situation is cryoprecipitate particularly useful?
In which situation is cryoprecipitate particularly useful?
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Which of the following statements is false regarding immune antibodies in blood types?
Which of the following statements is false regarding immune antibodies in blood types?
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Which condition does NOT lead to an effective production of platelets?
Which condition does NOT lead to an effective production of platelets?
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Study Notes
Haematology: RBC Disorders and Clinical Haematology
- This presentation covers red blood cell (RBC) disorders and clinical haematology.
- Dr G O'Connor, [email protected], is the presenter.
Red Blood Cells
- RBCs are designed to carry oxygen from the lungs to body tissues.
- Their cytoplasm contains haemoglobin, an oxygen-binding protein.
- Their small diameter (7–8 µm) and biconcave shape maximize surface-to-volume ratio, aiding oxygen exchange.
- The diameter of a RBC is 7.2 µm.
Haemoglobin
- Adult haemoglobin is a tetramer of 2β₂.
- Each chain carries an iron-containing haem group.
- Haemoglobin reversibly binds oxygen to form oxyhaemoglobin.
- Oxygen binding to one haem group increases oxygen affinity for other sites (cooperative binding).
Measuring Haematological Parameters
- Full blood count (FBC) assesses various RBC characteristics.
- Parameters include red blood cell count, mean cell volume, packed cell volume, haemoglobin, mean cell haemoglobin, mean cell haemoglobin concentration, and red cell distribution width.
Blood Film
- Blood films are stained microscopic examinations of blood samples, displaying various blood cell types, including RBCs.
- Typical blood film images are provided in the presentation.
- Different blood cells (e.g., platelets, lymphocytes, monocytes, eosinophils, neutrophils, basophils) are identifiable on the smear.
Red Blood Cell Disorders
- Anaemia is the most prevalent blood disorder globally.
- Anaemia results from reduced red blood cell haemoglobin concentration.
- Symptoms can range from mild (asymptomatic) to severe, reflecting reduced oxygen delivery.
- Common symptoms include fatigue, lethargy, breathlessness, fainting, pallor, palpitations, worsening angina, loss of appetite, and weight loss.
- Assessing the lower eyelid conjunctiva (appears pale pink or white in anaemia) helps diagnose anaemia.
Basis for Classification of Anaemia
- Categorization is primarily based on RBC size and shape.
- Microcytic anaemia involves small RBCs, while macrocytic anaemia involves large RBCs.
- Poikilocytosis (nonuniform cell shapes) and anisocytosis (nonuniform cell sizes) further aid in classifying erythrocyte disorders.
- Based on cell morphology, different types of anaemia (e.g., microcytic, macrocytic, normocytic) are diagnosed.
Acquired or Inherited Anaemia
- Anaemia arises due to significant blood loss, reduced red cell production, or excessive red cell destruction.
- Acquired causes include iron, vitamin B12, or folate deficiency, blood loss, chronic disease, immune reactions, bone marrow infiltration (e.g., leukemia, lymphoma), and aplastic anaemia.
- Inherited causes include haemoglobinopathies (e.g., thalassemia, sickle cell disease), red blood cell membrane defects, and red blood cell enzyme defects.
Anaemia: RBC MCV
- MCV (<80 fL) represents microcytic anaemia (small red blood cells).
- MCV (> 96 fL) represents macrocytic anaemia (large red blood cells).
- Normal MCV represents normocytic anaemia (normal-sized red blood cells).
Reticulocyte Count
- Reticulocyte count helps evaluate red blood cell production.
- Elevated reticulocyte counts indicate increased red blood cell production in response to conditions like haemorrhage or haemolysis.
- Decreased reticulocyte count suggests a problem in red blood cell production.
Microcytic Anaemia: Iron Deficiency Anaemia
- Iron deficiency anaemia is a common cause of microcytic anaemia.
- Low iron levels result in reduced haemoglobin synthesis.
- Symptoms include typical anaemia symptoms; further symptoms involving mucous membranes, nails, and mouth are more specific to this type of anaemia.
Causes of Iron Deficiency
- Insufficient iron intake (poor diet).
- Increased iron requirements (growth spurts, pregnancy).
- Malabsorption (gastrointestinal issues).
Laboratory Findings of Iron Deficiency Anaemia
- Low haemoglobin, low MCV, low mean corpuscular haemoglobin.
- Blood film shows microcytic, hypochromic cells, pencil cells, and target cells.
Biochemistry of Iron Deficiency Anaemia
- Serum iron, transferrin, and total iron-binding capacity (TIBC) are examined.
- Serum ferritin is often reduced in iron deficiency.
- Reduced serum ferritin and elevated TIBC directly suggest low iron levels, with accompanying inflammation potentially masking this result.
Latent Iron Deficiency
- Latent iron deficiency involves reduced storage iron before overt anaemia.
RBC Antigens
- Transfusion of red blood cells requires compatibility between donor and recipient.
- ABO blood group antigens and Rhesus D antigen are critical.
ABO Blood Groups
- ABO blood group antigens are carbohydrates.
- Individuals possess antibodies against antigens they don't have (Landsteiner's rule).
- ABO incompatibility can cause serious reactions during transfusions.
Rhesus Grouping
- Five primary Rh antigens — D, C, c, E, and e — exist.
- D is the most significant for clinical purposes.
- Anti-D antibodies arise from previous exposures or incompatibility and can cause complications.
- Rhesus incompatibility can result in haemolytic disease in the newborn.
Haemolytic Anaemia
- Increased red blood cell destruction characterizes immune haemolytic anaemia.
- Underlying causes include autoantibodies or complement attacking red blood cells.
- A variety of medications, such as penicillin, quinidine, and methyldopa, can induce drug-induced haemolytic anaemia.
Other Considerations
- Reduced erythropoietin (EPO) production due to renal disease or bone marrow failure can lead to anaemia.
- Myelodysplastic syndromes (MDS) lead to immature blood cells failing to develop fully.
Blood Products
- Individual blood components are generally preferred over whole blood.
- Processing removes white blood cells (leukodepletion) to minimize immune reactions.
Blood Component Uses
- Red blood cells treat hypovolemia and severe anaemia.
- Fresh frozen plasma provides coagulation proteins.
- Cryoprecipitate contains high fibrinogen levels and is used for disseminated intravascular coagulation (DIC) or specific fibrinogen deficiency.
- Platelets treat bleeding related to thrombocytopenia.
Transfusion Reactions
- Various adverse reactions can occur during transfusions, including acute haemolytic reactions, febrile non-haemolytic reactions, allergic reactions (sometimes with anaphylaxis), and transfusion-related acute lung injury (TRALI).
- Delayed reactions such as delayed haemolytic reactions, graft-versus-host disease, and post-transfusion purpura are also potential complications.
- Infections like bacterial, viral (hepatitis B, C, and HIV), and prion diseases are possible but rare risks.
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