Haemoglobinopathies And Anaemia Flashcards
What is the lifecycle of erythrocytes?
- Form in red bone marrow
- Circulate in blood stream for 120 days
- Aged erythrocytes are phagocytosed in liver and spleen
- Heme components are recycled
- Membrane proteins broken down into AAs to make new RBCs
Heme recycling involves converting heme minus iron to biliverdin, then bilirubin, and finally bile. Iron ions are transported by transferrin to ferritin in the liver.
What is the function of haptoglobin?
Binds to free hemoglobin, allows degrading enzymes to act, prevents kidney damage by hemoglobin, and regents loss of iron through kidneys
Levels are reduced in intra-vascular hemolysis.
Define anaemia.
Deficiency in number of erythrocytes or their hemoglobin content
Causes include hemorrhage, hemolysis, or insufficient production due to iron, B12, folate deficiency, or aplastic anemia.
What factors affect anaemia?
Age, gender, altitude, pregnancy
These factors can influence the prevalence and severity of anaemia.
What does mean cell volume (MCV) measure?
Average volume of RBCs
A key parameter in classifying types of anaemia.
What is mean cell hemoglobin (MCH)?
Average weight of hemoglobin in erythrocytes
Helps in assessing the hemoglobin content of red blood cells.
What does mean cell hemoglobin concentration (MCHC) indicate?
Average concentration of hemoglobin in erythrocytes
Useful for diagnosing different types of anaemia.
What is red cell distribution width (RDW)?
Measure of variability of erythrocyte size
Higher RDW can indicate certain types of anaemia.
Define haematocrit.
Relative volume of blood occupied by erythrocytes, normally 46%
A critical measurement in evaluating blood composition.
What are the classifications of anaemia based on MCV?
Microcytic (<76 fL), normocytic (76-96 fL), macrocytic (>96 fL)
These classifications help in diagnosing the underlying causes of anaemia.
What are common causes of microcytic anaemia?
- Iron deficiency
- Thalassemia
- Sideroblastic anaemia
Iron deficiency is the most common cause, often due to menorrhagia or gastrointestinal bleeding.
What characterizes microcytic anaemia?
RBCs can’t get sufficient hemoglobin to be released from bone marrow, resulting in extra cell divisions before release
This leads to smaller MCV.
What are common causes of normocytic anaemia?
- Hemorrhage
- Chronic disease (e.g., rheumatoid arthritis)
- Hemolytic anaemias
No specific signs are typically present.
What are common causes of macrocytic anaemia?
- B12 deficiency
- Folate deficiency
- Alcoholism
These can lead to megaloblastic anaemia.
What is the Schilling test used for?
To investigate B12 absorption
Helps differentiate between dietary deficiency and absorption issues.
What is reticulocyte count?
Count of immature blood cells
High count indicates bone marrow is responding well to anemia; low count indicates failure to respond.
What is sickle cell anaemia?
An autosomal recessive disorder characterized by abnormal hemoglobin S
It leads to distorted RBC shapes and can cause vaso-occlusive crises.
What are the symptoms of sickle cell crises?
- Vaso-occlusive crisis
- Aplastic crisis
- Hemolytic crisis
- Sequestration crisis
Each type of crisis has specific clinical features and management strategies.
What is thalassaemia?
A quantitative hemoglobinopathy leading to microcytic anaemia
It involves failure to produce either alpha or beta chains of hemoglobin.
What are common clinical features of hemolytic anaemia?
- Jaundice
- Increased bilirubin
- Increased reticulocytes
- Increased lactate dehydrogenase
- Decreased haptoglobins
- Increased urinary urobilinogen and positive urinary haemosiderin
These features arise from the breakdown of red blood cells.
What is aplastic anaemia?
Total bone marrow failure affecting all cell lineages
Causes include infection, drugs, and autoimmune diseases.
What is myelodysplastic syndrome (MDS)?
Malignant infiltration of bone marrow by immature blood cells leading to anemia, leukopenia, and thrombocytopenia
It may progress to acute myeloid leukaemia (AML).
What characterizes polycythaemia?
Hemoglobin greater than upper normal limit due to increase in erythrocytes or reduction in plasma volume
Primary causes include polycythemia vera; secondary causes are linked to increased erythropoietin.
What are the two main types of leukaemia?
- Acute
- Chronic
They are classified based on blast count in the bone marrow.
