Anaemia Flashcards
Blood components
Plasma = 55% Cells = 45%
Cells found in blood include erythrocytes, leukocytes and platelets
Erythrocytes
7 microns in diameter
Biconcave discs with good plasticity
Haemopoiesis
Haemopoiesis is the production of RBCs
It begins in the foetus in the yolk sac before moving to the liver and spleen
After birth, it occurs in the bone marrow
Erythrocyte differentiation
RBCs differentiate from the myeloid lineage
They develop into an erythroblast and then eventually an erythocyte
Erythropoiesis
Erythropoiesis is stimulated by erythropoietin, which is released from the liver
Iron, vitamin B12 and folic acid are also required
Anaemia
Anaemia is characterised by a haemoglobin level lower than the reference range and a reduction in red cell mass
Clinical features of anaemia
- Fatigue
- Headaches
- Faintness
- Tissue hypoxia
Lab investigation of anaemia
A blood film can show anisocytosis (cell size variation), poikilocytosis (cell shape variation) and anisochromasis (haemoglobinisation variation)
A reduced erythrocyte count can also be seen
Iron deficiency
The most common cause of anaemia
Cells will be microcytic and hypochromic
Causes = increased demand, blood loss, poor diet, malabsorption
Iron deficiency treatment
Oral iron supplements
Megaloblastic anaemia
Characterised by enlarged megaloblasts
Results in Howell-Jolly bodies
Causes = B12 deficiency, folate deficiency, DNA synthesis defects
Anaemia of chronic diseases
Anaemia can also occur as a complication of chronic diseases such as microbial infections of immune disorders
Chronic inflammation causes release of hepcidin which limits iron release and erythropoietin production
Treating anaemia of chronic diseases
Treating the underlying disease is the only cure
Patients may benefit from erythropoietin supplements
Aplastic anaemia
Hypocellularity of the bone marrow
Causes = inherited disease, suppression of pluripotent stem cells (due to chemotherapy)
Symptoms of aplastic anaemia
- Bruising
- Bleeding gums
- Epistaxis
- Mouth infections
Treatment of aplastic anaemia
Withdrawal of causative agent
Infection control
Bone marrow transplant
Sickle cell anaemia
Caused by a point mutation in the B-globin gene
The mutated haemoglobin is unstable and becomes crystalline leading to chronic haemolysis
Treatment of sickle cell anaemia
Supportive therapies such as folic acid supplements can be helpful
Antibiotics and vaccines are important to prevent infections
Thalassaemia
Caused by abnormalities in globin chain synthesis
Results in ineffective erythropoiesis leading to haemolysis
G6P dehydrogenase deficiency
Affects the rate-controlling step of the pentose-phosphate pathway
Silent until a trigger is encountered (e.g. oxidant drugs)
Leads to haemolysis
