Anaemia Flashcards
What is anaemia?
reduction in the amount of haemoglobin in a given volume of blood
–> los Hb often also low RBC and Hct/PCV
What is the difference between absolute and relative anaemia?
Absoulute: absolute amount of anaemia in the blood stream is reduced
Relative: plasma volume is increased –> this could not persist in a healthy individual
–> Normally anaemia is absolute
What is the difference between the mechanism and the cause of anaemia?
- The mechanism of the anaemia might be reduced synthesis of haemoglobin in the bone marrow
- The cause of this could be either a condition causing reduced synthesis of haem or one causing reduced synthesis of globin
What is microcytic anaemia?
What are common causes?
Common causes of a microcytic anaemia
-
Defect in haem synthesis
- •Iron deficiency
- •Anaemia of chronic disease
-
Defect in globin synthesis (thalassaemia)
- •Defect in α chain synthesis (α thalassaemia)
- •Defect in β chain synthesis (β thalassaemia)
What is thalassaemia?
What does it often result in?
Defect in globin synthesis (thalassaemia)
- •Defect in α chain synthesis (α thalassaemia)
- •Defect in β chain synthesis (β thalassaemia)
– >often resulting in microcytic anaemia
What is noromocytic anaemia?
What might be the causes?
Anaemia with normal MCV
Might be due to
- Recent Blood loss
- oesophageal varicies
- peptic ulcer
- trauma
- Failure to produce red cells
- renal failure (reduced epo?)
- early stage of anaemia or chrionic disease
- bone marrow supression of failure
- bone marrow infiltration
- Hypersplenism e.g. due to portal cirrhosis
What is a megaloblast?
What are possible causes?
What can megaloblast formation result in?
A red cell precursor, larger than normal because
- of a delay in maturation of the nucleus while the cytoplasm continues to mature and the cell continues to grow
- Normally due to lack of Vit B12 and Folic acid
- •Use of drugs interfering with DNA synthesis or
- Liver disease and ethanol toxicity
–> can result in macrocytic anaemia, often oval + teardrop shaped + hyersegmentation of neutrophil nucleus
What is macrocytic anaemia?
What might be the causes?
Anaemia with increased MCV might be due to
-
Megaloblastic erythropoesis
- B12/folic acid deficiency
- drugs (interfering with DNA)
- Liver disease /ethanol toxicity
-
Premature release of Reticulocytes in blood
- are bigger than mature erythrocytes
- Due to
- Recent major blood loss with adequate iron stores
- Haemolytic anaemia
In which ways can you classify haemolytic anaemia?
-
Intrinsic vs Extrinsic
- Intrinsic: abnormality is within the red blood cell
- Extrinsic: extrinsic factors acting on normal erythrocyte
-
Inhierited vs aquired
- Inherited (genetic): abnormalities are within cell membrane/ haemoglobin, enzymes in cell
- Aquired: damage to the cell via e.g. micro-organisms/ chemicals etc
-
Intravascular vs Extravascular
- Intravascular: very acute damage to cell
- Extravascular: defective cells are removed by the spleen
- –> Normally a combination of intravascular + extravascular haemolosys
Which factors might lead you to suspect haemolytic anaemia?
- •Otherwise unexplained anaemia, which is normochromic and usually either normocytic or macrocytic
- •Evidence of morphologically abnormal red cells
- •Evidence of increased red cell breakdown
- •Evidence of increased bone marrow activity
What are evidences for an increased red cell break dwon where you might suspect a haemolytic anaemia
Jaundice (increased bilirubin)
Increased bown marrow output –> increased reticulocytes
Explain the mechanism of hereditary spherocytosis
Inherited membrane defect
->leads to removal of part of the membrane in spleen after cells enter the circulation –> Sperocytosis
This causes
- less flexible red cells
- removed by spleen –> extravascular haemolysis leading to jaundice and gallstones
- Increased output of bone marrow leading to polychromasia and reticulocytosis
What is the appropriate treatment for hereditary sperocytosis?
- Splenectomy (only effective treatment, only done in severe cases)
- Diet –> to prevent 2nd. folic acid deficiency
Explain the patophysiology and treatment of Glucose-6-phospate dehydrogenase deficiency
Causes severe intravascular haemolysis because of denauturation of haemoglobin (loss of ürotection from oxidatns)
Leading to
- irregularly contracted cells
- Heinz bodies
Treatment
- after acute haemolysis : blood transfustion
- Prevention is important (e.g. avoid oxidants in diet)
Explain the pathophysiology of Autoimmune haemolytic anaemia
It is a aquired haemolitiy anaemia that causes damage to the cell membrane
- Antibodies bind to antigens
- This complex is removed together with part of the membrane in spleen
- Leading to spreocytosis
- Resulting in Removal of cells in spleen
- Triggering an increased bone marrow output –> Presence of Reticulocytes
What is the role of B12 and folate?
They are cofactors for DNA synthesis
(methyldonor needed for enzyme methyltransferase)
- homocysteine to methionin
- methyl-THF to tetrahydrofolate (THF)
