Anaemia and Polycythaemia Flashcards
What is anaemia?
A reduction in the amount of haemoglobin in a given volume of blood below what would be expected in comparison with a healthy subject of the same age and gender
Other than a reduction in the absolute amount of haemoglobin in the blood stream, what else could cause anaemia?
An increase in the plasma volume can decrease the haemoglobin concentration
Why would this type of anaemia only be transient in a healthy individual?
The excess fluid would be excreted in a healthy individual
Broadly speaking, state four mechanisms of anaemia.
Reduced production of red blood cells/haemoglobin in the bone marrow
Loss of blood from the body (haemorrhage)
Reduced survival of red blood cells (haemolytic)
Pooling of red blood cells in a very large spleen
For each type of anaemia, state whether they are usually hypochromic, normochromic or hyperchromic.
Microcytic – hypochromic
Normocytic – normochromic
Macrocytic - normochromic
State the common causes of microcytic anaemia.
Problem with Haem synthesis Iron deficiency Anaemic of chronic disease Problem with globin synthesis Alpha thalassemia Beta thalassemia
What mechanism usually causes macrocytic anaemia?
It usually results from abnormal haemopoiesis The cells fail to divide properly
What is megaloblastic erythropoiesis? Describe the appearance of a megaloblast.
Megaloblastic erythropoiesis refers to a delay in the maturation of the nucleus while the cytoplasm continued to mature and the cell continues to grow A megaloblast is an abnormal bone marrow erythroblast They are large and show nucleo-cytoplasmic dissociation
What is an alternative mechanism of macrocytosis?
You can get premature release of cells from the bone marrow Reticulocytes are about 20% larger than mature red cells so reticulocytosis would increase the MCV
State the two most common causes of megaloblastic anaemia.
B12 deficiency
Folate deficiency
State some other common causes of macrocytic anaemia.
Drugs that interfere with DNA synthesis (e.g. chemotherapy) Liver disease Ethanol toxicity Recent major blood loss with adequate iron stores (if you’ve lost blood, the bone marrow will start spitting out reticulocytes to compensate) Haemolytic anaemia (reticulocytosis due to the loss of red cells)`
State three mechanisms of normocytic normochromic anaemia.
Recent blood loss
Failure to produce red blood cells
Pooling of red blood cells in the spleen
State five causes of normocytic normochromic anaemia.
Peptic ulcer Oesophageal varices Trauma Failure of production of red blood cells Early stages of iron deficiency and ACD Renal failure Bone marrow failure Bone marrow infiltration Hypersplenism
Define haemolytic anaemia.
Anaemia resulting from shortened survival of red blood cells in the circulation
State two different classifications of haemolytic anaemia.
Haemolysis can be inherited (resulting from abnormalities of the cell membrane, haemoglobin or the enzymes in the red blood cell) It can be acquired usually resulting from extrinsic factors such as micro-organisms, chemicals or drugs Haemolytic anaemia can also be described as intravascular if there is very acute damage to the red cell It can also be classified as extravascular when the spleen removes defective red cells
State some inherited abnormalities that can cause haemolytic anaemia.
Abnormal red cell membrane
Abnormal haemoglobin
Defect in the glycolytic pathway
Defect in the enzymes of the pentose shuttle
State some acquired abnormalities that cause haemolytic anaemia.
Damage to the red cell membrane
Damage to the whole red cell Oxidant exposure
