14 Blood cell abnormalities Flashcards
What is anaemia?
A reduction in the amount of haemoglobin in a given volume of blood (reduced Hb)
What (apart from Hb) is reduced in anaemia?
- RBC
- Hct (hematocrit - percentage volume of RBCs)
- PCV (packed cell volume)
What normally causes anaemia?
A reduction of the absolute amount of haemoglobin in the blood stream
Why can an increase in plasma volume not persist in healthy individuals?
The excess fluid is excreted (urine) and the plasma volumes are brought back to normal
What are the 4 mechanisms of anaemia?
- Reduced production of RBCs/haemoglobin in bone marrow
- Loss of blood from the body
- Reduced survival of RBCs in circulation
- Pooling of RBCs in a very large spleen
What are the probable causes of reduced synthesis of haemoglobin in the bone marrow?
Conditions causing
- Reduced synthesis of haem
- Reduced synthesis of globin
Namet wo causes of reduced synthesis of haem
- Iron deficiency
- Anaemia of chronic disease (chronic inflammation, Fe trapped in macrophages)
(lead?)
What is the name of a condition where there is an inherited defect leading to reduced globin production?
Thalassaemia
What is the main way of determining the cause of anaemia?
Classification on the basis of cell size
What is a microcyte?
A red cell smaller than normal
What is a normocyte?
A normal red cell (size + Hb)
What is a macrocyte?
A red cell larger than normal
What does hypochromic mean?
A red cell with less colour than normal (less Hb)
What does normochromic mean?
Concentration of Hb within cells is normal
Are microcytes typically hypochromic or normochromic?
Hypochromic
What two types of cells are normochromic?
- Normocytes
- Macrocytes
What are some common causes of microcytic anaemia?
- Defect in haem synthesis
- Defect in globin synthesis (thalassaemia)
What are the two types of thalassaemia?
α and β thalassaemia
- Defect in alpha chain synthesis
- Defect in beta chain synthesis
What are the causes of iron deficiency?
- Increased blood loss (commonest)
- Insufficient intake
- Increased requirement
What are some causes of increased blood loss?
- Hookworm
- Menstrual (menorrhagia)
What are some causes of insufficient intake?
- Dietary e.g. vegetarians
- Malabsorption (coeliac disease, H pylori gastritis)
What are the causes of increased requirements?
- Physiological e.g. during pregnancy, infancy
Why does macrocytic anaemia occur?
- Abnormal haemopoiesis –> red cell precursors continue to produce Hb and proteins but fail to divide normally
What are the common causes of macrocytic anaemia?
- Megaloblastic erythropoiesis
- Liver diseases/ethanol toxicity
- Major blood loss (increased reticulocytes)
- Haemolytic anaemia (increased reticulocytes)
