Anaemia Flashcards
What is the WHO’s definition for anaemia?
- <130g Hb/L in men.
- <120g Hb/L in women.
- <110g Hb/L in pregnant women.
- Values at sea level only.
List 3 factors that might affect the normal / accepted ranges for anaemia.
1 - Pregnancy.
2 - Extremes of age.
3 - Different labs.
List the constituents of blood.
• Plasma:
- Plasma proteins.
- Electrolytes.
- Hormones.
- Nutrients.
• Buffy coat:
- Platelets.
- White cells.
• Red cells.
What proportion of the volume of blood does plasma represent?
What proportion of the volume of plasma is water?
- 55%.
- 91% of this is water.
List the subtypes of hemoglobin.
List their relative quantities in the blood.
1 - HbA (95%),
2 - HbA2 (3.5%).
3 - HbF (1%).
4 - HbS (pathological; >90% in sickle cell anaemia).
What protein chains / globins are found in HbA?
2x alpha and 2x beta.
What protein chains / globins are found in HbA2?
2x alpha and 2x delta.
What protein chains / globins are found in HbF?
2x alpha and 2x gamma.
What protein chains / globins are found in HbS (sickle cell haemoglobin)?
2x alpha and 2x mutated beta (beta s).
List four factors that increase haemoglobin’s affinity for oxygen.
1 - A decrease in temperature.
2 - A decrease in PCO2.
3 - A decrease in 2,3-DPG.
4 - An increase in pH.
Where in the body might the oxygen dissociation curve shift to the left?
In the placenta.
How does the oxygen dissociation curve for foetal haemoglobin differ from that of haemoglobin A?
The curve is shifted to the left (it has a higher affinity for oxygen than HbA).
How does the oxygen dissociation curve for sickle haemoglobin (HbS) and methaemoglobin differ from that of haemoglobin A?
The curve is shifted to the right (it has a lower affinity for oxygen than HbA).
What is methaemoglobin?
What might cause elevated levels of methaemoglobin?
- A form of haemoglobin that is unable to bind oxygen.
- Elevated levels may be caused by inheritable disorders or drug use.
Describe the mechanism by which 2,3-DPG improves oxygen delivery to tissues.
- When oxygen is released from haemoglobin, 2,3-DPG binds to the beta chains of haemoglobin.
- This results in a lower affinity of haemoglobin for oxygen and improves delivery of oxygen to tissues.
Define haematocrit.
The ratio of the volume of red blood cells to the total volume of blood.
List the values that can be found in a full blood count.
1 - Haematocrit.
2 - Packed cell volume.
3 - Red blood cell count.
4 - Mean cell volume.
5 - Mean corpuscular haemoglobin concentration.
6 - White blood cell count.
7 - Platelet count.
8 - Reticulocyte count.
What is the packed cell volume?
How is it found?
- The proportion of the volume of blood that is made up by cells.
- It is found by centrifugation.
List the physiological factors that determine the clinical features of anaemia.
1 - Hb level.
2 - Time taken for Hb levels to fall.
3 - Cause of anaemia.
4 - Concurrent changes in other factors e.g. 2,3-DPG.
List 7 signs of anaemia.
1 - Pallor.
2 - Tachycardia.
3 - Bounding pulse (the feeling of a racing pulse).
4 - Murmurs (whooshing sounds between beats caused by turbulence).
5 - Signs of heart failure.
6 - Koilonychia (thin, concave nails).
7 - Angular stomatitis (inflammation of the edges of the lips).
List 5 symptoms of anaemia.
1 - Fatigue.
2 - Breathlessness on exertion.
3 - Palpitations (abnormal fluttering of the heart).
4 - Audible pulse in arms.
5 - Angina.
List 3 types of causes of anaemia.
1 - Reduced production of Hb.
2 - Destruction of Hb (haemolysis / haemolytic anaemia).
3 - Poor function of Hb.
List 3 causes of anaemia that relate to a reduced production of Hb.
1 - Deficiencies in iron, B12 or folate.
2 - Bone marrow pathologies.
3 - Chronic diseases such as renal failure or chronic inflammatory conditions.
List 3 bone marrow pathologies that contribute to anaemia.
1 - Aplastic anaemia.
2 - Myelodysplasia.
3 - Myeloma.
Define aplastic anaemia.
An immune-mediated destruction of hematopoietic stem cells causing pancytopenia and an empty bone marrow.
Define myelodysplasia.
A group of cancers in which immature blood cells in the bone marrow do not mature.
Define myeloma.
A malignancy of B cells.
Define pancytopenia.
A deficiency of all three cellular components of the blood (red cells, white cells, and platelets).
List 3 causes of anaemia that relate to poor function of Hb.
1 - Membrane defects.
2 - Enzyme defects.
3 - Sickle cell anaemia.
List 2 membrane defects of erythrocytes that contribute to anaemia.
1 - Hereditary spherocytosis (spherical erythrocytes rather than biconcave).
2 - Hereditary elliptocytosis.
List 2 enzyme defects that contribute to anaemia.
1 - G6PD deficiency (favism).
2 - Pyruvate kinase deficiency.
Describe the process of vitamin B12 absorption.
1 - Vitamin B12 is liberated by HCl in the stomach.
2 - Parietal cells secrete haptocorrin, which binds to vitamin B12.
3 - Parietal cells secrete intrinsic factor, which replaces haptocorrin at the duodenum.
4 - The intrinsic factor-vitamin B12 complex is absorbed at the terminal ileum by enterocytes that express brush border receptors for intrinsic factor.
Describe the pathophysiology of hereditary spherocytosis.
A deficiency in ankyrin and / or beta-spectrin, which help maintain the cytoskeleton of erythrocytes.
What inheritance pattern is shown by hereditary spherocytosis?
Autosomal dominant.
List 3 treatments for hereditary spherocytosis.
1 - Folic acid supplements.
2 - Splenectomy.
3 - Transfusion.
Define thalassaemia.
- An inherited recessive condition characterized by a deficiency of alpha or beta chains in haemoglobin.
- Can be major (homozygous) or minor (heterozygous).
Define hypochromic.
Any type of anemia in which the red blood cells are paler than normal.
Define haemochromatosis.
Hemochromatosis is an iron overload syndrome associated with excessively absorbed iron that causes multiple organ dysfunctions.
Are thalassaemia patients transfusion dependent?
Only major (homozygous) patients are transfusion dependent.
Give an example of a sign of thalassaemia.
Splenomegaly.
What inheritance pattern is shown by sickle cell anaemia?
Autosomal recessive.
Describe the pathophysiology of sickle cell anaemia.
- Mutation of the beta chain / globin gene.
- Polymerisation of haemoglobin.
List 2 treatments of sickle cell anaemia.
1 - Transfusion.
2 - Hydroxycarbamide (raises the concentration of fetal haemoglobin in erythrocytes).
How does a G6PD deficiency affect erythrocytes?
- Mature red cells have no mitochondria, so can only produce ATP via glycolysis.
- G6PD is required for the production of ATP via glycolysis.
List 4 uses of ATP in erythrocytes.
1 - Maintenance of membrane shape.
2 - Ion exchange.
3 - Reduction of methaemoglobin to deoxyhaemoglobin.
4 - Management of oxidative stress via peroxidase.
List 2 treatments of G6PD deficiency.
1 - Folic acid supplements.
2 - Splenectomy.
What inheritance pattern is shown by a G6PD deficiency?
X linked recessive.
List 6 factors that serve as evidence of haemolysis.
1 - Anaemia.
2 - Hyperbilirubinaemia.
3 - Reticulocytosis (an increase in reticulocytes).
4 - Raised lactate dehydrogenase.
5 - Reduced haptoglobin (binds to free Hb to facilitate removal).
6 - Direct antiglobulin test negative.
What is sideroblastic anaemia?
- A condition in which the bone marrow produces sideroblasts rather than erythrocytes.
- Sideroblasts are nucleated erythroblasts with granules of iron accumulated in the mitochondria surrounding the nucleus.
- The body therefore has iron available but cannot incorporate it into haemoglobin.
List 5 physiological effects of hypothyroidism that may contribute to anaemia.
1 - Bone marrow depression.
2 - Decreased erythropoietin production.
3 - Iron deficiency.
4 - Vitamin B12 deficiency.
5 - Folate deficiency.
Define microcytic, normocytic and macrocytic anaemia.
- Microcytic anaemia is the presence of small, often hypochromic erythrocytes.
- Normocytic anaemia is the presence of erythrocytes that are normal in size but low in number.
- Macrocytic anaemia is the presence of large, often hyperchromic erythrocytes.
List 4 causes of microcytic anaemia.
1 - Iron deficiency.
2 - Thalassaemia.
3 - Chronic disease.
4 - Sideroblastic anaemia.
List 2 causes of normocytic anaemia.
1 - Anaemia of chronic disease.
2 - Acute bleeding.
List 6 causes of macrocytic anaemia.
1 - B12 deficiency.
2 - Folate deficiency.
3 - Haemolysis.
4 - Drugs (e.g. hydroxycarbamide and antiepileptics).
5 - Myelofibrosis.
6 - Excessive alcohol consumption and liver disease.
Define anaemia of chronic disease.
A type of anaemia that affects people who suffer from chronic conditions that cause inflammation, namely:
- Infections,
- Autoimmune diseases,
- Cancer and
- Chronic kidney disease.
List 5 clinical tests that should be done in an investigation for anaemia.
1 - Full blood count and smear.
2 - Ferritin, B12 and folate levels.
3 - Liver and kidney function.
4 - Haemolysis screen.
5 - Immunoglobulins.
What is the function of ferritin?
To bind and store iron.
List 4 places in which ferritin is found.
1 - Bone marrow.
2 - Liver.
3 - Spleen.
4 - Skeletal muscle.
Define myelofibrosis.
A malignancy of bone marrow that causes scarring / fibrosis of bone marrow.
List 4 causes of sideroblastic anaemia.
1 - Excessive alcohol consumption.
2 - Pyridoxine deficiency.
3 - Lead poisoning.
4 - Copper deficiency.
