lecture 2 - overview of anaemias Flashcards
What factors are considered when determining normal Hb concentration of an individual?
age, sex, physiological state (e.g. preganancy), altitude
What are the patient symptoms of anaemia?
weakness, fatigue, heart palpitations, pallor, feeling cold
What are the signs of anaemia upon clinical examination?
pallor, increased pulse rate, heart failure (severe anaemia)
What is an aetiological classification?
A way to classify a condition based on its causes
What are the 2 main aetiological causes of anaemia?
Increased blood loss or destruction, impaired red cell production
What is haemolysis?
RBC breakdown
What are the 2 types of haemolysis?
Inherited, acquired
What are the 3 groups of inherited haemolysis?
cell membrane, cell enzymes, Hb abnormalities
What are the causes of acquired haemolysis?
antibodies, chemical damage, drugs, parasites, etc.
What are some of the causes of the impairment of RBC production due to erythrocyte maturation disturbance?
deficiencies (iron, folate, vitamin B12, etc.), globin gene abnormalities, bone marrow stem cell disturbance
What morphology are the RBCs observed in iron deficiency?
microcytic
What morphology are the RBCs observed in thalassaemias?
microcytic
What morphology are the RBCs observed in renal disease?
normocytic
What morphology are the RBCs generally observed in cancer?
normocytic
What morphology are the RBCs observed in megaloblastic anaemia?
macrocytic
What morphology are the RBCs observed in liver disease/alcoholism?
macrocytic
What morphology are the RBCs observed in myelodysplasia (bone marrow cancer)?
macrocytic
What morphology are the RBCs observed in anaemia of inflammation?
tend to be microcytic, can be normocytic
What is erythroid hypoplasia?
The bone marrow fails to produce sufficient erythrocytes, often due to reduced EPO
What are the components of Haem?
Iron, protoporphyrin
What does iron combine with to form Haem?
protoporphyrin
What is the structure of haemoglobin?
Haem + 2 alpha globin peptides + 2 beta globin peptides
Why does iron deficiency cause microcytic anaemia?
Body is unable to make normal amounts of Hb, meaning the red cells have reduced Hb and are smaller
Why do thalassaemias cause microcytic anaemia?
reduced production of alpha or beta porteins means Hb production is low and cells contain small amount.
Why does inflammation cause microcytic anaemia?
Iron is unavailable, so Hb production is low, leading to small red cells
What is the appearance of RBCs in someone with iron deficiency?
microcytic, hypochromic (pale)
What type of macrocytic anaemia is caused by folic acid or vitamin b12 deficiency?
Magaloblastic anaemia
Why does folic acid or vitamin B12 deficiency lead to macrocytic anaemia?
They are needed for nucleic acid synthesis, meaning their absence causes delayed and abnormal maturation in the marrow.
What are the main causes of non-megaloblastic macrocytic anaemia?
liver disease, increased immature red cell production
Why does renal failure cause normocytic anaemia?
Lack of EPO production slows RBC production
Why can blood loss result in anaemia?
Reduced blood volume means that the kidneys retain salt and water to restore volume, diluting the blood before the RBC concentration can be restored.
What is the cause of lack of iron availability during inflammation?
Liver releases hepcidin peptide which prevents release of iron from stores in the liver, macrophages and spleen.
Why does iron therpay not resolve anaemia of inflammation?
The body has sufficient iron, but is retaining it in iron stores, and reduced digestive absorption of iron
Where are iron stores held during anaemia of inflammation?
Macrophages
What is the minor cause of anaemia in inflammation, aside from iron sequestration?
Reduced response to EPO
Where is CRP produced?
The liver
What does CRP stand for?
C-reactive protein
What is CRP produced in response to?
acute and chronic inflammation
What are red cell rouleaux?
Stacks or aggregations of RBCs in the blood
Why do red cells tend to seperate in normal blood?
They have a strong negative electrical charge on their surface
Why does inflammation cause red cell rouleaux?
Increased concentation of positively charged proteins in the blood neutralises the repelling negative charges of RBCs, causing them to stack together.
What are the main globulin proteins that cause red cell rouleaux?
immunoglobulins (antibodies), fibrinogen (clotting factor)
What is the treatment for anaemia of renal disease?
Subcutaneous injection of EPO (erythropoietin)
What are the 2 main causes of anaemia due to renal disease?
Mainly due to reduced EPO production in the kidneys, some built up waste products shorten red cell survival
What cell type is present in unusually high concentrations in the blood in haemolytic anaemia?
Reticulocytes (immature RBCs)
What are reticulocytes?
Immature red blood cells
What is the morphology of blood cells in haemolytic anaemia?
Contain many reticulocytes - much larger than mature RBCs and have RNA and remnants of cell organelles that appear in stained slides.
What chemical is present in high concentrations in the blood in haemolytic anaemia?
Bilirubin
What is bilirubin?
A breakdown product of RBC/haem recycling
What protein has very low levels in the blood in haemolytic anaemia, and why?
Haptoglobin - us used to mop up Hb from old red cells, so rapidly gets used up when haemolysis is occurring.
