OUTLINE THE MECHANISMS OF ANAEMIA Flashcards
What are the 3 outline causes of anaemia?
reduced production of erythrocytes, increased destruction of erythrocytes, reduced production or defective haemoglobin
what are the signs of anaemia?
pallor (especially conjunctiva), tachycardia, glossitis, koilonychia (spoon nails), dark urine
when are you most likely to see dark urine?
in haemolytic anaemia as RBCs are broken down and excreted too readily
what are the symptoms of anaemia in mild cases?
weakness, tiredness, inability to exercise, dizziness, palpitations, shortness of breath
what are symptoms of anaemia in severe cases?
confusion, thirst, loss of consciousness, jaundice, splenomegaly, hepatomegaly, angina, cardiac failure, fever
what is the differentiation of multipoint haematopoietic stem cells to common myeloid progenitor cells regulated by?
cytokines and haematopoietic niches in the bone marrow
how do the kidney cells know when to excrete erythropoietin?
in hypoxia we get increased levels of HIF which increases the production of EPO
what are pure red cell aplasias?
an anaemia affecting the precursors to red blood cells only.
what’s the difference between primary and secondary pure red cell aplasia?
primary is idiopathic or an autoimmune disease whereas secondary is as a result of exposure to a pathogenic agent
what is pancytopenia?
Pancytopenia is a condition that occurs when a person has low counts for all three types of blood cells: red blood cells, white blood cells, and platelets. Pancytopenia is usually due to a problem with the bone marrow that produces the blood cells.
describe haematopoietic stem cell exhaustion
as the haematopoietic stem cell divides it produces 1 cell that differentiates into a progenitor cell and another that forms another HSC (self-renewal). if something affect the DNA in a HSC then you can lose this self-renewal functioning the cells will only differentiate to form progenitor cells. this is a cause of bone marrow failure
what can cause bone marrow failure?
congenital changes, infections, malignancies, autoimmune disease, drugs, chemicals
what is haemolytic anaemia?
premature destruction of RBCs due to extrinsic or intrinsic mechanisms. the anaemia develops if the bone marrow is unable to match the destruction of RBCs with the formation of RBCs.
what are extrinsic and intrinsic causes of haemolytic anaemia?
extrinsic- when the erythrocyte is healthy but it is destroyed by an external pathological process
intrinsic- when there’s something wrong with the erythrocyte so it is destroyed
what is autoimmune haemolytic anaemia?
when autoantibodies are found as the immune system produces antibodies that recognise their own erythrocytes as foreign and mediate their destruction.
how can you diagnose haemolytic anaemia from blood films?
you get chunks of RBcs and blue-tinged reticulocytes and nucleated red blood cells and very small red blood cells= these mistakes indicate that the body is struggling with haematopoiesis
what is haemoglobinopathy?
what’s the most common type?
an inherited blood disorder in which an individual has an abnormal form of haemoglobin (variant) or decreased production of haemoglobin (thalassaemia)
common= sickle cell anaemia
describe iron related anaemia
a deficiency in iron directly impacts the amount of oxygen that can be bound to haemoglobin
what can cause an iron deficiency?
not eating enough, lack of absorption e.g. gastric atrophy, alcoholism, duodenitis, ulceration, Crohn’s disease
what would you see on a blood film of someone who had iron-deificent anaemia?
the RBcs would be hypo chromic (pale) and microcytic (small), they would seem to be empty due to lack of staining in centre
where can we get iron from naturally?
dark-green, leafy vegetables, iron-fortified cereals, whole grains, beans, nuts, meat, apricots, prunes, raisins and iron tablets
what makes the absorption of iron difficult?
tea, coffee, calcium, antacids, PPIs, wholegrain cereals
what is sideroblastic anaemia?
an impaired ability of the bone marrow to produce normal red blood cells . In this condition, the iron inside red blood cells is inadequately used to make hemoglobin, despite normal amounts of iron. the iron isn’t properly incorporated into the haem
what is the cause of sideroblastic anaemia?
as a result of mutation/deletion of genes regulating th expression of key enzymes in haem synthesis
what would you see in a blood film of someone with sideroblastic anaemia?
iron sat within mitochondria surrounding the erythocytes rather than being packed away
what are key regulators we need in our diet for haem production? what else are B12 and folate required for?
vitamin B6, B12 and folate
essential for DNA synthesis in erythrocyte proliferation so a reduction can reduce erythropoiesis
when is it common to see a vitamin B12 and folate deficiency?
malabsorption, malnutrition, pregnancy, poverty, small bowel disease, gastrectomy, fish tapeworm, antacids
where can we get B12 and folate from in our diet?
meat, fish, milk, eggs, fortified breakfast cereals, soy products
what is microcytic and macrocytic anaemia?
microcytic is when you have a low mean corpuscular volume and microcytic is a high mean corpuscular volume.
what are common causes of microcytic anaemia?
iron deficiency, lead poisoning, sideroblastic anaemia if RBC is low. thalassemia is likely if RBC is high.
what are the common causes of normocytic anaemia?
haemolytic anaemia and bone marrow disorders.
what are the common causes of macrocytic anaemia?
vitamin B12 deficiency, folic acid deficiency, liver disease, deficiency in intrinsic factor or reticulocytosis (increase in reticulocytes)
what is spherocytosis?
the presence of sphere-shaped RBCs in the blood. it is a type of haemolytic anaemia. caused by an increased permeability for sodium and water
what is aplastic anaemia?
when the body doesn’t produce sufficient blood cells. can cause pancytopenia
what is haemorrhagic anaemia?
a low RBC due to a loss of blood.
