anaemia

Question 1

define anaemia, what values are raised

Answer 1

reduction in haemoglobin concentration compared to healthy person of same age and gender

thus, Hb reduced, but also RBC and HCT usually-

Question 2

temporary cause of anaemia

Answer 2

usually due to lower absolute haemoglobin, but can be due to increase in plasma volume- in healthy person this is temporary as excess fluid excreted

Question 3

mechanisms of anaemia, NOT causes

Answer 3

lower production of RBC/haemoglobin in bone marrow

loss of blood

reduced lifespan of RBC

large spleen may cause pooling of RBC rather than in blood

Question 4

cause of lower haemoglobin production in bone marrow

Answer 4

either reduced synthesis of haem (due to lack of iron) or globin ( due to thalassemia

Question 5

classifying anaemia

Answer 5

based on cell size

microcytic, normocytic or macrocytic

Question 6

causes of microcytic anaemia

Answer 6

lower haem synthesis (due to iron deficiency, or anaemia of chronic disease, where chronic inflammation occurs)

defect in globin synthesis (thalassemia), either alpha (lower alpha chain) or beta (lower beta chain) thalassemia

Question 7

macrocytic anaemia

Answer 7

abnormal erythropoeisis where precursors of RBC produce haemoglobin but they don’t divide, so become large

Question 8

macrocytic vs megaloblastic

Answer 8

macrocytic= increased cell size

one cause is megaloblastic erythropoeisis, where nucleus maturation delayed (DNA synthesis impaired), but cytoplasm keeps growing, so cell becomes large- thus megaloblast is an abnormal erythroblast (red blood cell precursor with nucleus)

Question 9

another MECHANISM of macrocytic anaemia

Answer 9

premature release of cells from bone marrow- reticulocytes are larger than RBC, so if there are more of them, average cell size increases

Question 10

causes of macrocytic anaemia

Answer 10

megoblastic anaemia due to B12/folic acid deficiency

drugs affecting DNA synthesis

liver disease/alcohol toxicity

recent major blood loss (loads of reticulocytes produced to combat blood loss)

haemolytic anaemia (increases reticulocytes)

Question 11

mechanisms of normocytic anaemia

Answer 11

recent blood loss (body hasn’t responded yet)

failure of stem cells to produce red cells

pooling of red cells in spleen

Question 12

causes of normocytic anaemia/ normochromic (ie normal synthesis of haem)

Answer 12

blood loss- peptic ulcer, esophageal varices and trauma due to accident

failure of production- renal failure (less erythropoetin), bone marrow failure or early stages of iron deficiency/anaemia of chronic disease

pooling- hypersplenism eg in cirrhosis where spleen enlarges

Question 13

what is haemolytic anaemia and 2 causes

Answer 13

anaemia due to shorter lifespan of RBC (greater haemolysis= more RBC broken down), either due to intrinsic abnormality (issue with RBC itself) or extrinsic abnormality (something acting on normal RBC)

Question 14

inherited vs acquired haemolytic anaemia and causes of each

Answer 14

inherited anaemia due to abnormalities in cell membrane (eg hereditary spherocytosis), haemoglobin (sickle cell) or enzymes (defect in glycolysis due to pyruvate kinase deficiency, G6P dehydrogenase deficiency)

acquired due to extrinsic factors- can be autoimmune (macrophages damage membrane), drugs can cause oxidant damage, and malaria can damage whole cell as well

Question 15

intravascular vs extravascular haemolytic anaemia

Answer 15

intravascular occurs in circulation- acute damage to RBC

extravascular occurs when RBC removed by spleen

Question 16

when to suspect haemolytic anaemia

Answer 16

abnormal red cells (eg more fragments, spherocytes)

more RBC breakdown (high bilrubin- can lead to gallstones/yellow eyes)

more bone marrow activity (more reticulocytes)

anaemia can’t be explained otherwise and is normochormic and normocytic/macrocytic

Question 17

hereditary spherocytosis and effect

Answer 17

inherited intrinsic defect of membrane- cells lose membrane in spleen so become like a sphere

these RBC are more rigid so are removed by spleen (extravascular haemolysis)- bone marrow responds by reticulocytosis: leads to haemolytic anaemia and bilrubin production= jaundice

Question 18

treatment of hereditary spherocytosis

Answer 18

splenectomy- only done in severe cases

because bone marrow very active, folic acid deficiency can occur, so diet is important, and folic acid supplementation given as well

Question 19

G6P dehydrogenase importance

Answer 19

needed for pentose phosphate shunt- protects RBC from oxidant damage (oxidants either intrinsic from blood or extrinsic due to broad beans, chemicals and drugs)

Question 20

effect of G6P dehydrogenase deficiency and who usually vulnerable

Answer 20

gene for G6PD is on X chromosome, so usually occurs in males

causes intravascular haemolysis due to oxidants- forms irregularly contracted cells, and also denatured haemoglobin called heinz bodies

Question 21

treatment of someone with G6PD deficiency

Answer 21

blood transfusion may be needed- then diet restriciton, awareness of harmful drugs/chemicals important

Question 22

autoimmune haemolytic anaemia

Answer 22

autoantibodies bind to red cell antigens, which is recognised by splenic macrophages (complement often present as well), which remove bits of cell membrane= spherocytosis

combination of rigidity of spherocytes and recognition by macrophages leads to removal by spleen

Question 23

diagnosing autoimmune haemolytic anaemia

Answer 23

spherocytes and increased reticulocytes

detection of autoanitbodies to red cell antigens

Question 24

treatment of autoimmune haemolytic anaemia

Answer 24

immunosuppressive drugs like corticosteroids

splenectomy for severe cases

Question 25

microangiopathic haemolytic anaemia causes and treatment

Answer 25

hypertension- treat this

antibody in plasma that causes fibrin deposition in small blood vessels- treat by plasma exchange