haemoglobin

Question 1

in microcytic and macrocytic anaemias, what does MCH tend to parallel

Answer 1

MCV

Question 2

define microcytic anaemia

Answer 2

anaemia with small red cells

Question 3

define normocytic anaemia

Answer 3

anaemia with normal sized red cells

Question 4

define macrocytic anaemia

Answer 4

anaemia with large red cells

Question 5

define anaemia

Answer 5

reduction in haemoglobin concentration (amount of haemoglobin in a given volume of blood) below what would be expected in comparison with a healthy subject of the same age and gender

Question 6

what is a) always reduced and b) usually reduced in anaemia

Answer 6

a) Hb, b) RBC and Hct/PCV as move in parallel

Question 7

what is anaemia usually due to

Answer 7

reduction of absolute haemoglobin in blood stream

Question 8

what can anaemia occasionally be due to

Answer 8

increase in plasma volume, not decrease in amount of haemoglobin

Question 9

in a healthy person, why can’t anaemia resulting from an increase in plasma volume persist

Answer 9

excess fluid in circulation is excreted in urine

Question 10

4 mechanisms of anaemia

Answer 10

reduced production of red cells/Hb in bone marrow, loss of blood from body, reduces survival of red cells in circulation, pooling of red cells in a very large spleen

Question 11

2 causes of anaemia

Answer 11

condition causing reduced synthesis of haem or condition causing reduced synthesis of globin

Question 12

condition causing reduced synthesis of haem

Answer 12

iron deficiency

Question 13

condition with inherited defect causing reduced synthesis of globin

Answer 13

thalassaemia

Question 14

what can help suggest specific causes of anaemia

Answer 14

classification on basis of cell size (microcytic, normocytic, macrocytic)

Question 15

what is microcytic anaemia usually also

Answer 15

hypochromic

Question 16

what is normocytic anaemia usually also

Answer 16

normochromic

Question 17

what is macrocytic anaemia usually also

Answer 17

normochromic

Question 18

common cause of microcytic anaemia: defect in haem synthesis (2)

Answer 18

iron deficiency, anaemia of chronic disease (present in patients with chronic inflammation or infection; starts normocytic and normochromic, but progresses to microcytic and hypochromic; iron remains trapped in macrophages so not available in circulation)

Question 19

common cause of microcytic anaemia: defect in globin synthesis (thalassamia; 2)

Answer 19

defect in a chain synthesis (a thalassaemia), defect in B chain synthesis (B thalassaemia); can be y in neonates

Question 20

what do macrocytic anaemias usually result from

Answer 20

abnormal haemopoiesis so that red cell precursors continue to synthesize haemoglobin and other cellular proteins, but fail to divide normally, causing larger red cells

Question 21

2 anaemia sub-types of macrocytic anaemia

Answer 21

megaloblastic anaemia, haemolytic anaemia

Question 22

macrocytic anaemia: what is megaloblastic erythropoiesis

Answer 22

refers specifically to a delay in maturation of the nucleus (defect in synthesis of DNA) while the cytoplasm continues to mature and the cell continues to grow

Question 23

macrocytic anaemia: define megaloblast

Answer 23

abnormal bone marrow erythroblast

Question 24

macrocytic anaemia: 2 features of megaloblast

Answer 24

larger than normal, shows nucleo-cytoplasmic dissociation (mature cytoplasm but immature nucleus as not condensed)

Question 25

macrocytic anaemia: when can you suspect megaloblastic anaemia but what must you do to be sure

Answer 25

possible to suspect megaloblastic anaemia from peripheral blood features (anaemia, macrocytosis, oval macrocytes, tear drop poikilocytes; hypersegmentation in neutrophils showing right shift), but to be sure requires bone marrow examination (not normally done as check B12 and folic acid)

Question 26

macrocytic anaemia: size difference of young red cells (reticulocytes) vs mature red cells in haemolytic anaemia, and effect on MCV

Answer 26

reticulocytes are 20% larger than mature, so if increased proportion of reticulocytes (polychromasia) in circulation due to premature release, increased MCV

Question 27

5 common causes of macrocytic anaemia

Answer 27

megaloblastic anaemia due to lack of vitamin B12 or folic acid, use of drugs interfering with DNA synthesis (related to megaloblastic anaemia), liver disease and ethanol toxicity, recent major blood loss with adequate iron stores (reticulocytes increased), haemolytic anaemia (reticulocytes increased)

Question 28

3 mechanisms of normocytic normochromic anaemia

Answer 28

recent blood loss, failure of production of red cells (e.g. failed erythropoietin secretion), pooling of red cells in spleen

Question 29

normocytic anaemia: 3 causes of recent blood loss

Answer 29

peptic ulcer, oesophageal varices, trauma

Question 30

normocytic anaemia: 4 causes of failure of production of red cells

Answer 30

early stages of iron deficiency or anaemia of chronic disease, renal failure, bone marrow failure or suppression, bone marrow infiltration

Question 31

normocytic anaemia: 2 causes of hypersplenism

Answer 31

liver cirrhosis, sickle cells trapped in spleen

Question 32

2 features of anaemia on blood film

Answer 32

when spread is less viscous so greater distance between red cells; hypochromia