microcytic anaemias

Question 1

In what situations are Hb and haematrocrit not good markers of anaemia

Answer 1

rapid blood loss

IV fluids

Question 2

what is the blood film appearance of reticulocytes

Answer 2

slightly larger

slightly more purple (still some RNA)

Question 3

describe the pathophysiological classification OF ANAEMIA

Answer 3

Decreased production (low reticulocyte count)‏
Hypoproliferative – reduced amount of erythropoiesis
Maturation abnormality – erythropoiesis present but ineffective:
Cytoplasmic defects: impaired haemoglobinisation
Nuclear defects: impaired cell division

Increased loss or destruction of red cells (high reticulocyte count)‏
Bleeding
Haemolysis

Question 4

hOW DOES mcv AFFECT THE WAY YOU CONSIDER THE UNDERLYING PATHOLOGY

Answer 4

If MCV low (microcytic) consider problems with haemoglobinisation
If MCV high (macrocytic) consider problems with maturation

Question 5

What do you need to make Hb

How would a shortage of Hb affect colour and MCV

Answer 5

Hb is synthesised in the cytoplasm
To make Hb need
Globins
Haem
Porphyrin ring
Iron (Fe 2+)‏
Shortage in these results in small red cells with a low hb content
The cells are microcytic (small)‏
And hypochromic (lacking in colour)‏

Question 6

list causes of hypochromatic microcytic anaemias

Answer 6

Haem deficiency
Lack of iron for erythropoiesis
Iron deficiency (low body iron)‏
some cases of anaemia of Chronic Disease (normal body iron but lack of available iron) - most normocytic‏
Problems with porphyrin synthesis [ALL VERY VERY VERY RARE]
Lead poisoning
Pyridoxine responsive anaemias
[Congenital Sideroblastic Anaemia (v.rare)]
Globin deficiency
Thalassaemia (trait, intermedia, major)

Question 7

where is iron stored

Answer 7

liver 500mg
Erythroid Marrow 150mg
Macrophages 500mg

Haemoglobin 2500mg

Plasma pool 4mg

Question 8

How is iron transferred and stored

Answer 8

transferrin

ferritin

Question 9

what does transferrin do?

how would %saturation of transferrin vary in with different diseases?

Answer 9

Transports iron from donor tissues (macrophages, intestinal cells and hepatocytes) to tissues expressing transferrin receptors (especially erythroid marrow)
% saturation of transferrin with iron measures iron supply
reduced in iron deficiency
reduced in anaemia of chronic disease
increased in genetic haemachromatosis

Question 10

why is ferritin measured

what level would indicate iron deficiency

Answer 10

Serum ferritin is an easily measured indirect measure of storage iron
Low ferritin means iron deficiency

Question 11

Iron deficiency can be confirmed by a combination of …..

Answer 11

….a microcytic, hypochromic anaemia (decreased functional iron) and reduced storage iron (low serum ferritin)

Question 12

Causes of iron deficiency

Answer 12

Not eating sufficient to meet physiological requirements
RELATIVE deficiency
especially women of child bearing age and children
ABSOLUTE deficiency
vegetarian diets
In general unlikely in men
Losing too much – blood loss (usually gastrointestinal if occult)
Not absorbing enough – malabsorption (relatively uncommon) see lecture on iron metabolism.
Coeliac disease
achlorhydria‏

Question 13

causes of chronic blood loss

Answer 13

Menorrhagia
Gastrointestinal
Tumours
Ulcers
Non-steroidal anti-inflammatory agents
Haematuria