Anaemia Flashcards
what is anaemia?
reduced total red cell mass
what is the diagnostic criteria for anaemia in adult males?
Hb <130g/L
or
Hct <0.38
what is the diagnostic criteria for anaemia in adult females?
Hb <120 g/L
or
Hct <0.37
where does RBC production take place?
in the bone marrow
what effect does acute blood loss have on Hb concentration?
no change
Hb is a poor marker of acute blood loss
what effect can giving IV fluids have on Hb concentration?
can cause reduced Hb due to haemodilution
even though the number of red cells hasnt changed
what is the normal response to anaemia?
produce more red cells
what is reticulocytosis?
the increased production of red cells
what are reticulocytes?
red cells that have just left the bone marrow
what size are reticulocytes and what effect does this have on MCV?
larger than red cells
increase MCV
describe the appearance of reticulocytes on blood film
stain darker red due to containing remnants of RNA
creates a polychromic picture
how long does it take for up regulation of reticulocytes in response to anaemia to occur?
usually around a week
what is anaemia with low MCV called?
microcytic anaemia
what is anaemia with high MCV called?
macrocytic anaemia
what causes microcytic anaemias?
defects in Hb synthesis combined with intact nuclear machinery allowing division into small cells
what are the building blocks of Hb?
haem = iron + porphyrin globin = proteins
are the cells in microcytic anaemia hypochromic or hyperchromic
hypochromic
what are the five causes of microcytic anaemias?
thalassaemia anaemia of chronic disease iron deficiency lead poisoning sideroblastic anaemia
what are the two causes of a haem deficiency?
lack of iron
problems with porphyrin synthesis
what is the most common cause of microcytic anaemia?
iron deficiency
what two things can rarely cause anaemia by causing problems with porphyrin synthesis?
lead poisoning
congenital sideroblastic anaemias
what disease can result in a microcytic anaemia by causing a globin deficiency?
thalassaemia
what are the two states in which iron can exist?
Fe2+ = ferrous Fe3+ = ferric
what type of iron is required for oxygen transportation?
ferrous (Fe2+)
how can iron be toxic to the body?
generates free radicals if going from Fe2+ to Fe3+
around how much iron is absorbed per day?
1mg/day
where is most iron in the body found?
in Hb
how can you roughly calculate the mg of iron present in the body at any time?
blood volume divided by two
what transfers iron from the iron stores to the Hb?
transferrin
how is iron taken up into the erythroid cells?
via transferrin receptors
where is the major site of iron storage in the body?
the liver
how is iron stored?
in ferritin molecules
what test can be done to assess functional iron status?
Hb concentration
what can be measured to assess transported iron status?
serum iron
transferrin
transferrin saturation
what can be measured to assess storage iron status?
serum ferritin
reflects intracellular ferritin levels
what happens to saturation of transferrin in iron deficiency?
reduces
what happens to saturation of transferrin in anaemia of chronic disease?
reduced
what happens to saturation of transferrin in genetic haemochromatosis?
increased
what do low ferritin levels suggest?
an iron deficiency
what is the first change seen in iron deficiency?
ferritin falls as iron stores are exhausted
what change can be seen when iron deficient erythropoeisis begins occurring?
fall in MCV - cells become microcytic
what epithelial changes can be seen in patients with chronic iron deficiency?
dry skin
koilonychia
angular chelitis
what are the three possible causes of iron deficiency?
lack of dietary intake
losing iron due to blood loss
malabsorptio n
where is iron absorbed?
proximal small bowel
what are the two conservative measures that should be taken for patients with iron deficiency?
review their diet
improve their gastric acidity
review other medications
why is improving gastric acidity beneficial for iron deficiency?
gastric acid is needed for the absorption of non-haem iron
which type of iron is absorbed more easily?
haem iron
what is the aim of treatment in ID anaemia?
normalise Hb
restore iron stores
when will ferritin rise in ID anaemia?
when Hb returns to normla
what increase in Hb is possible by health marrow if well supplied with iron?
7-10g/L per week
what two methods of administration can be used for iron?
oral
IV
name an oral iron preparation
ferrous fumarate
what dose of oral iron is usually given?
100-200mg daily
what oral iron is used in paeds?
sodium feredetate (sytron)
has a lower iron concentration
what are the possible side effects of oral iron?
GI symptoms such as constipation, N+V, abdo pain and dark stools
how long does iron therapy need to be given for to replenish stores?
2-3 months
what should be monitored to assess the response to iron?
rise in Hb, MCV and reticulocytes
what is normal haemoglobin for children aged 6 months to 6 years?
above 110
what is normal haemoglobin for children 6-14?
above 120
what is normal haemoglobin for adult males?
above 130
what is normal haemoglobin for adult females?
above 120
what is normal haemoglobin for pregnant females?
above 110
what should you look for if you suspect haemolytic anaemia?
evidence of RBC breakdown products
reticulocytosis
what are possible causes of macrocytosis without a significant anaemia?
hypothyroidism
alcohol
liver disease
what is renal anaemia?
an anaemia of chronic disease due to failure of erythropoietin production
