Microcytic anaemia Flashcards
What is microcytic anaemia?
type of anaemia where the circulating RBCs are smaller than normal
What does MCV stand for?
mean corpuscular volume
what does MCV measure?
avg volume of a RBC
what’s the normal MCV range?
80-100 fL (femto = 10^-15)
Microcytic anaemia is defined by what MCV?
<80 fL
What are the three types of microcytic anaemia we need to know about?
Fe deficiency
alpha and beta thalassemia
sideroblastic
Give three symptoms of anaemia
fatigue
palpitations
pale skin
Why does iron deficiency lead to anaemia?
Iron is needed in haem formation
lack of haem = lack of effective RBCs
Give four causes of iron deficiency?
What percentage of men and women are iron deficient in the UK?
2% of men
14% of non-pregnant women and 38% in pregnant women
Diagnostic criteria of iron deficiency?
Serum ferritin < 30 mg/L
results affected by:
infection
inflammation
pregnancy
Treatment for iron deficiency?
oral iron tablets continued for 3 months after iron deficiency cleared:
ferrous sulfate
ferrous fumarate
ferrous gluconate
How long should iron tablets be continued after the iron deficiency is resolved?
3 months
What three ferrous tablets can be given for iron deficiency?
ferrous sulfate
ferrous fumarate
ferrous gluconate
Diagnostic definition of anaemia in males and females (pregnant and non-pregnant)?
males - Hb < 130 g/L
females - Hb < 120 g/L
females (pregnant) - Hb < 110 gL
Two common signs of iron deficiency?
pallor
atrophic glossitis (loss of papillae on the tongue)
Two common signs of iron deficiency?
pallor
atrophic glossitis (loss of papillae on the tongue)
Describe the structure of a haemoglobin molecule?
Roughly how many molecules of haemoglobin are in each red blood cell?
260 million
Roughly how many red blood cells circulate in the average person?
25 trillion
three side effects of iron tablets?
black stools
constipation
nausea
What is thalassaemia?
an inherited blood disorder characterised by decreased haemoglobin production
What mode of inheritance is thalassaemia?
AR
What happens to the RBCs in thalassaemia?
They’re more fragile and break down easily
What can happen to the spleen in thalassaemia?
spleen collects all the destroyed blood cells and swells (splenomegaly)
In chronic anaemia what can happen to bone marrow?
It can swell in order to try and produce more RBCs to compensate for the chronic anaemia
What three things can be used to diagnose thalassaemia?
FBC - microcytic anaemia
Haemoglobin electrophoresis - diagnose globin abnormalities
DNA testing - find the genetic abnormality
Why is iron overload a risk in thalassaemia?
faulty RBCs can’t uptake iron, so it deposits in organs around the body.
What chromosome number is the alpha-globin producing gene on?
What chromosome number is the beta-globin producing gene on?
How many genes are potentially affected in alpha-thalassaemia?
4 genes.
No. affected:
1 or 2 = alpha-thalassaemia minor (usually asymptomatic)
3 = haemoglobin H disease (moderate anaemia)
4 = alpha-thalassaemia major (incompatible with life)
How many genes are potentially affected in beta-thalassaemia?
2 genes
No. affected:
1 = beta-thalassaemia minor
2 = beta-thalassaemia major
How does a diagnosis of beta-thalassaemia help?
Rules out misdiagnosis of iron deficiency + informs for prenatal counselling
How does a diagnosis of beta-thalassaemia help?
Rules out misdiagnosis of iron deficiency + informs for prenatal counselling
What versions of alpha-thalassaemia are caused by different numbers of genes being affected?
No. of genes affected:
1 or 2 = alpha-thalassaemia minor (usually asymptomatic)
3 = haemoglobin H disease (moderate anaemia)
4 = alpha-thalassaemia major (incompatible with life)
what versions of beta-thalassaemia are caused by different numbers of genes being affected?
No. of genes affected:
1 = beta-thalassaemia minor (asymptomatic)
2 = beta-thalassaemia major (severe anaemia and other problems from 3-6 months)
What age does the body start producing adult haemoglobin (HbA) instead of foetal haemoglobin (HbF)?
3-6 months
When is most thalassaemia major detected?
at or before birth (antenatal or newborn screening)
Give two ways beta-thalassaemia major can be managed?
Regular transfusions (every 4-6 weeks)
Iron chelation to avoid iron overload
Iron chelation therapy is a way to reduce the risk of iron overload. Give the name of a drug used for this.
desferrioxamine
When is thalassaemia screened for in pregnant women in the UK?
Pregnant women should be offered a blood test before 10 weeks gestation which will identify for thalassaemia carriers.
When is thalassaemia screened for in pregnant women in the UK?
Pregnant women should be offered a blood test before 10 weeks gestation which will identify for thalassaemia carriers.
What happens in sideroblastic anaemia?
body has enough iron but can’t incorporate it into haem
In sideroblastic anaemia, deficiency of what molecule inhibits the bodies ability to incorporate iron into haem?
protoporphyrin
in sideroblastic anaemia, iron accumulates within RBCs maturing in the bone marrow. What cells are produced instead of RBCs?
ringed sideroblasts
in sideroblastic anaemia, ringed sideroblasts are produced instead of healthy RBCs by the bone marrow. Where in these cells is iron accumulated?
Within the mitochondria, which go on to form a ring around the nucleus.
