Theme 2 - Anaemia Flashcards
what are the signs of anaemia (seen by doctor)
- increased pulse and respiratory rate
- spoon nails (kolionychia)
- pale conjunctiva
- tachycardia
What are the symptoms of anaemia (described by the patient)
NON SPECFIC SYMPTOMS
- lethargy
- palpitations
- dyspnoea
- headaches
what defines anaemia?
a fall in Hb concentration below defined levels (160g/L for women and 180g/L in men) therefore insufficient oxygen delivery to tissues
what are the five broad causes of anaemia?
1) bleeding
2) deficiencies - iron, folic acid, B12
3) haemolysis - red cell fragility
4) BM dysfunction - myelodysplasia
5) poor oxygen utilisation or carriage in blood
what are three questions that should be asked when investigating anaemia?
1) Red cell size (MCV)?
2) is it acute or chronic?
3) what is the underlying aetiology?
what is the most common type of anaemia and what is its main cause?
Iron deficiency caused by bleeding (can also be caused by deficiencies or increased requirements eg in pregnancy)
how is occult bleeding diagnosed?
melenaea - dark stool
what are the four principle iron studies two confirm iron deficiency?
1) serum ferritin
2) serum iron
3) serum transferrin
4) % transferrin saturation
how is serum ferritin implicated in anaemia?
IT IS DECREASED
- is the storage form of iron
- increased in iron overload and decreased in iron deficiency
- can also be affected by genetics or in a blood transfusion
what is serum transferrin and how is implicated in anaemia?
IT IS INCREASED
- carrier molecule for iron
- picks up iron from the gut
- if there is iron deficiency then the body up regulates it
how is serum iron implicated in anaemia?
ISNT REALLY
- only reflects recent iron intake therefore if its normal it doesn’t exclude a deficiency
how is % transferrin saturation implicated in anaemia?
GOOD and SENSITIVE MEASURE - LOW IN DEFICIENCY
- shows how much transferrin actually has iron bound to it
- lower if patient is iron deficient
what are the three characteristics in FBC of iron deficiency?
- low serum ferritin (can be normal)
- increased serum transferrin
- low transferrin saturation
how is anaemia of chronic disease characterised?
patient has problem getting iron from the stores to the RBC
- not an iron deficiency
- low transferrin and high or normal ferritin, low serum iron
- %TF saturation is normal
- low EPO (kidney failure)
what generally happens to EPO levels in anaemia?
It is increased as it is released in response to low oxygen levels (as Hb is lower in anaemia)
how much iron taken in from the diet is absorbed and where?
1% absorbed in the duodenum
how long do B12 body stores last?
3-4 years
how long two body folate stores last?
a few months
where is B12 absorbed and how?
in the terminal ileum by receptors for intrinsic factor
how is microcytic anaemia characterised?
- Low MCV (<80)
- Iron deficiency
- beta thalassemia
how is macrocytic anaemia characterised?
- large MCV (>100)
- B12 or folate deficiency (megaloblastic)
- alcoholic liver disease (non megaloblastic)
What is normocytic anaemia caused by?
- anaemia of chronic disease
- haemorrhage
How is the underlying cause of anaemia identified?
on a blood film
what can be identified on a blood film?
the underlying cause of anaemia
- deficiencies due to cell size
- Haemoglobinopathies eg SCA
- polychromasia - high reticulocytes (red cell fragility)
What does the level of reticulocytes show ?
the rate of production of RBC by the BM
what proportion of blood cells should be reticulocytes and what conditions is this increased in?
should be 1%
- > 10% in SCA
- chronic bleeding and haemolysis
what effect does iron deficiency or bone marrow infiltration have on reticulocytes?
decreased reticulocyte numbers
what is pernicious anaemia?
autoimmune condition due to parietal cell loss
- causes deficiency of intrinsic factor
- cells cant absorb B12 from the terminal ileum
how can you test for pernicious anaemia?
with autoantibodies against intrinsic factor
how do you treat pernicious anaemia?
B12 injections
what are 5 causes of anaemia of chronic disease?
1) inflammatory conditions (RA)
2) infections (TB)
3) cancer
4) renal failure
5) autoimmunity
how is anaemia of chronic disease characterised?
POOR UTILISATION OF IRON
- not iron deficient
- iron gets stuck in macrophages
how is EPO implicated in anaemia of chronic disease?
blunted response to EPO
- not making enough rd cells even though iron is. present
how is transferrin implicated in anaemia of chronic disease?
low transferrin and high hepcidin
what type of anaemia is anaemia of chronic disease?
normocytic
what mutation characterises sickle cell anaemia?
point mutation in beta globin gene (autosomal recessive)
what are the main features of sickle cell anaemia?
- unstable Hb
- increased red cell turnover (20 days)
- high reticulocyte numbers
- low blood oxygen
- occlusions in blood vessels
what are the symptoms of sickle cell anaemia?
ischaemia, pain, necrosis, organ damage
how is anaemia managed?
hydration, analgesics, transfusion
what causes the abnormal shaped cells in sickle cell anaemia?
sickle Hb forms filamentous strands which makes inflexible and spiky cells
what are the advantages of being a sickle cell anaemia carrier?
resistance to malaria
how is thalassemia characterised?
inadequate production of Hb due to imbalance of alpha and beta globin
How is Hb implicated in thalassemia?
not enough normal Hb therefore
how to cells appear in thalassemia?
microcytic and hypo chromic as not enough normal Hb
is thalassemia dominant or recessive?
recessive
what are the symptoms of thalassemia?
enlarged spleen, liver and heart
how is beta thalassemia major diagnosed?
with Hb electrophoresis and blood films
- need lifelong blood transfusions
what symptoms are seen alongside myeloma?
anaemia, hypercalcaemia and renal failure
where are BM samples taken from?
iliac crest
how is acute anaemia managed?
- guide by symptoms not Hb levels
- blood transfusion if needed
how is chronic anaemia managed?
find cause then replenish whats missing
- usually few symptoms as body compensates well
- renal failure patients get recombinant EPO
what are the long term risks of blood transfusions?
iron overload (deposits in organs), allosensitivity and autoantibody production against transfused cells
