anaemia Flashcards
how is anaemia measured clinically?
reduced Hb concentration
what two factors are needed to calculate the Hb concentration?
red cell mass
plasma volume
What are the normal Hb ranges?
men: 131 – 166 g/L
women: 110 – 147 g/L
give an example of reduced Hb but increased red cell mass
drinking a lot of water
what is quality control?
if you put the same sample through multiple times, you could end up with different readings
What are the consequences of anaemia?
reduced o2 transport, so tissue hypoxia
compensatory changes
pathological consequences
What are the compensatory changes in anaemia?
increase tissue perfusion eg tachycardia
increase o2 transfer to tissues
increased red cell production
what are the pathological consequences of anaemia?
Myocardial fatty change Fatty change in liver Aggravate angina/claudication Skin and nail atrophic changes CNS cell death (Cortex and basal ganglia)
where are red blood cells produced?
bone marrow
what is the lifespan of an RBC?
120 days
which organs/tissue remove RBCs from the body?
spleen
liver
bone marrow
blood loss
How do we know where someone is on the red cell balance - ie the balance of RBC production and removal?
reticulocyte count
What are reticulocytes?
immature red blood cells released from the bone marrow
If there is too much removal of RBCs, what will happen to the reticulocyte count?
increase
if there is a problem with bone marrow production of RBCs, but no problem with removal of RBCs, what will happen to the reticulocyte count?
decrease
What is the first thing you look at in the results if sb is anaemic?
mean cell volume (the same as mean corpuscular volume) then split into: microcytic normocytic macrocytic
what is the unit for MCV?
femtolitres
what are the three main causes of microcytic anaemia?
iron deficiency
thalassaemia
anaemia of chronic disease
How is iron deficiency tested?
ferritin
Why is ferritin not a reliable marker for iron deficiency?
it rises in infection, inflammation and malignancy as it is an acute phase protein
so a low ferritin is diagnostic of iron deficiency, but a raised ferritin does not rule it out
What are the causes of iron deficiency?
not enough in the diet haemmorhage incl. menorrhagia malabsorption pregnancy breast feeding - breast milk is iron deficient hookworm cancer
Give some examples of conditions that can cause anaemia of chronic disease
kidney failure, Crohn’s, RA, cancer, heart failure
Why does kidney failure lead to anaemia?
the kidney makes erythropoietin and as the kidneys fail, not enough epo is made
Give examples of causes of normocytic anaemia
- acute blood loss - over time through in chronic blood loss, iron deficiency will result
- anaemia of chronic disease
- combined haematinic deficiency (B12 and iron deficiency)
what is erythropoeisis?
formation of RBCs in the bone marrow
what are the causes of macrocytic anaemia?
B12/folate deficiency
Alcohol excess/liver disease
Hypothyroid
HAEMATOLOGICAL
What are the haematological causes of macrocytic anaemia?
Antimetabolite therapy - eg chemo
Haemolysis - reticulocytes are bigger than RBCs
Bone marrow failure - congenital or acquired
Bone marrow infiltration eg by cancer; leukaemia/lymphoma
How do we investigate anaemia?
Thorough history and examination FBC +film Reticulocyte count U/E’s, LFT’s, TSH B12, folate, ferritin
