Anaemia Flashcards
What are the reference ranges for anaemia?
Hb:
Men: <135 g/L
Women: < 115g/L
(Note: there is a growing argument that women should be labelled anaemic based on male
reference ranges, as a lot of women with Hb 115-135 will actually have iron deficiency)
What are the three main mechanisms which result in anaemia?
Reduced RBC production
Loss of RBCs (haemolytic anaemias)
Increased plasma volume (pregnancy)
What are the signs in severe anaemia (Hb < 80g/L)?
Hyperdynamic circulation
e.g. tachycardia, flow murmurs (ejection-systolic over apex)
Can lead to heart failure
What does a high MCV mean in anaemia?
Often decreased production of RBCs
What does a low MCV mean in anaemia?
Often a normal number of RBCs but not enough haemoglobin to go in them
List the causes of a microcytic anaemia:
(FAST)
F: Iron-deficiency
A: anaemia of chronic disease
S: Sideroblastic anaemia
T: Thalassaemia
List the causes of a normocytic anaemia:
Acute bleed
Anaemia of chronic disease
Bone marrow failure
Renal failure
Hypothyroidism
Haemolysis
Pregnancy
List the causes of a macrocytic anaemia:
(FATRBC)
F: Foetus
A: Antifolates (e.g. phenytoin, methotrexate)
T: Hypothyroidism
R: Reticulocytosis
B: B12 or folate deficiency
C: Cirrhosis
+ Myelodysplastic syndromes
What is Reticulocytosis?
Release of larger immature cells e.g. in haemolysis
What are the signs of iron deficiency anaemia?
Koilonychia, atrophic glossitis, angular cheilosis, post-cricoid webs (Plummer-Vinson syndrome), brittle hair and nails.
What would you see on a blood film with Iron deficiency anaemia?
Microcytic, hypochromic, anisocytosis (varying size), poikilocytosis (shape) pencil cells.
What are the 5 main underlying mechanisms of iron deficiency anaemia?
Blood loss
Increased utilisation
Decreased Fe intake
Decreased absorption
Intravascular haemolysis
List common causes of IDA through blood loss:
Meckel’s diverticulum (older children)
Peptic ulcers / Gastritis (chronic NSAID use) Polyps/colorectal Ca (most common cause in adults >50yrs)
Menorrhagia (women <50 yrs)
Hookworm infestation (developing countries)
When might increased utilisation of RBCs cause IDA?
In pregnancy/lactation
Growth in infants/children
When might problems with absorption cause IDA?
Coeliac (absence in villous surface in duodenum)
Post-gastric surgery
(rapid transit / reduced acid which aids Fe absorption)
What causes of intravascular haemolysis cause IDA and how?
Microangiopathic haemolytic anaemia
Paroxysmal nocturnal haemoglobinuria
Loss of Hb in urine results in Fe deficiency
What investigations should be carried out for a pt with IDA with no obvious cause?
OGD + Colonoscopy
Urine Dip
Coeliac screen
What are the indications for IV Iron replacement?
Poor oral absorption
Failure of oral trial
Need for rapid rise
Note: Fe does not absorb well in sepsis and fuels bacteria
What are some common causes of Anaemia of chronic disease?
Chronic inflammation (e.g. TB, osteomyelitis)
Vasculitis
Rheumatoid arthritis
Malignancy
(Renal failure)
Explain the aetiology of anaemia of chronic disease:
Cytokine driven inhibition of RBC production
Inflammatory markers like IFNs, TNF and IL1 reduce EPO receptor production (and thus EPO synthesis) by kidneys
Iron metabolism is dysregulated. IL6 and LPS stimulate the liver to make hepcidin, which decreases iron absorption from gut (by inhibiting transferrin) and also causes iron accumulation in macrophages.
What happens to Ferritin in anaemia of chronic disease?
High (unless coinciding IDA)
(Ferritin is intracellular protein iron store)
Fe is sequestered in macrophages to deprive bacteria