H1, H2: Anaemia Flashcards
1. Define anaemia and distinguish micro/normo/macro 2. Understand effects of iron, B12 and folate deficiency 3. Predisposing factors to anaemia 4. Describe lab features of haemolytic anaemia 5. Outline pathology of congenital and acquired haemolytic anaemia
Life span of RBC
120 days
Where does RBC death occur
Spleen: in in reticuloendothelial system
What is anaemia
Low Hb (not a diagnosis)
What are the causes of anaemia
- Reduced RBC production due to
- iron deficiency
- B12/folate deficiency
- marrow infiltration e.g. cancer
- chronic disease e.g. rheumatoid, cancer - Increased destruction of RBCs due to
- haemolytic anaemia (disorders of RBC membrane, enzyme or Hb) - Loss of RBCs due to bleeding
How is anaemia classified
- Inherited vs. Acquired
- Mactocytic/ Normocytic/ Mactocytic
- Immune vs. Non-immune
What are the causes of microcytic anaemia
- Iron deficiency anaemia
- Thalassaemia
- Chronic disease
What is iron deficiency anaemia
A cause of Microcytic anaemia = most common nutrient deficiency causing defective Hb synthesis meaning RBCs are small, pale, target and pencil cells containing low amounts of Hb (hypochromic)
What are the causes of iron deficiency anaemia
(Iron deficiency ammonia is not a diagnosis itself)
- Pre-menopausal females = Menorrhagia
- Males/Post-menopausal females = GIT bleeding (ulcers, cancer, IBD)
What is thalassaemia
A cause of microcytic anaemia = Autosomal dominant condition where a + B chains are synthesised at a slow rate
What special investigations are carried out for microcytic anaemia
- FBC
- Blood film
- Serum ferritin
- Serum iron
- Transferrin saturation
What are the treatments for microcytic anaemia
Diet, oral iron intake, avoid blood transfusion
What are the causes of normocytic anaemia
- Acute blood loss
- Chronic diseases
- Cancer
- Renal disease
- Haemolysis
How does chronic disease cause anaemia
It can cause either microcytic or normocytic anaemia due to chronic inflammation and infection
- There is a decreased RBC lifespan
- Poor marrow response to EPO meaning
- Decreased erythropoiesis
- Inflammatory cytokines interfere with EPO production
How does cancer cause anaemia
It causes normocytic anaemia because there is marrow infiltration, metastatic cancer (breast, prostate, lung, thyroid ect.), myeloma, myelofibrosis, leukaemia, lymphoma
Outline the clinical features of normocytic anaemia
- Loss of appetite
- Brittle nails
- Pale lips
- Sore mouth
What special investigations are done for normocytic anaemia
Blood film is not useful
MCV is normal
Serum urin and TIBC = low
Ferritin = High
What are the treatments for normocytic anaemia
- Investigate and manage underlying causes
- Erythropoietin hormone to stimulate RBC release
What are the causes of macrocytic anaemia
- Vitamin B12 deficiency
- Folate deficiency
- Haemolytic anaemia
- Autoimmune haemolytic anaemia
- Alcohol
- Drugs
- Liver disease
- Bone marrow failure
- Myelodysplasia
- Haemolysis (if reticulocytosis)
How does vitamin B12 and folate deficiency cause macrocytic anaemia
These are needed for DNA synthesis thus when lowered, cells fail to divide (delayed maturation of nucleus of erythroblast) and this causes large cells
What can cause vitamin B12 deficiency anaemia
This is a macrocytic anaemia called Pernicious anaemia which is autoimmune (autoantibody to gastric mucosa and IF leading to poor B12 absorption)
Why might vitamin B12 and folate deficiency anaemia occur
Due to
- Malabsorption : Coeliac / Crohn’s
- XS utilisation : Pregnancy, Lactation, Psoriasis
- Anticonvulsants, antifolate drugs
What are the clinical features of deficiency state macrocytic anaemias
- Insidious (fatal if untreated)
- Glossitis
- Mild jaundice
- Neurology in B12 deficiency
B12 and folate deficiencies are clinically indistinguishable
How are deficiency state macrocytic anaemias treated
B12
IM B12 injections every 3 months
Folate
Oral folic acid tablets
What is haemolytic anaemia
A cause of macrocytic anaemia where the RBC lifespan <120 days due to abnormalities of
- Membrane due to autoantibodies/spherocytosis
- Hb due to thalassaemia or sickle cell anaemia
- Enzymes (G6P dehydrogenase deficiency = x-linked)
What is hereditary spherocytosis
An autosomal dominant condition where RBCs are spherical so there is less HB and more LDH and unconjugated serum bilirubin - this is a cause of haemolytic anaemia (which causes macrocytic anaemia)
What is sickle cell anaemia
Where there is a point mutation in the globin gene so when [O2] = low, long rod structures are formed (RBC sickles) and this increases rigidity so can block the microcirculation causing ischaemia and pain - this is a cause of haemolytic anaemia (which causes macrocytic anaemia)
What are the clinical features of haemolytic anaemia
(This is a type of macrocytic anaemia)
- Neonatal jaundice
- Acute haemolysis with oxidant drugs and fava beans
- Pallor
- Splenomegaly
- Gallstones
What are the causes of autoimmune haemolytic anaemia
Drugs, CT disease, cancer, blood transfusion:
There is self-reacting IgG antibody that binds to RBC which is then removed by spleen in extravascular haemolysis (this causes macrocytic anaemia)
What investigations are done for autoimmune haemolytic anaemia
- History/examination
- Check serum B21, folate, ferritin
- Repeat FBC and blood film
- ESR
- Renal/liver function
