Anaemia Flashcards
What is the definition of anaemia?
Reduced total red cell mass (not easy to measure so Hb concentration is used as a surrogate marker)
Reduction in Hb concentration below that which is optimum for that patient or below 95% of the average range for the population
What are the two most common causes of anaemia worldwide?
Iron deficiency anaemia
Anaemia of chronic disease
Below what Hb concentration is anaemia likely to present in adult males and adult females?
Adult males <130g/l
Adult females <120 g/l
Below what Hb concentration is anaemia likely to present in pregnancy?
<110 g/l
What are reticulocytes?
Red cells that have just left the bone marrow - they are immature and larger than normal red blood cells. They still have remnants of RNA.
What colour do reticulocytes stain?
Reticulocytes stain purple/ deep red because they still have remnants of RNA
When is reticulocyte count increased?
In anaemic patients whose bone marrow is functioning normally
There is increased loss or destruction of cells
E.g haemolysis and blood loss
When is reticulocyte count decreased?
In patients with anaemia involving hypoproliferation or abnormal maturation
Different investigations can be done to investigate for; functional, storage and transport iron. What investigations are these?
Functional iron
- Hb concentration
Storage iron
- Serum ferritin
Transport iron
- Serum transferrin
What investigations can be done for anaemia?
Investigations for iron
(Hb concentration, serum ferritin, serum transferrin)
Reticulocyte count
(to assess marrow response)
Haematinics - folate and vitamin B12
MCV
Faecal occult blood testing
GI investigations
What is the problem in microcytic anaemia?
Defects in haemoglobin synthesis = cytoplasmic defect
haemoglobin synthesis occurs in the cytoplasm
What is the problem in macrocytic anaemia?
Defects in DNA synthesis
Cell division is reduced and apoptosis occurs. This means that the cells will be larger (because they do not divide because of the abnormal nucleus) but there will be less of them (since they undergo apoptosis) which is what causes the anaemia.
What two things are needed to make haemoglobin?
Porphyrin ring and iron(Fe2+)
*Shortages in these result in microcytic anaemia
What are the causes of hypochromic microcytic anaemia?
Haem deficiencies
- Iron deficiency
- Chronic disease
- Lead poisoning
- Pyridoxine responsive anaemias
- Congenital sideroblastic anaemia
Globin deficiency
- Thalassaemia
Problems with porphyrin synthesis can rarely cause microcytic anaemia. What are possible causes of this?
Lead poisoning
Pyridoxine responsive anaemias
What is circulating iron bound to and what is it stored as?
Circulating iron is bound to transferrin
Iron is stored in ferritin mainly in the liver
What are some of the possible causes of iron deficiency?
Low consumption
Malabsorption
Blood loss
Why might achlorhydria result in anaemia?
Acid is needed for the absorption of iron
Where is iron absorbed from in the GI tract?
Iron is absorbed from the jejunum (proximal bowel)
How is iron deficiency anaemia managed?
Ferrous iron (Fe2+) supplements
Vitamin C
(helps with the absorption of iron)
Management of the cause
What increase in reticulocytes would you expect per week when a patient is being treated for iron deficiency anaemia?
10g/L/week
Low reticulocytes might suggest poor compliance with iron supplements
How should a patient be managed if they are not compliant with iron supplements?
Try a lower dose and consider adding a laxative for GI symptoms
Can consider IV iron if necessary
What are some of the possible causes of normochromic normocytic anaemia?
Chronic diseases
Renal failure
Hypometabolic states e.g hypothyroidism
Marrow failure
What is the problem in microcytic anaemia?
There are defects in DNA synthesis
Cell division is reduced and apoptosis occurs, this means that the cells will be larger (because they don’t divide) but there will be less of them (since they undergo apoptosis).
What would be the expected lab findings in macrocytic anaemia?
Low RBCs and Hb
High MCV
What units are used for macrocytosis and what is the cut off?
MCV stands for mean corpuscular (cellular) volume
> 100 fl (femtolitres) is macrocytic
What is a megaloblast?
An abnormally large nucleated red cell precursor with an immature nucleus
What is an erythroblast?
A normal red cell precursor with a nucleus
What are the causes of megaloblastic macrocytic anaemia?
B12 or folate deficiency
Drugs
Inherited abnormalities
Where is B12 absorbed fro in the GI tract?
B12 is absorbed from the distal small bowel (ileum)
What are some of the potential causes of B12 deficiency?
Vegan diet
Atrophic gastritis/ PPIs
Chronic pancreatitis
Crohn’s disease
Coeliac disease
What is pernicious anaemia?
Autoimmune condition which results in a deficiency of vitamin B12
Antibodies against IF which is responsible for the transportation of B12
How is pernicious anaemia managed?
Lifelong B12 injections
What other conditions is pernicious anaemia associated with?
Hypothyroidism
Vitiligo
Addison’s
Where is folate absorbed in the GI tract?
Absorbed in the jejunum
What are some of the possible causes of folate deficiency?
Inadequate intake (e.g alcoholics have a poor diet)
Malabsorption
Excessive utilisation (e.g haemolysis, dermatitis, pregnancy and malignancy)
Drugs - anticonvulsants
What are some of the clinical features of B12/ folate deficiency?
Symptoms and signs of anaemia
Jaundice
Neurological problems
Neurological problems are more associated with B12 or folate deficiency?
B12
Posterior/ dorsal column abnormalities, neuropathy, dementia and psychiatric manifestations
How is folate deficiency managed?
Folic acid 5mg daily
What auto-antibodies are associated with pernicious anaemia?
Anti-IF (specific but not sensitive)
Anti-GPC (sensitive but not specific)
What are some of the causes of non-megaloblastic macrocytosis?
Alcohol
Liver disease
Hypothyroidism
Marrow failure
What is meant by spurious macrocytosis?
The volume of the red cell is normal but the MCV is measured as high
What are the possible causes of spurious macrocytosis?
Reticulocytosis
Cold-agglutinins
Why does reticulocytosis cause a spurious macrocytosis?
Reticulocytes are bigger than mature red cells and are analysed along with these for the MCV measurement - they thus cause a false macrocytosis
How do cold-agglutinins cause a spurious macrocytosis?
Clumps of agglutinated red cells are registered as 1 giant cell
Does aplastic anaemia present with; micro, normo or macrocytic anaemia?
Aplastic anaemia presents with normocytic anaemia
Does liver disease present with micro, normo or macrocytic anaemia?
Macrocytic anaemia
What kind of anaemia do hypothyroidism and myelodysplasia present with?
Normoblastic macrocytic anaemia
Red cells that have lost their central pallor are referred to as spherocytes. An excess of these in a patient with a FH of haemolytic anaemia makes what diagnosis likely?
Hereditary spherocytosis
How is autoimmune haemolytic anaemia managed?
Steroids (to suppress the autoimmune process)
Folic acid (to prevent deficiency which can occur when red cell turnover is high)
