MedEd Lecture 2 Flashcards
Anaemia values in men and women
Men = < 130g/ml
Women = <120g/ml
Three general mechanisms behind anaemia
- Blood loss
- Decreased RBC production
- Increased RBC destruction
Causes of microcytic anaemia
Iron deficiency, thalassaemia, sideroblastic
Most common cause of iron deficiency anaemia
blood loss
Key features of iron deficiency anaemia on film and blood test
Pencil cells on peripheral blood smear
Decreased iron, ferritin
Increased transferrin and total iron binding capacity
Reactive thrombocytosis - iron normally inhibits thrombopoiesis
Iron study results in iron deficiency anaemia and why
Low iron and ferritin - due to lower storage of iron
Increased transferrin - to try and compensate and increase iron transport
Increased total-iron binding capacity - because you transferrin is better at keeping a hold of iron when you really need it
Key features of thalassaemia on blood smear
- basophilic stippling = aggregation of basophilic granules dispersed through the cytoplasm of erythrocytes
- target cells
Iron study in thalassaemia
normal
What is sideroblastic anaemia?
Basically you have enough iron but you can’t incorporate it into the haemoglobin
You get iron build up forming ringed siderblasts (erythroid precursors)
What happens to the mitrochondira in siderblastic anaemia?
iron gets stuck in them
Causes of siderblastic anaemia
Congenital
Acquired - excessive alcohol, lead poisoning
Key features of siderblastic anaemia
- basophilic stippling
- iron studies: raised iron, ferritin, low transferrin, low total-iron binding capacity
- bone marrow: ringed sideroblasts
Causes of macrocytic anaemia
Megaloblastic: B12 deficiency, folate deficiency
Non-megaloblastic: alcohol, hypothyroidism, pregnancy
How does alcohol cause macrocytic anaemia?
- deposition of cholesterol into erythrocyte membrane increases the size of the cell
How does hypothyroidism cause a macrocytic anaemia?
T3 helps with EPO production which are needed for RBC production
How to differentiate B12 deficiency and folate deficiency anaemia
- Duration - folate = months, B12 = years
- Clininal - B12 = neurological changes
- Methylmalonic acid is raised in B12 deficiency
Schilling test - positive in B12 secondary to pernicious anaemia - Drug Hx - phenytoin inhibits folate absorption
Megaloblastic vs non-megaloblastic
Megaloblastic has hypersegmented neutrophils
Causes of normocytic anaemia
- Haemolytic: inherited or acquired (immune-medicated or non-immune mediated)
- Non-haemolytic: anaemia of chronic disease, failure of erythropoiesis
What is anaemia of chronic disease and what are the iron studies?
Secondary to infection, inflammation, malignancy
- immune system gets activated by auto-antigens, tumour antigens etc and that increases cytokine production, which increases hepcidin
- Hepcidin stops the absorption of iron in the intestine
- So iron storage goes up so increased ferritin and iron, decreased transferrin and TIBC
Causes of inherited haemolytic anaemia
- Membrane affected = Hereditary Spherocytosis
- Cytoplasm affected: G6PD deficiency
- Haemoglobin affected: Sickle cell
Causes of acquired haemolytic anaemia
- Immune: autoimmune warm vs cold, alloimmune: ABO or rhesus
- Non-immune: microangiopathic vs macroangiopathic, infection,
Inheritance of hereditary spherocytosis
autosomal dominant
What is hereditary spherocytosis?
- defect in vertical interaction (proteins) of the red cell membrane
Key features of herediatry spherocytosis in terms of tests
- peripheral blood smear = spherocytes, polychromasia
- positive osmotic fragility test (more fragile)
- positive eosin-5-maleimide (basically a specific substance isn’t taken up as much cos the membrane is shit)
