Anaemia, Vit B12, Folate & Polycythaemia Flashcards
Define anaemia
Decrease in the amount of RBCs/Hb = blood loss, decreases prod, increased removal
What are the symptoms and signs of anaemia?
Symptoms = tiredness, pallor, reduced exercise tolerance, angina, palpitations, devel of heart failure.
Signs = pallor, tachycardia, increases resp rate, epithelial changes
What are the 3 causes of reduced erythropoiesis?
1) Empty bone marrow = unable to response to EPO.
2) Infiltrated marrow = cancer.
3) Lack of response to haemostatic loop = e.g. kidneys stop making EPO in disease
What is dyserythropoiesis and its clinical examples?
Dysfunctional erythropoiesis
anaemia of chronic disease (ACD),
myelodysplastic syndromes (MDS): prod of abnormal marrow stem cells = macrocytic anaemia
How does megaloblastic anaemia arise?
1) Vit B12 def = diet, intrinsic factor def, disease of ilium, transcobalamin def (delivers B12 to one marrow)
2) Folate def = diet, duodenum/jejunum disease, drugs
How does B12/folate def present on a blood film?
Macrocytic RBCs, hypersegmented neutrophils
What is pernious anaemia?
Autoimmune disease = attacking gastric parietal cells = low intrinsic factors = can’t bind B12 to absorb it
Give clinical example of anaemia due to Hb synthesis errors
Thalassaemia, sickle cell disease
Name some disorders in which RBCs membrane structure leads to anaemia
Hereditary spherocytosis, hereditary elliptocytosis, hereditary pyropoikilocytosis, hereditary stomatocytosis
How can damage to RBCs be acquired?
Heart valves, vasculitis, DIC, burns, drowning causes osmotic change
How can loss of RBCs cause anaemia?
Haemorrhage = lower the RBC count = injury, ulceration, excessive menstruation
In what circumstance in the removal of RBC increased?
Haemolytic anaemia, either intravascular/extravascular (RES) – can be autoimmune
What are the basic investigations to request when you suspect haemolytic anaemia
Increased reticulocytes, raised bilirubin, raised LDH
How can anaemia be classified?
Mechanism, size (macro/normo/microcytic), presence/absence of reticulocytosis
What is the significance of a reticulocyte?
Means that the bone marrow is functional
In what circumstances do you see an overproduction of RBCs?
Physiological reaction or myeloproliferative neoplasms (essential thrombocythaemia, polycythaemia vera)
Outline polycythaemia vera
High haematocrit OR raised RBC mass, Jak2 mutation present (= increased prolif + survival of haematopoietic precursors).
Causes = arterial/venous thrombosis, haemorrhage, pruritus, splenic discomfort, gout
What is erythrocytosis?
Increased in [RBC]:
Relative = normal RBC mass, but decreased plasma vol.
Absolute = increased RBC mass
How is polycythaemia vera managed?
Venesection, aspirin, drugs to reduce overprod of cells
What is a sign of intravascular haemolysis?
Haemoglobinaemia
What does a direct Coombs test measure?
Abs bound directly to the surface of RBCs
What are the causes of microcytic anaemia?
Hint: TAILS
T: thalassaemia A: anaemia of chronic disease I: iron def anaemia L: lead poisoning S: sideroblastic anaemia
Which cellular process is most affected by folic acid def?
DNA synthesis
What is the best source of B12?
Foods of animal origin
What is a schistocyte?
RBC fragment
What is a physiological responce to anaemia?
Increase 2,3-bisphosphoglycerate
= promotes release of oxygen bound to Hb, thus enhancing ability of RBCs to release oxygen near tissues
