red cells Flashcards
what is the process of RBC differentiation ?
- haemocytoblast
- proerythroblast
- erythroblast
- normoblast
- reticulocyte
- erythrocyte
what substances are required for RBC production ?
metals - iron, copper, cobalt, manganese
vitamins - B12, folic acid, thiamine, B6, C, E
amino acids
hormones - erythropoietin, GM-CSF, androgens, thyroxine
how are RBCs broken down ?
occurs in reticuloendothelial system - macrophages in spleen, liver, nodes
normal RBC life 120 days
globin amino acids are reutilised
haem - iron recycled, haem group becomes bilirubin
bilirubin bound to albumin in plasma
what is hereditary spherocytosis ?
autosomal dominant condition
red cells are spherical, get removed from circulation
what structural proteins are defective in hereditary spherocytosis ?
ankyrin alpha spectrin beta spectrin band 3 protein 4.2
what is the clinical presentation of hereditary spherocytosis ?
anaemia
splenomegaly
pigment gallstones
jaundice - neonatal
what is the treatment of hereditary spherocytosis ?
folic acid
transfusion
splenectomy
what are some other rare membrane disorders ?
hereditary elliptocytosis
hereditary pyropoikilocytosis
south east asian ovalocytosis
what are the 2 key red cell enzyme systems ?
glycolysis - provides energy
pentose phosphate shunt - protects from oxidative damage
what is G6PD ?
commonest enzymopathy
X-linked
glucose 6 phosphate dehydrogenase deficiency - protects haemoglobin from oxidative damage
most common in malaria areas
what is seen on blood films of G6PD deficiency ?
blister cells
bite cells
how does G6PD present ?
variable anaemia
splenomegaly
pigment gallstones
jaundice - neotnatal
drug, broad bean or infection precipitate jaundice or anaemia - haemolysis, haemoglobinuria
what drugs can trigger haemolysis in G6PD deficiency ?
antimalarials - quinine sulphonamides antibiotics - nitrofuratoin analgesics - aspirin antihelminthics - B-naphthol miscellaneous - vit K, methyl blue
what are other rare enzyme deficiencies ?
pyruvate kinase deficiency, reduced ATP, rigid cells
what factors cause Hb to have a lower affinity to O2 ?
acidosis
hyperthermia
hypercapnia
HbF has higher affinity for O2 then HbA
what is the makeup for adult haemoglobin ?
2 alpha chains - 4 alpha genes Chr16
2 beta chains - 2 beta genes Chr11
2% - HbA2 delta chains
HbF - gamma chains
what are the haemoglobinopathies ?
thalassaemia - reduced or absent chain production
sickle cell - structurally abnormal Hb
all autosomal recessive
what is the makeup of HbS ?
2 alpha chains
2 beta sickle chains - point mutation
what is the pathophysiology of sickle cell disease ?
cells polymerise in response to insult, cation loss, dehydration - haemolysis occurs
endothelial activation, promotion of inflammation, coagulation activation, dysregulation of vasomotor tone
vaso-occlusion
what are clinical presentations of sickle cell disease ?
painful vaso-occlusive crisis - bone, chest, stroke
increased infection risk - hyposplenism
chronic haemolytic anaemia - gallstones, aplastic crisis
sequestration crisis - liver, spleen
how do you treat a sickle cell painful crisis ?
analgesia in 30 mins - opiates
avoid pethidine
hydration
O2
antibiotics ?
how do you manage sickle cell disease ?
life long - vaccine, penicillin prophylaxis, folic acid
acute - hydrate, O2, analgesia, prompt infection treatment, blood transfusion
hydroxycarbamide
bone marrow transplant
gene therapy
what is thalassaemia ?
reduced or absent chain production
mutations or deletion
either alpha or beta genes
chronic haemolysis and anaemia
what are the different types of thalassaemia ?
homozygous alpha zero thalassaemia - no alpha chains, hydrops fetalis - incompatible with life
beta thalassaemia major - no beta chains, transfusion dependent anaemia
non-transfusion dependent thalassaemia - range of genotypes
thalassaemia minor - trait/carrier state, hypochromic, microcytic red cells
