Red cell disorders Flashcards
Anaemia
reduced levels of Hb
symptoms of anaemia
shortness of breath
lethargy
tachycardia
weakness
is skin colour a reliable sign for anaemia?
no- conjunctiva and nail beds may be pale
severe anaemia in elderly can cause
angina
signs of anaemia
glossitis (painful red tongue)
angular cheilitis (fissures at corner of mouth)
DPGs may be elevated in RBCs so O2 more readily given up
iron deficiency anaemia
microcytic (decreased mean corpsular volume) input reduced (diet/ removal of stomach) or output increased (menstruation, GI bleeding ulcers, use of NSAIDs, colon cancer
demand increased from pregnancy
when bone marrow and macrophage iron stores depleted
monitor full blood count
give iron sulfate
Acute iron deficiency anaemia
rapid loss of blood- haemorrhage
bp falls
haemodilution
chronic iron deficiency anaemia
long term bleeding- gastric bleeding, excessive menstruation
acute vs chronic anaemia FBC
HB: decreases both haematocrit decrease both MCV: decrease in chronic reticulocyte: increase in chronic WBC: decrease in acute platelets: decrease in acute EPO: increase in both DBG may be elevated to try to transport more oxygen iron stores: normal in acute and zero in chronic
Treatment of iron deficient anaemia
find and treat underlying cause
oral iron sulfate (take with food as irritates stomach)
prophylaxis in pregnancy: oral iron with folic acid before and after conception- precursor to DNA, reduces chance of neurotube defect, produces RBC
transfusion
renal anaemia
complicates CRF- impaired kidney doesnt produce EPO normocytic anaemia (lack of stimulation to produce RBC) treat with iron and EPO
pregnancy
dilution/ iron deficiency
normocytic- pregnancy increase MCV but iron deficiency decreases it
Megaloblastic anaemia
rare form of anaemia
abnormal RBC maturation due to defective DNA synth
bone marrow contains megaloblasts (abnormal precursor cells)- nuclear maturation impaired compared to cytoplasm
if macrocytic and not anaemic- alcohol
why is megaloblastic anaemia macrocytic?
vit B12 or folate deficiency (increased in alcohol abuse)
anaemia, jaundice (XS breakdown of Hb due to ineffective erthryopoiesis)
symptomless, diagnosed on blood test
larger RBC more likley to breakdown
what is B12 essential for?
cofactor for (THF) purine and pyrimidine synth (cell division) requires Castle's intrinsic factor for absorption (absence after gastrectomy)
• Folate (folic acid) - essential for thymidylate synthesis (a rate limiting step in DNA synth as thymidine is a pyrimidine base), use in pregnancy
Most foods (esp. liver, greens, yeast, marmite)
• Methotrexate - inhibits dihydrofolate reductase (therefore folate regeneration impaired - treat with folinic acid), immunosuppressant, impairs DNA synth
• Pernicious anaemia - lack of intrinsic factor for absorption of B12 due to autoimmune disease - treat with hydroxocobalamin i.m. (bypass absorption)
• Crohn’s Disease- malabsorption of B12, folate or iron
haemolytic anaemia
increased rate of RBC destruction
• Spherocytosis - genetic - abnormal reduction in RBC membrane protein (spectrin) - cells fragile
• Acquired - haemolytic transfusion reaction, malaria, drug-induced
• causes Jaundice (?) and enlarged spleen (red cell destruction) - folate deficiency may occur due to increased erythropoiesis
sickle cell anaemia
Genetic SNP: single nucleotide polymorphism
valine substituted for glutamic acid
abnormal Hb- crystals at low o2 can block microcirculation- muscle pain- can cause haemolytic anaemia
Thalassaemia
Genetic- deletion of genes
Reduced rate of alpha or beta globin units production many variations e.g. deletion of both alpha-genes leads to death in uterus as Hb (gamma4) produced
one alpha deletion- reduced haematocrit and RBC volume
Aplastic anaemia
insufficient production of RBC, platelets (pancytopenia) and WBC (can just be RBC pure red cell aplasia)
decreased resistance to infections, increased bleeding and tiredness
how is aplastic anaemia acquired?
viral, radiation and drugs Cytotoxic (anticancer) agents Chloramphenicol- antibiotic Sulphonamides- antimycrobial Insecticides
treatment of aplastic anaemia
- Immunosuppressants – prevent immune destruction of stem cells
- Colony-stimulating factors - increase WBC count
- Bone marrow transplant - with tissue match
polycythaemia
Increased Hb content and haematocrit (>55 in males and >47 in females)
increased blood viscosity- poor tissue perfusion
signs and symptoms of polycythaemia
Ruddy appearance Headaches Blurred vision Hypertension Cyanosis- sluggish blood flow- deoxygenation
causes of polycythaemia
treatment
primary: changes in bone marrow, stem cell defect
secondary: increased EPO- altitude, smoking, renal carcinoma and COPD
treatment of primary: venesection (bleeding), radioactive phosphorous (reduce turnover stem cells), cytotoxic agents- myelosupression (target RBC)
