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13.05.10 Haematology and HIV

Macrocytosis
  • Drugs causing low B12
    • Omeprazole
    • Metformin
    • N2O
  • Drugs causing low folate
    • Methotrexate
    • Trimethoprim
    • Phenytoin
  • Drugs causing macrocytosis with NORMAL B12 and folate
    • Zidovudine (can check MCV to monitor compliance)
    • Azathioprine
    • Cytotoxics


Steroids

  • Convert "active" rolling neutrophils to circulating (sampleable) neutorphils
    • => RAISE neutrophil count, even though activity is less
  • Lower eosinophils (to zero in everyone except atopics)
  • LABAs raise risk of death in asthma unless given with inhaled steroids


Subacute combined degeneration of spinal cord

  • Bad
  • Due to B12 deficiency
  • MAKE SURE you give B12 if it's low or normal BEFORE you give folate
    • Otherwise cells will suck up all the remaining B12 at the expense of nerves


PE in pregnancy

  • Breasts are particularly radiation-sensitive in pregnancy => No CTPA
  • VQ is just as good as CTPA if CXR is normal
    • But pee quickly to get the radiation out of the bladder
  • Warfarin => Long bone abnormalities
  • LMW heparin is fine, but need to monitor levels (check anti-Xa levels)
  • Can use unfractionated heparin but need to check APTR every 4 hours!



Needlestick
  • Transmission rates
    • HIV 0.3%
    • Hep C 3%
    • Hep B 30%
  • MEDICAL EMERGENCY - HIV prophylaxis best in first hour
  • Treatments
    • HIV: Whole shebang, quick as possible
    • HepC: Peginterferon alpha and ribavirin are no good at blocking transmission (used for treatment only)
    • HepB: Vaccinate and give immunoglobulin if not immune


Notes
  • HIV protease inhibitors block CypP450 very potently and are sometimes included specifically for this reason
  • Co-trimoxazole (trimethoprim/sulfamethoxazole) as PCP prophylaxis
  • CD4 threshold 200 cells/ml
  • Megaloblastic anaemia is a subset of macrocytic anaemia (morphological diagnosis - hypersegmented neutrophils etc)
  • Other things that raise neutrophil count: Lithium, G-CSF
  • Pencil cells are pathognomonic for iron deficiency anaemia
  • Oral iron raises Hb by 1 unit per week
  • CHADS2 = 0 technically needs nothing but probably start aspirin
  • Prothrombin complex concentrate is best for reversing warfarin quickly, but expensive
  • Clarithromycin => Cytochrome P450 inhibition => Warfarin potentiation
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