13.05.10 Haematology and HIV


    • 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


    • 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!


    • 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


    • 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