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