Hi - Haven't posted for a long time. I had a rough late Summer and Fall. Found out the hard way that I can't metabolize Imuran. Apparently there is a blood test that should be done before a person starts the medication that can determine if you have a genetic mutation to the enzyme thiopurine
S-methyltransferase (TPMT) that metabolizes thiopurines. If you have poor metabolism, the Imuran builds up and becomes toxic and can be very serious. There is a simple blood test that determines if you have the defective gene. They should do the blood test before starting the medication...in my case they didn't. I'm off the Imuran and started CellCept on Thanksgiving, am back on Prednisone and getting IVIg every two weeks.

Here is a link that might explain the TPMT enzyme better.
http://www.specialtylabs.com/educati...DF/TN_1196.pdf
Gabe