TGN test variability

Hi all,

I'm new here but I have had Crohn's for a while. I was wondering if others monitored their 6-TGN levels while on 6MP or azathioprine? I understand the test indicates how effective the drug is but I have noticed my levels jump around while I am on a constant dose of 6MP. When I mean jump around, I mean like moving from 150 to 400 while on a constant daily dose of 25mg (I think the theraputic range is 250-450). Any thoughts as to why the results move would be great.

thanks

26F, Crohns 8 years, pentasa, 6MP.

Thanks for the reply Ivy, I'm a New Zealander.

The 6-TGN test stands for 6-thioguanine nucleotides. Here is a link to a NZ article on the topic

http://www.nzma.org.nz/journal/116-1178/531/

I think it is mainly used when people start on azathioprine or 6MP to adjust doses, but I have had blood tests for this for a few years now and I can't work out why the results vary.