Table 1

6-Thioguanine (6-TG) metabolite levels: correlation with clinical efficacy

6-TG >250 pmol/8×108 RBCs
Disease n Remission Non-remission p Value
Fistulising/Crohn's 8 2/20/6<0.01
Colonic Crohn's2612/151/11<0.01
Ileocolonic Crohn's29 6/162/13NS
All Crohn's6320/333/30<0.01
Ulcerative colitis1911/142/5NS
All8231/455/37<0.01