For me, the regular 5 mg/kg, every 8 week schedule stopped working pretty fast- I'd get to week 4 & be absolutely miserable, lots of blood, lots of D, up 4-6x per night, etc. Then we increased the dose to 10mgs/kg, every 6 weeks- that has been holding me steady, somewhat. I still get symptomatic by week 5, but it's manageable- on the 6 week dosing schedule I get 4-5 really good weeks, & a week or so of trouble. I have had the prometheus testing done, but that was just to see how I was metabolizing the Imuran- I think though, they do a REmicade antibody test also. My GI never recommended I get the labs done- the increase in symptoms directly correlate to my dosing schedule, so why bother with the labs? Plus, every other GI/surgeon I've spoken with has agreed, that it's slowly losing efficacy. Not one has suggested testing for the antibodies. I'm pretty sure that's how Remicade is supposed to work- after a while, the majority of people build up immunities to it. Are you experiencing this? Sorry to hear it- it's a bummer, eh?