Thanks for the thoughts/insight everyone. Certainly the values above the recommended one were a bit of a mystery to me.
Essentially this blood test has two purposes.
First, it helps verify that you/I are taking the correct initial dosage of infliximab, by measuring the amount of medication within your body when it is at its very lowest point, which is just before your next infusion. There's general guidelines of how much medication you/i should take, but there's a variety of factors (from disease severity differences, to some of us have a faster blood-clearance of proteins than others do) so some of us need more meds than others (10mgs per kilogram instead of 5, and/or infusions spaced closer together). I'd say it would be unusual to take this test before you get on the 8-week maintenance dosage schedule.
Second, it helps explain why a patient begins loosing response later on and checks for your immune system creating anti-bodies to stop remicade, make it less effective over time and even stop working entirely. Say you've been on remicade for multiple years and you are starting to flare. All biologics, including remicade, are essentially antibodies by design. Biologics are tiny proteins that are design to shut off another protein that naturally occurs within our bodies, in this case one called tnf-alpha. Remi is a tnf-alpha-blocker by design. Our immune system looks at those tiny proteins of remicade which look a lot like viruses, and begins attempting to create antibodies to stop said believed virus. The success rate is low, but some of us do eventually succeed. Sometimes more medication will counter it, sometimes you switch to another med (like from remicade to humira) because the antibody concentration is super high. Having antibodies to one tnf-alpha-blocker has no guarantee of you getting antibodies to another, like humira, as the chemical structure between those meds is very different.
The test isn't 100% necessary in all cases (often dosage of remi can be increased experimentally to see if that helps, rather than test beforehand). It does help explain why, in a lot of cases, rather than just guess. Prometheus labs in CA developed the test and calls it Anser IFX, Labcorp offers it, as does Mayo Clinic and others. https://www.labcorp.com/test-menu/29496/infliximab-concentration-and-anti-infliximab-antibody
Moderator Ulcerative Colitis
John, 40, UC Proctosigmoiditis
Rx: Remicade @5mgs/kg/6wks; daily 75mgs 6MP, 4.8g generic-Lialda, and rowasaWow you look great, did you loose weight? Yeah, I lost 20 pounds in a month through this great new program called IBD, you should try it! I wasn't hungry, all I had to do was be doubled-over in pain with frequent diarrhea!