Posted 11/24/2021 8:25 PM (GMT -7)
By 'trough levels,' it means testing for levels if infliximab (remicade) right before it's time for the next infusion, like the day before or even the morning before the infusion. Right after an infusion, the levels would be at their highest. Then they gradually decrease until the next infusion. The lowest point is the 'trough.' Ideally, the patient should still have sufficient levels of infliximab at the trough. If they don't, then they're burning through it or metabolizing it all before their next infusion. So infusion frequency and/or dose amount is increased.
The test for fecal occult blood would be a way to see if there is bleeding going on that isn't showing up as actual visible blood in the stool. Bleeding that she's unaware of could explain the iron deficiency. It's a quick easy and fairly cheap test. But it's not really needed if she's going to have a colonoscopy very soon.
As for fecal calprotectin, it's a measure of inflammation in the gi tract, mostly the colon but to a lesser extent the small bowel. As white blood cells fight and die off, a byproduct is calprotectin, which is washed out of the gi tract in the stool. So a measure of calprotectin is an indirect measure of white blood cell activity, which is an indirect measure of inflammation.
It's a fairly good indicator but not perfect. For some people, it only elevates a little even with severe inflammation. For other people, it skyrockets with only mild inflammation. But overall, if you take the measure for hundreds of patients, the higher the number the more inflammation is found. The best way to know how it tracks for her specifically is to measure it several times over time and see how it correlates, for her, to scope results.