Fecal occult blood test vs. Calprotectin stool level (MD use)

Poopydoop, knowing biochemistry, gave us major insight on the (limited) usefulness of Calprotectin level testing. I've seen some MD movement toward Calprotectin test use that appears to replace periodic fecal occult blood testing, and wonder if that's because docs can spend less time with individual patients by not doing the fecal test themselves and requiring patients to deliver stool samples to labs for Calprotectin measurement. Poopydoop has commented that Calprotectin level is most reliable for monitoring lower left/rectal inflammation, but what about UC higher up? Wouldn't the Fecal Occult Blood test be a more reliable indicator of problems above the lower left colon? I'm also wondering if the cost factor plays in here as well. (MD office visit collection/analysis vs. lab delivery specimen test.) RE female patients: ob/gyns have been empowered to perform rectal exams in recent yrs, but they don't test for occult blood. / Old Hat (40+ yrs with left-sided UC; in remission taking Colazal)

Always good to receive your input, Straydog. The Fecal Occult Blood (small dab) specimen gets transferred to a rather minute chemically-treated paper which gives an immediate result, at least that's what my gastro has used longtime-- (no lab needed) until the concern with assessing Calprotectin level in stool (via lab) increased. I got the impression that researchers were looking for an IBD marker that would be more precise than the CRP blood test which can result high for inflammation in other body parts than the gut-- so they adopted Calprotectin measurement about 12 years ago. Back then my gastro's NP called it "a standard of care" issue. It became regarded as "cutting edge" in gastroenterology. But it apparently correlates best in patients with lower left/rectal inflammation, and I think Poopydoop even mentioned that a 1st stool specimen of the day apparently correlates most consistently in measurement. Her remarks plus other members' comments that Calprotectin level doesn't correlate with their inflammatory involvement makes me skeptical about its value as a major marker for IBD. / Old Hat (40+ years with left-sided UC; in remission taking Colazal) P.S. Will look it up on Mayo, thanks again!

Post Edited (Old Hat) : 6/4/2023 10:28:18 AM (GMT-8)

Hi so I'm actually not a biochemist but a scientist in a different field....

I have heard from multiple IBD specialists that calprotectin is most sensitive to inflammation in the rectum. So you could have (for example) a score of 2000 from a few cm of rectal inflammation but a score of 70 with extensive ileitis - the reason being that the calprotectin breaks down as it travels through your colon so the further it has to travel to be pooped out the less will survive.

Regarding the first poop of the day thing .....So I ended up reading several papers on the stability and variability of calprotectin values in patients when I was doing my own measurements. Basically in the course of a day your calprotectin can vary massively (if you are flaring), but in general it is highest in the first poop of the day because it has had time to accumulate overnight (assuming you weren't pooping all night). Therefore if you want to know how "bad" things are then go for the first poop. Also, purely from a scientific point of view it is more consistent if you take the measurement in the same way every time.

As a sample size of one, I can tell you that when i just got "a sample" at any time my numbers were a bit all over the place..but when i consistently went for the first poop of the day it became much easier to see trends..I was also lucky that my doctor let me take measurements every couple of weeks during my last flare when I was close to surgery because doing the frequent measurements also made it easier to see the long term trend.