Gadolinium in Feces: From whence does it come?

I am a GI radiologist and a body MRI expert... and yet I have never liked the subject of feces, nor the anal canal. A number of GDD sufferers have used activated charcoal or zeolyte to aid them in their quest to remove Gd. Some have sent samples off for testing to labs such as Doctors Data.. I am not prepared for my clinic to do that. I have considered that bowel removal agents were a fool's errand for most GBCAs - but maybe I have been wrong.

I have seen a report from an individual who received Gadavist, in whom feces Gd content went up following activate charcoal

How could this happen?

We have to take a step back to examine why I would ask that question. Only Multihance and Eovist (Primovist in other countries) experience any amount of hepatobiliary elimination. Eovist about 50% eliminated by the hepatobiliary route, and Multihance 5 %. So that percentage of GBCA for those agents is eliminated by the biliary system and ends up in feces. The remainder of the the GBCAs are eliminated by the kidneys. Omniscan, Optimark, Magnevist, Gadavist and Prohance are termed nonspecific extracellular agents, and they are eliminated almost exclusively by the kidneys.

So if Gadavist is eliminated exclusively by the kidneys, how is it that there is some in the feces to begin with, and then more is eliminated by activated charcoal. Even if eovist was the agent given, how is it that more Gd is removed following activated charcoal?- we would not expect activated charcoal to stimulate more biliary elimination, not like we would expect a large all-you-can-eat buffet would do. If I was to use an oral agent to remove Gd on myself, I probably would use a gentler agent like metamucil, as without a study I am not sure of the advantage of the others.

Conventional medical knowledge informs us that the small bowel is where all the nutrients and other particles are absorbed/incorporated into the body. The colon is involved in water transport back and forth- more fluid eliminated- diarrhea. So where is the Gd in feces, secondary to Gadavist, coming from. A simple answer may be that the Gd is being eliminated from anal glands, much like Gd is eliminated from sweat glands (particularly apocrine glands: arm pits and groin region). The anal canal is also part of a different blood supply than the remainder of the stomach/small bowel/ colon, it is part of the systemic circulation, whereas the others are part of the portal circulation. This could be tested for by sampling stool above the anal canal, and stool that has exited through the anus, examining for Gd content.... I am not going to do that research....

Could it be that there is an active or passive transport system, that medical science is not yet aware of, that transports toxic/ noxious elements from the body out through the GI tract. If so it would seem the small bowel is the likely organ that this occurs in. Activated charcoal, or similar, then simply picks up more Gd that is lining the luminal surface of small intestinal villi and carries it out?

Will one of the other silver linings of the dark cloud of GDD be that it teaches us more about physiology than we knew before?

Gd in feces? From whence?

Richard Semelka, MD