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Gd in urine following chelation.

A sufferer had recently mentioned to me that if chelation results in 20 times more Gd in 24 hr urine than precontrast, doesn't that mean chelation just results in 20 days of less Gd in a lifetime compared to not receiving chelation?

On the surface it sort of sounds that way.

There are though some critical factors that make it not that way.

First off, chelation is removing Gd from the interstitial space throughout the body, including (and for many of special importance) the brain, so more detrimentally located Gd is removed, than native elimination. Native elimination likely is a negligible elimination that may largely be the slow drip drip from bone..

I have reported these numbers, and have created earlier blogs on it. Following chelation we expect to see atleast 20 times more Gd in urine than pre with linear agents, and atleast 8-10 times more Gd with macrocyclic agents.

1. In many the amount is actually considerably greater in the 40-200 range. Often as well the lower estimates involve rounding the baseline urine value up to atleast 0.1 mcg/24 hours. After 1 year or so following a GBCA injection, often the native elimination is below 1 mcg or even absent, because Gd is now relatively firmly imbedded in tissues.

2. In those settings, just to make it seem reasonable sounding, I have rounded the baseline native elimination up to atleast 0.1. If the real number is 0.1 mcg / 24 hrs and post chelation is 20 (which is common) then the actual excess amount chelation pulls out is 200 times. If the baseline number is 0 and chelations pull out 20, then do I say the amount post chelation is infinitely greater than pre? That has sounded absurd to me so I have rounded the baseline then to 0.1 mcg.

3. Chelation likely removes most effectively protein-bound Gd, of all the Gd species, and protein bound Gd, in my opinion is likely the most biologically active.

The effect of chelation is not simply a oner day event.

4. Not only is there a decay rate of continued elimination due directly to chelation, but the process of re-equilibration, which occurs with chelation, results in the rebalancing to the reservoirs of Gd in the body.

5. As this rebalancing occurs some of that Gd is also eliminated in the urine, probably a sizable fraction.

Therefore there are 5 things (at least) at work regarding the value of chelation for elimination of Gd. In many people the relative amount of Gd pulled out post chelation compared to pre is in the 60-200 range. Also where the Gd is located that is removed with chelation compared to native is crucial (and not known), but it seems that the Gd removed with chelation is often in biologically active locations, as a number of crucial symptoms improve rapidly, like cognitive impairment. My theory is that much of the Gd removed, especially following linear agents, is bound to protein, which likely has the greatest biologic effect.

Richard Semelka, MD