Chelating agents are eliminated from the body relatively quickly, usually within a few hours or days. However, toxic elements can accumulate in the body over a long period of time and be stored in various compartments, some of which may not be easily accessible to chelating agents. Chelating agents typically remove the most readily available metals first, which are often found in the plasma, kidney, liver, and, to a lesser extent, in bone and the central nervous system. When it comes to toxic metals in the nervous system, it's important to use a conservative approach with repeated, modest treatments and the use of multiple agents. With repeated doses, the most accessible pools of toxic elements are depleted, but re-equilibration slowly replenishes these elements in more accessible compartments. This can be observed in the rebound of levels in the blood after discontinuing a chelator, which highlights two important facts.
Firstly, urine, blood, and hair are poor indicators of the lifetime accumulation of toxins in the body (body burden). These measures only reflect recent or short-term exposures, and to a lesser extent, kidney burden.
Secondly, toxic elements stored in bone and soft tissues are not completely immobilized and can migrate back to the bloodstream, causing toxic effects in other tissues. Therefore, it's crucial to gain a better understanding of the amounts of biologically accessible toxic elements in the body that may not be reflected in baseline blood or urine levels before using a chelation provocation.
Lastly, introducing a chelating agent into the body causes shifts of both essential and toxic cations. Aggressive initiation of chelation therapies may result in increased symptoms and is therefore not recommended. Instead, improvements are reported with low initial doses and gradual titration according to patient tolerance, characterized as a marathon rather than a sprint.