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We also evaluated the binding ability of the oral chelator DMSA with gadolinium. Of the 34 pairs, 24 of the unchallenged urine samples showed slightly higher Gd concentrations than the samples after chelation.
Note: Urine creatinine levels are used to mathematically convert mcg/l values to mcg/g creatinine. This conversion is commonly used today because it reduces the potentially great margin of error that result from an incorrect sample volume given. A low urine creatinine level of 0.3 g/l or less affects the mathematical conversion factor, elevating test results. Low urine creatinine levels are generally the result of overhydration. High urine creatinine levels above 2 g/l are either due to dehydration or renal stress.
Our data clearly indicates that a Gd provocation urine test value can only be judged after it has been compared with a Gd-test result from an unprovoked urine.
Table 7: Gd in Urine Before and After Chelation with DMSA
As expected, DMPS is not able to bind and detoxify gadolinium compounds, and our data indicates that combination treatments involving the chelating agents DMPS, DTPA, EDTA or DMSA seem equally unsuccessful in increasing the elimination of gadolinium via the renal system. The use of oral DMSA may support the thought that Gd-binding could possibly happen, leading to increased renal elimination, but this is highly unlikely as DMSA is a chelator that is chemically similar to, but much weaker than DMPS.
Our data indicates that none of the chelating agents discussed here sufficiently binds and eliminates gadolinium via the renal system. However, just recently, a preliminary case report on 25 patients demonstrated that CaDTPA and ZnDTPA may be useful for the treatment of patients with gadolinium deposition disease (Semelka RC 2018). For that study, 24-hour urine samples were analyzed before and after chelation treatment, showing treatment success. However, not all pre-urine samples were taken immediately prior to treatment. Urine creatinine levels were not specified, which could lead to misinterpretation of results.
Our results are based on urine creatinine levels, but chelation treatment protocols did not involve a 24-hour urine collection. Instead, urine collection was based on the chelator's half-life plus time of administration. For a ZnDTPA injection or an EDTA infusion, that would be 45 minutes plus time of administration.
Clearly, more studies are needed. In future studies, test results should be supported by precise clinical information regarding the contrast agent name, the amount and time of the GBCA given, plus the amount and time of chelating agent administration. Protocols must be determined and followed, including urine collection times.
It would be of interest to find out if linear and macrocyclic GBCAs are retained, and if chelation treatment is an option for linear and macrocyclic GBCAs. Furthermore, it should be cleared if patient reactions are due to gadolinium toxicity or immune reactions, or both, and to which degree renal support such as orthomolecular treatments increase the body's own detoxification ability.
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