DMSA administration to patients with alleged mercury poisoning from dental amalgams: a placebo-controlled study

The present investigation was performed to determine the effect of 14-day oral administration of meso-2.3-dimercaptosuccinic acid (DMSA) on the urinary mercury excretion and the potential reduction of blood and plasma mercury concentrations, and also to relate these effects to possible decrease of symptoms, allegedly associated with amalgam fillings. Twenty subjects, relating their symptoms to mercury from amalgam fillings, received 20 mg/kg DMSA or placebo for 14 days. Their symptoms and mood states were recorded during the study and at a check-up 3 months later. Interpretation was based on intra-individual differences. DMSA-treatment resulted in an average increase in urinary mercury excretion by 65% and a decrease in blood mercury levels of 0.04 microgram/L/day. At the check-up after 3 months, urinary mercury excretion had returned to the pre-treatment level. No treatment effect of DMSA was apparent on subjective symptoms and mood state. One statistically significant treatment effect was noted-a decrease in fatigue-inertia in the DMSA-group-but there was no demonstrable correlation with increased urinary excretion or decreased blood concentration of mercury. Three subjects showed hypersensitive reactions, probably DMSA-specific, at the end of the treatment period. This placebo-controlled study provides no scientific support for diagnostic or therapeutic administration of DMSA for symptoms allegedly associated with chronic mercury exposition from dental amalgam fillings.