Re: Care of patients who are worried about mercury poisoning from dental fillings.

INTRODUCTION Public concern about adverse health effects from mercury exposure from dental amalgams remains a high-profile issue. Patients with nonspecific neuropsychiatric symptoms may incorrectly attribute their complaints to mercury poisoning, and some alternative medical providers diagnose mercury toxicity using nonvalidated tests or without testing at all. CASE REPORT We report the case of a 37-year-old female who was referred to our outpatient medical toxicology clinic by her family medicine physician after a wellness doctor involved in her care ordered a dimercaptopropanesulfonic acid (DMPS) challenge urine study that revealed an "elevated" mercury level. DISCUSSION The use of postchelator challenge urine testing to diagnose mercury poisoning has not been validated. Use of such tests may cause falsely elevated urine mercury levels resulting in misdiagnosis of mercury poisoning and unncessary, expensive, and potentially dangerous chelation therapy. CONCLUSION Family medicine physicians may encounter patients who are concerned about mercury poisoning after undergoing postchelator challenge urine testing. In patients with a low suspicion for mercury toxicity, reassurance is adequate. In patients with moderate to high suspicion for mercury toxicity, a validated test for mercury, such as a 24-hour urine mercury level, or referral to a medical toxicologist is the most appropriate approach.