The benefits of pre- and post-challenge urine heavy metal testing: Part 1.

Measuring urine heavy metals is an accepted method for assessing the presence of these toxins in an individual. A random sample (without a flushing agent) is excellent for showing current exposures because it reflects the level of heavy metals in the bloodstream during the hours immediately before bladder voiding. A sample taken after using a heavy-metal-mobilizing agent provides a reflection of total body burden. By utilizing both pre- and post-flush testing, the clinician gains information that cannot be acquired by other means, including identification of current exposures to lead and mercury - critical for proper treatment. Conducting pre-flush testing is also currently the clinician's only means of identifying cadmium toxicity. In addition, pre- and post-challenge testing allows the clinician to identify which chelating agent is the most effective for the patient; and if oral agents are employed, possible absorption problems can be identified. Since these benefits are not realized with only post-flush testing, it is recommended that clinicians test both before and after a chelation challenge.