My Dr. wants me to do a 24 hour heavy metal challenge test with DMSA but I am hesitant for a few reasons. I know another poster (shanwill) recently posted about her caution with DMPS. But now after doing some research by Andy Cutler (supposedly the heavy metal guru) he says the challenge test has no diagnostic value! and that a hair analysis test is the best. I had a hair test in 1999 and I will get another now based on my research. I was already hesitant but now reading what I did from Cutler why would I waste $200? Unbelievable the amount of conflicting information for both heavy metals and FM/CFS at large, it is quite simply overwhelming. Below is from Andy Cutler: No. Challenge tests are of no diagnostic utility. Challenge tests do not tell you any more about body burden of mercury than an unchelated 24 hour urine mercury collection does. This is extremely well established in the literature for all numerate people. Since MD's as a rule are NOT numerate, and do NOT analyze the data in the papers they read about chelated and unchelated urine mercury production, they generally don't accept this. Kind of like someone arguing with you that 2+2 = 5 because they don't know how to add. If the same "challenge tests" that are used as diagnostic of mercury poisoning are applied to random people on the street who are healthy, most of them show up as "toxic," too. Lots of overtly mercury poisoned people who take the challenge tests do NOT meet the published criteria for being toxic, but they are still as a rule treated and get better from mercury detox. It is really pitiful to read stuff in the literature such as the statement in the paper on neurobehavioral impairment of dentists that says half the scores correlate slightly better with unchallenged mercury output and half slightly better with challenged mercury output and then have the authors not realize that what they said is that challenged and unchallenged mercury output are the same thing and statistical noise is controlling which fits better. There are even some papers that poisoned rats different ways so as to get different tissue distributions of mercury, and chelated them with DMSA and DMPS and determined where the mercury came from in the chelated urine - 75% from the kidneys with DMPS, about half with DMSA. The rest primarily from the bloodstream. These are NOT the target organs in chronic mercury intoxication so measuring what is in them isn't diagnostic. The challenge test is a pseudoscientific procedure (which most of the physicians using it do honestly believe in) to legitimize the diagnosis of mercury tox to the patient, physician, and possibly insurance carrier. It is a way to make things seem really technological and sophisticated because people are uncomfortable making the diagnosis on the basis of a physical examination and how the patient feels. The challenge test is a ritual to legitimize the diagnosis after it has been made on other grounds. Challenge tests that don't use timed urine samples are really silly since they are strongly influenced by how much water reabsorption there is in the kidney (your kidneys make about 125 quarts of pee a day, and then suck the water back up so you pee out 1 or 2 or 3. If you drink a bunch you may temporarily pee out urine at a rate of a quart per hour). Timed challenge tests give results completely predictable from the chelation formulae in my book and the unchelated urine mercury levels. Measure unchelated mercury level. Multiply by appropriate fudge factor. Get "challenge test" mercury level. No need for the challenge agent (or the risk or expense of the challenge test). Add to this that a very large number of doctor's offices mishandle the urine samples so that inaccurate results are obtained from both challenged and unchallenged samples (the creatinine level in the Doctor's Data report is there so you can check this - it should be pretty much the same every time, and you can calculate the number it should be from height). The "challenge tests" actually came from experiments done with people who worked in mercury using factories. These people had pre-chelator urine samples taken and then post chelator urine samples taken. Both the pre-chelator and post-chelator samples were vastly higher in mercury than is considered diagnostic for mercury tox by "alternative" doctors, yet all these people were quite healthy. The important factors in mercury intoxication are how sensitive the individual is, and how much is in their brain and internal organs. DMPS and DMSA challenge tests do not measure either of these. Have I belabored this enough? Andy Cutler PS since challenge tests are widely believed in, and even mentioned in some of the most recent medical texts, they may be worthwhile if needed to convince an insurance company or doctor that someone has mercury tox. But the test really does NOT provide useful diagnostic information even if an insurance company adjuster or physician is silly enough to think it does. I suggest using challenge tests only when necessary to convince such people.