Fiona, I have had three different tests - one was a challenge test in which I was given a chelator and had a 24 hour urine done, and then my mercury levels were measured. Another was a hair analysis for mercury. And most recently, my dr. gave me a 24 hour urine test for porphyrins. I get the results this coming week. Just doing a blood mercury or a urine mercury will not give you much information from everything that I have read. If you go to the Huggins website, they have a phone # - maybe they can give you a referral source in your area - or even a dr. that you can do a phone consult with somewhere else. You should also get the books that Laura mentioned above. Hope this helps.