Chris Kresser: I haven’t. I know that DUTCH originally developed the dried urine tests. We can check with Mark Newman from Precision Analytical to see what there might be there in terms of difference and get back to you.
From Mark Newman: Their test is a pretty close to our DUTCH Complete in terms of analytes. They do two OATs and don’t do 8-OHdG. I’m really not sure what sort of methods they are using. I think it says a lot that we have published serum correlation data and 24-hour urine correlation data. I’m not suggesting their testing shows poor correlation, but it’s definitely something that has to be established and preferably published to increase confidence. I think it’s a bit of an advantage for us that our sole focus is on this test because it helps us to look at every angle of the test both analytically and clinically. The only thing I’ve heard in terms of a preference is the fact that they sell theirs a little cheaper than ours. Ours is probably a little more expensive due to the fact that we are using more diverse analytical methods. We test the sex hormone metabolites on the GC-MS/MS and have separate assays (on the LC-MS/MS) for melatonin, 8-OHdG, OATs, etc. Again, I don’t have a great handle on the actual quality of their assay. It’s difficult to tell without published data. We have compared a few samples, but they have been unwilling to do so in a cooperative way, so it is limited to a few samples a year. Overall, the general correlation is decent between the two methods. The analytical comparison is a little better with ZRT’s methods.
Lastly, I don’t think they are mixing the urine measurements with the salivary CAR, which is my favorite aspect of what we’re doing now.
I can’t entirely speak to the specifics of what they are doing, and I don’t mean to speak negatively about what they are doing. I know this specific analysis is a fairly complex method that we’ve been perfecting for over a decade, and I think there is an advantage to using a lab highly focused on this work. I hope that helps.