Originally posted by urge2kill
I mean you could give then apple juice and pass since they'll be no presence of drugs.
But that's why they'll test for a number of things like: hormones, pH, creatinine, specific gravity, drug metabolites and diuretics. Lets say you drank a bunch of liquids before your test, this extra water will dilute your sample so whatever drugs you may have taken show up in small amounts. So that's why they'll measure creatine levels, because there's a specific level of it in your urine. If your creatine levels are low, then it's proof that your urine is diluted. Synthetics are a blend of water, urea, creatine and whatever else to make it look like your urine is on drug free and on the up and up.
The only thing they can't do is the human hormones, the synthetics wont have any of them. I'm speculating here but I'm almost positive that's how they caught Silva.