they can't tell your blood levels(as it is urine), but they could tell most of what you are/have used that the metabolites or active drug is in your system... that particular test, if you zoom on the pic, you can read what it can test for... anadrol, deca(any 19nor really), test, epitest..there's a bunch on there.. I would have to look at the link to see all the metabolites... but rest assured, it covered most basic structures of steroids...(it tests for a whole shitload of metabolites... these are linked to particular structures.. they don't have to test for every drug.. just metabolites of structures)... that being said, there are two compounds that will block the excretion of metabolites in urine.. they are Probenecid and Anturane.. they are gout medicines(though they have other uses)...don't take those to try to retain steroid in your system!! you could die!!! they should only be used to pass a URINE test for juice... that test doesnt say it tests for either of those masking agents..