A THC metabolite concentration of 198 ng/ml is quite high, given that the test used was a GC/MS, which carries a cutoff threshold of 15 ng/ml. Since a quantitative value was provided, they did not perform a 50 ng assay screen since assays are a pass/fail endeavor and have no ability to yield a quantitative value.

As far as what can you do to prep, theres really nothing that you can do except try to dilute on the day of the U/A and hope for the best. Any fat-burning activities at this point will only release more THC metabolites into your bloodstream, which will end up in the urine and the sample cup.