the test was negative for urine. problem is, lab doesn't know if it was a false negative because the urine concentration (seen via the specific gravity) is too low.

also your creatinine (a muscle breakdown product) is below normal.

if they're requiring that you retest, you can try drinking some creatine the night before and morning of the test. the breakdown product of creatine is creatinine. worst case scenario, you'll have too much and you can just tell them you went to the gym and ran a few miles the morning of the exam. vigorous exercise can increase its levels too, but i wouldn't suggest you exercise though because doing that might release stored THC from your adipose tissue.

or you could do the simple thing and just sub it in your repeat visit. i've been lucky enough to never have to have done that in the past but i'm gonna have to make my first attempt in a few weeks. lots of info on these boards though.