Don't know. Also had mine checked. Know of others for whom the same is true. Always nothing! When, obviously, something causes it! Have always suspected there's some yeast involved. When I've taken olive leaf extract, the bubbles have disappeared. Among other "anti's," o l e is anti-fungal (anti-yeast). However, did not return after I stopped the o l e. Just guessing, but yeast causes fermentation (little critters called fermens do their life's work, which causes fermentation), which causes bubbles to rise in booze, bread, in warm water in a cup. If you find out for sure, let us know!
my semen always coming with urine with bubbles. i'm kindly asking you, how to solve this problem.