My sodium test result is 134 ( 137-148 ) mmol/l it's below normal and bicarbonate (sodium bicarbonate) is 21 ( 24-30 ) and my uric acid is 150 ( 200-425) umol/l why ?

See your doctor. : Without the benefit of a history and exam, it is difficult to interpret these isolated lab values. May want to have cortisol level checked. These results are not alarming, but i recommend further evaluation by a nephrologist.

Limit workup: Low uric acid never means anything. The tiny sodium and bicarb deviations may be lab artifacts, suitable to be rechecked during your next health maintenance visit. If you feel well, i would not fault your physician for doing nothing whatever.