Gastritis/gallbladder issues. Pain in gut. Labs show BUN 28, Creatine Bun ratio 30.30.told to drink water. Should I worry? Gallbladder surgery soon.

Elevated BUN/cr. Would not worry. Likely due or dehydration as most people do not drink enough fluids. If other labs like creatinine alone are OK( which it appears to be as BUN is 28 and the ratio is 30 so creatinine has to be < 1 ) and liver functions are OK , don't worry . BUN is slightly higher in older individuals. . Good luck with surgery.

https://labtestsonline.org/understanding/analytes/bun/tab/faq/