My father is 60 yrs old. He had low grade non muscle invasive bladder cancer 2yrs ago. He had been given mitomycin 40 for 6wks.no recurrence since then. 3months checkup for 1yr,then after 6month.Now he has been told to come to check up after 1yr.Everytime Dr. told us to bring serum creatinine test report before cystoscopy.during last check up on 5th September his creatinine rise 1.31mg/dl but no recurrence of tumor.since then I made a low salt diet for him and keep him hydrated.Today on 2nd November I test his blood again.creatinine 1.16mg/dl,serum urea 24mg/dl,potassium 3.9mEq/l,sodium 133,hemoglobin 13.6. Should we be worried? What should be our next step?