Hello just wondering what is the normal range/level of creatinine of a 3 yrs old boy that has only one kidney? his creatinine level went up to 0.45

Here are some...: Please ask his doctor who likely knows his serial serum creatinine for comparison and his clinical profile for correlation. At 3, S creatinine may be 0.2-0.5 mg/dl reflecting his lean muscles, hydration, & solitary kidney. It is right to just use one report to tell if kidney works well or not at this time. So, asking his pediatrician is the most reasonable thing to do. All the best to his health