Its very concerning. My renal function was just under the okay line, I called my Pdoc, he told me to stop Lithium and we would retest in a week. I did and the following tests showed everything looked good. I did go back on slowly and had blood tests weekly for at least 2 months ( My request). I did decided to go off Lithium lil bit down the road. I was concerned of possible long term renal damage.

Are you drinking enough fluids daily? If your not getting enough it can show up in the renal testing.

Let your Pdoc know.