BUN and creatnine w lithium

My lithium level is .53. I just started it.

My egfr went from 90 to 75 and creatnine from 1.01 up to 1.18 and BUN from 12 to 20.

I haven’t followed up with my doctor yet and because the lithium is helping me, I’m worried that I’m gonna have to go off it because obviously I don’t want it to hurt my kidneys. This all could mean I was just dehydrated, but I’m wondering if anybody has had a similar experience where these tests come back still within the normal range but changed in the wrong direction.