Can grave's disease affect kidney function?

Graves' disease. If left untreated or if a patient goes into a "thyroid storm" there can be side effects that can lead to renal damage, but overall it tends not to be a long term or chronic side effect of the overall condition.
Not usually. Very rarely, hyperthyroidism from graves' can be so severe that it causes many organs to malfunction. Usually, however, kidney function stays normal. More common problem areas are the heart, the bones, and the brain. Graves' can also cause problems for the eyes, causing double vision or making them bulge out more than usual.