A study found that healthy adults on a high protein diet and taking creatine at an oral dose of 20 grams per day for 5 days plus 5 grams daily for 12 weeks showed no significant change in markers of renal function including creatinine clearance, urine urea, serum urea, albuminuria, proteinuria, and serum electrolytes between baseline and after 12 weeks as well as when compared to controls (21).
Safety of creatine supplementation, kidney function, and case reports:
Yoshizumi WM et al reported that data in 12 relevant articles and case reports, creatine supplementation appears safe when used by healthy adults at the recommended loading (20 gm/day for five days) and maintenance doses (15).