Creatinine levels vary depending on age, ethnicity, body size and muscle mass. Normal creatinine ranges are 0.72 – 1.25 mg/dL for adult males and 0.57 – 1.11 mg/dL for adult females.
Normal GFR is more than 90 for adults. GFR declines with age, even in the absence of kidney disease. Values between 60 and 89 may indicate kidney disease. Values less than 60 for more than 3 months occur during moderate-to-severe chronic kidney disease.