What GFR level indicates kidney disease?

This is because a GFR level less than 60 mL/min/1.73m2 is considered below normal and can indicate kidney disease. GFR levels above this range (options A, C, and D) are considered within the normal range and do not indicate kidney disease. It's important to note that a GFR level alone is not enough to diagnose kidney disease, as other factors such as age, gender, and medical history also play a role. Therefore, it's important to consult with a doctor for a proper diagnosis and treatment plan.