Medicine General af4163a5 Azotemia appears when residual GFR is: A 50% -80 % of normal B 20-50% of normal C 10 -20% of normal D < 5% of normal High-Yield Explanation Answer is B (20-50% of Normal): Azotemia appears in the stage of Renal Insufficiency when the residual renal function (Residual GFR) is between 20 to 50 percent of normal.