The Care Team Is Considering the Use of Dialysis in a Patient

The care team is considering the use of dialysis in a patient whose renal function is progressively declining. Renal replacement therapy is indicated in which of the following situations?

A) When the patients creatinine level drops below $1.2 \mathrm{mg} / \mathrm{dL}(110 \mathrm{mmol} / \mathrm{L})$
B) When the patients blood urea nitrogen (BUN) is above $15 \mathrm{mg} / \mathrm{dL}$
C) When approximately $40 \%$ of nephrons are not functioning
D) When about $80 \%$ of the nephrons are no longer functioning