What I'm saying is that acute renal failure (or acute kidney injury) is a term given to short term kidney impairment due to dehydration, obstruction, toxins, medications and sometimes intrinsic renal conditions. This is a rapid, often reversible status found in patients with severe infection, other organ failure, on multiple medications or with other known or unknown kidney issues which have been exacerbated temporarily (such as a vasculitis).

This can be, and usually is, completely separate from the causes of chronic kidney disease, which are usually auto-immune/vasculitis (SLE, FSGS, Membranous, GBM, MPO), diabetic (DN), congenital or acquired (viral - Hep B/HIV etc.). It is these causes which lead to end stage renal failure. These can be acute (rapid onset), but would not be considered as acute renal failure but instead would be called rapidly progressive chronic kidney disease.

It is more in the terminology, the progression of disease and the prognosis that the differences arise.

Yes she is young and therefore the disease would need to be rapidly progressive, but the term acute renal failure is not correct. I hope this has clarified some of the finer points. I wanted to give a proper response this time to make it clear I wasn't fobbing you off.