Final answer:
Acute renal failure (ARF) does not always result in a return of renal function within weeks, as recovery depends on the severity of the condition, the cause, and the promptness of treatment. While some causes of ARF are reversible, others can lead to chronic kidney disease if kidney function does not recover.
Step-by-step explanation:
The statement 'Renal function always returns in weeks with acute renal failure' is false. Acute renal failure (ARF), now more commonly referred to as acute kidney injury (AKI), is a sudden loss of kidney function over a period of days to weeks. ARF can have a variety of causes that are classified into pre-renal, renal, and post-renal categories. While some patients can recover kidney function, the recovery is not guaranteed and depends on various factors such as the severity of the injury, the underlying cause, and promptness of treatment.
The time for recovery in acute renal failure can be variable, and in some cases, the kidneys may not recover at all, resulting in chronic kidney disease (CKD). Therefore, it's important to assess each case of ARF individually with proper diagnostic measures like serum creatinine levels, urine output, and sometimes renal imaging like ultrasound or nuclear medicine scans.