American Board of Internal Medicine (ABIM) Certification Practice Exam

How many days after starting aminoglycoside therapy does serum creatinine typically rise?

1. 1-3 days

2. 5-10 days

3. 10-15 days

4. More than 15 days

The correct answer is: 5-10 days

The rise in serum creatinine after initiating aminoglycoside therapy is typically observed between 5 to 10 days. This timeframe aligns with the pharmacokinetics of aminoglycosides, which include gentamicin, tobramycin, and amikacin. These medications can lead to nephrotoxicity, particularly when used at higher doses or for extended durations. The kidneys may take several days to exhibit signs of injury, which is why monitoring serum creatinine within this period is crucial for early detection of potential renal impairment. A rise in serum creatinine within 1-3 days is less common, as nephrotoxic effects generally manifest after a longer duration of therapy. Similarly, waiting for a rise beyond 10 days is also unusual, as most instances of renal impairment from aminoglycosides can be detected within the 5 to 10-day window. Monitoring during this timeframe is essential for ensuring patient safety and appropriate management of therapy.