Practice question from Creatinine Clearance & Dose Adjustments

A 58-year-old male (5'10", 85 kg, SCr 1.6 mg/dL) is prescribed gentamicin. His IBW is 73 kg. What weight should be used for dosing calculations? A. 73 kg (ideal body weight) B. 85 kg (actual body weight) C. 78 kg (adjusted body weight) D. 79 kg (average of IBW and ABW) E. 80 kg (rounded actual weight)

Answer

A

Explanation

The patient's actual weight (85 kg) is only 16% above IBW (73 kg), which is less than the 30% threshold for using adjusted body weight. Therefore, use IBW (73 kg) for both CrCl calculation and gentamicin dosing. AdjBW is only used when actual weight exceeds IBW by more than 30%.

More questions from NAPLEX Mastery Roadmap (High-Yield + Weakness-Driven)