In patients with chronic kidney disease, antibiotic dosing should be adjusted primarily based on which measure of renal function?

• A. Heart rate
• B. Serum calcium
• C. eGFR
• D. Serum sodium

Answer: (C)

In chronic kidney disease, how quickly the kidneys clear drugs dictates how we should dose antibiotics. The best single measure to guide this is the estimated glomerular filtration rate (eGFR). eGFR estimates how well the kidneys are filtering blood and, unlike some other values, correlates closely with the actual drug clearance for most renally excreted antibiotics. It’s also adjusted for factors like age, sex, and body size, making it more reliable than a crude serum creatinine value alone, which can be influenced by muscle mass and nutrition. By using eGFR to tailor dose or dosing interval, we minimize drug accumulation and toxicity while maintaining effective exposure. Serum calcium, serum sodium, or heart rate do not reflect renal excretory capacity and are not used to adjust antibiotic dosing.