American Board of Internal Medicine (ABIM) Certification Practice Exam

What is a common complication of topiramate related to kidney health?

1. Nephrotoxicity

2. Kidney stones

3. Renal failure

4. Hyperkalemia

The correct answer is: Kidney stones

Topiramate is known to cause metabolic acidosis and the formation of kidney stones, particularly calcium phosphate stones. This complication is primarily linked to the drug's ability to inhibit carbonic anhydrase, which can lead to an increase in urinary calcium concentration. The elevated levels of calcium in the urine can precipitate and form stones, resulting in renal complications such as flank pain, hematuria, or obstruction. It's noteworthy that this risk is particularly relevant in individuals who are also dehydrated or have other predisposing factors for stone formation. Understanding the mechanism by which topiramate affects the kidneys is crucial for clinicians. While nephrotoxicity is not generally associated with topiramate, as it does not exhibit direct toxic effects on renal parenchyma, the increased risk of nephrolithiasis should be closely monitored. Additionally, conditions like renal failure and hyperkalemia are not common complications directly linked to topiramate use. Monitoring hydration status and advising patients on dietary modifications can help mitigate the risk of stone formation during treatment with topiramate.