A Patient with Acute Liver Injury after Sulfamethoxazole/Trimethoprim Treatment for Pyelonephritis

Background: Sulfamethoxazole/Trimethoprim is a commonly used drug in a variety of clinically indicated scenarios, but it is not without side effect. Case-reports have stated that adverse reactions secondary to Sulfamethoxazole/Trimethoprim can present very early in the course of treatment, especially in patients who have a higher predisposition. Thus, the burden is placed on the clinician to be wary of these side effects and be able to recognize them in the correct clinic scenario. Objective: To discuss the risk of developing cholestatic hepatic dysfunction secondary to treatment with sulfamethoxazole/trimethoprim. Methods: We present the history, physical findings, laboratory investigations, and clinical course of a 47-year-old African-American female who developed cholestatic hepatic dysfunction after treatment with sulfamethoxazole/trimethoprim for pyelonephritis. Results: Drug-induced liver injury is a rare complication of sulfamethoxazole/trimethoprim therapy and only 20% of cases are secondary to cholestatic hepatic dysfunction. Our patient, who had been on sulfamethoxazole/trimethoprim for 7 days for pyelonephritis, presented to our hospital with a clinical picture consistent with hepatic injury; her laboratory investigations were noteworthy for an elevated white blood cell count, platelet count, and elevated transaminases, along with alkaline phosphatase levels greater than 2 times the upper limit of normal. Promptly following the discontinuation of sulfamethoxazole/trimethoprim, our patient improved clinically and her liver enzymes down-trended during the course of her hospital stay. She returned to normal at her 4 month follow up, thus confirming the diagnosis of cholestatic hepatic dysfunction secondary to sulfamethoxazole/trimethoprim. Conclusion: Cholestatic hepatic dysfunction is a form of drug-induced liver injury and a rare complication of sulfamethoxazole/trimethoprim treatment. The majority of cases resolve following discontinuation of the offending medication. However, a small percentage of patients may progress to liver failure and ultimately require liver transplantation. Clinicians should be aware of these risks to avoid delaying the discontinuation of sulfamethoxazole/trimethoprim.