Isotretinoin-Induced Proteinuria: An Underrecognized but Potentially Common Complication

Introduction: Isotretinoin is widely prescribed for dermatological conditions, particularly acne vulgaris. However, evidence regarding its renal effects remains conflicting. In animal studies, isotretinoin has been shown to reduce proteinuria and preserve glomerular function. In contrast, human case reports have documented adverse renal outcomes, including acute kidney injury, renopulmonary syndrome, and nephrotic syndrome. The overall incidence and significance of proteinuria remains unclear. Case Description: We report a case of isotretinoin-associated proteinuria in an otherwise healthy 18-year-old male. The patient, with no significant medical history and weighed 53kg, began oral isotretinoin (30mg 3 times per week) for acne in mid-2023. During routine health screening for national service in January 2025, he was found to have 4+ proteinuria on two separate urine dipsticks, despite being asymptomatic and showing no signs of nephrotic syndrome. He was referred to the nephrology clinic for further evaluation. By the time of his consultation, he had discontinued isotretinoin for two months. Initial investigations revealed unremarkable autoimmune and hepatitis screens, a urine protein-creatinine ratio of 0.09, and normal renal ultrasound findings. He later resumed isotretinoin at a higher dose (30mg daily), and four months later, repeat testing showed an increase in 24-hour urine protein of 0.48 g, with preserved renal function and normal serum albumin. Isotretinoin was discontinued, and proteinuria resolved on subsequent follow-up. Discussion: Current reports of renal complications associated with isotretinoin typically involve symptomatic patients, with adverse effects identified at the time of clinical presentation. However, the true incidence and long-term consequences of asymptomatic renal complications remain unclear. This case highlights the potential for reversible, dose-related, asymptomatic proteinuria associated with isotretinoin, emphasizing the need for greater clinical awareness and routine monitoring during treatment.