Longstanding Asymptomatic Glycosuria with Emergent Ketonuria and Bilirubinuria: A Diagnostic Dilemma

A Case Report

Abstract

This case report presents a 53-year-old male with a longstanding history of asymptomatic glycosuria, first noted 10 years ago, and recently found to have new-onset ketonuria and bilirubinuria. His blood glucose levels remain normal, and previous laboratory assessments showed no abnormalities, supporting the diagnosis of isolated glycosuria. A similar finding of asymptomatic glycosuria is reported in his brother, raising the suspicion of familial renal glycosuria (FRG), a rare genetic condition often associated with mutations in the renal sodium-glucose co-transporter (SGLT2). This case emphasizes the significance of identifying familial renal glucosuria in patients presenting with isolated glycosuria, particularly when a relevant family history is present. Additionally, it underscores the diagnostic complexities arising from the emergence of ketonuria and bilirubinuria as new clinical feature. Recognizing FRG as a differential diagnosis can help avoid unnecessary testing and interventions, given its generally benign prognosis.