Optimizing Inpatient Phototherapy in Adult Crigler-Najjar Syndrome Type 1: A Practical Framework for Acute Hyperbilirubinemia Management.

Crigler-Najjar syndrome type 1 (CN1) causes complete UGT1A1 deficiency, lifelong severe unconjugated hyperbilirubinemia, and persistent risk of bilirubin-induced neurologic dysfunction. We present a 21-year-old woman with genetically confirmed CN1 who developed acute-on-chronic hyperbilirubinemia to 30 mg/dL during hospitalization for Shigella enteritis when her home high-intensity phototherapy system was unavailable. Systematic optimization of inpatient phototherapy using multiple high-irradiance units with simultaneous dorsal and ventral coverage produced a 7.5 mg/dL bilirubin reduction within 12-18 hours, deferring planned therapeutic plasma exchange entirely. This case highlights phototherapy inadequacy as a correctable, underrecognized driver of acute decompensation in hospitalized adult CN1 patients.