Case Presentation: A 59-year-old female with recently diagnosed perihilar lung mass and liver lesions presented for evaluation of painless jaundice and transaminitis. Initial laboratory studies revealed a sodium of 129 mOsm/kg, elevated bilirubin, alkaline phosphatase, lipase, and liver enzymes. Initial hyponatremia workup showed a serum osmolality of 279 mOsm/kg, urine osmolality of 118 mOsm/kg, and [...]