Case: Investigations
Patient’s laboratory workup was significant for plasma hypoosmolality
(224 mOsm/kg), inappropriate urinary concentration for the given plasma
osmolality (405 mOsm/kg), and elevated urinary sodium excretion (83
mmol/L) (Table 2). The patient had normal cortisol and thyroid function
tests. A CT scan of the head and chest radiographs showed normal
findings. Our patient denied any increased water intake. A review of the
patient’s home medications revealed that she was prescribed
chlorthalidone and carvedilol for hypertension for the past year.