[Hyponatraemic delirium as an early symptom of small-cell bronchial carcinoma]

In the psychiatric clinic, delirious states are rare as the first symptoms of paraneoplastic syndrome, and the aetiology can only be clarified by consequent differential diagnostic efforts. We report the case of a 49-year-old man who was admitted to our psychiatric unit with delirium. Laboratory investigations showed hyponatraemia, serum hypo-osmolality, and urine hyperosmolality characterising the syndrome of inappropriate antidiuresis (SIADH). As a paraneoplastic syndrome, SIADH is most frequently associated with small-cell lung cancer (SCLC). Whereas chest X-ray was negative, chest CT scan and bronchoscopy including histology revealed a SCLC at an early stage of limited disease. Early oncological therapy made it possible for our patient to return to work with a satisfactory quality of life. Twenty-one months after first admission, he died as a result of recurrent SCLC metastases.