12th April 2024

A 63 year old male presents with a three day history of coughing purulent green sputum accompanied with mild shortness of breath and generalised chest pain.

A 63 year old male presents with a three day history of coughing purulent green sputum accompanied with mild shortness of breath and generalised chest pain. He also reports reduced eating and drinking but no weight loss. His medications include, as required, diazepam and regular phenytoin; however, he admits that he often misses doses. Chest X-ray demonstrates a right lower lobe consolidation. His blood and urine results are shown below:

Based on the investigations and history gathered, what is triggering the hyponatraemia? 

Select the SINGLE most appropriate option from the list below. Select ONE option only.