23rd May 2025

A 40-year-old male presents to GP after noticing he has been going to the toilet frequently due to producing large amounts of urine despite no obvious changes in how much he drinks during the day.

A 40-year-old male presents to GP after noticing he has been going to the toilet frequently due to producing large amounts of urine despite no obvious changes in how much he drinks during the day. This also wakes him up at night. He has also been feeling very thirsty. Past medical history is notable for a recent transsphenoidal surgery for a non-functioning macroprolactinoma. 

What investigations would lead to a diagnosis of the most likely pathology?

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