1st April 2022

A 58-year-old female presents to her GP with symptoms of a sour/bitter taste in her mouth associated with consumption of food

A 58-year-old female presents to her GP with symptoms of a sour/bitter taste in her mouth associated with consumption of food. This has developed over the past month. She is otherwise fit and well on no other regular medications. Examination is unremarkable. 

Select the SINGLE most appropriate first-line investigation option from the list below. Select ONE option only.