21st February 2025

A 72-year-old man with a recent diagnosis of small cell lung cancer is seen for a routine oncology appointment and reports a 1-month history of weakness, muscle aches and a change in his gait.

A 72-year-old man with a recent diagnosis of small cell lung cancer is seen for a routine oncology appointment and reports a 1-month history of weakness, muscle aches and a change in his gait. In particular, he has noticed that his weakness often improves after a short period of exercise before worsening again. On further questioning, he reports some blurring of his vision and dry eyes and mouth.

Which blood test would be most useful in identifying the cause of his symptoms?

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