MRCP2-1351

A 55-year-old woman is seen in your follow-up endocrinology clinic. She was referred by her GP a year ago after discovering a nodule in the front of her neck. Prior to this, she had experienced 6 months of worsening diarrhea and occasional flushing. She was diagnosed with a RET proto-oncogene mutation and underwent a thyroidectomy, followed by external beam radiotherapy. She is currently taking levothyroxine as her only medication.

What is the most effective test for monitoring the recurrence of this woman’s disease?