A 37-year-old woman presented with a 2-year history of increasingly frequent flushing episodes. She described alternating loose bowel motions and constipation. She had also noted menstrual irregularity. She had no respiratory symptoms. She denied headache or chest pain, but complained of palpitations.
On examination, she appeared well. Her blood pressure was 128/82 mmHg.
Investigations:
serum thyroid-stimulating hormone0.8 mU/L (0.4C5.0)
What is the most appropriate next investigation?
A . fasting plasma gut hormones
B . plasma metanephrines
C . serum gonadotrophins
D . urinary 5-hydroxyindoleacetic acid
E . urinary metanephrines
Answer: C