What is the most likely interpretation of her thyroid function test results?

A 36-year-old woman was referred to the endocrine clinic with abnormal thyroid function tests. She gave a 3-year history of increased sweating and anxiety following an assault and, initially, her symptoms had been attributed to post-traumatic stress disorder.

Investigations:

serum thyroid-stimulating hormone (TSH)3.1 mU/L (0.4C5.0)

serum free T429.8 pmol/L (10.0C22.0)

serum free T33.5 pmol/L (3.0C7.0)

What is the most likely interpretation of her thyroid function test results?
A . assay interference
B . factitious thyrotoxicosis
C . resistance to thyroid hormone
D . TSH-secreting pituitary adenoma
E . use of combined oral contraceptive pill