Laboratory and Clinical Assessment of Hyperthyroidism

Abstract

A 35-year-old woman presents for evaluation of a thyroid nodule and abnormal thyroid function tests. Eight months after delivering her baby, she noted a lump on the left side of her neck. She has also complained of feeling more tired and anxious, but she has not been sleeping well at night since her baby was born. She is no longer breast-feeding. She has never been exposed to radiation to her head or neck. Her weight has remained stable. She denies compressive symptoms such as dysphagia or breathing diffi culties related to this nodule. Her grandmother had thyroidectomy years ago for thyroid cancer but is doing well without recurrence. Thyroid function tests obtained at her primary doctor's offi ce show TSH of 0.03 mIU/L, free thyroxine of 2.2 ng/dL (normal 0.8-1.8 ng/dL), and total T3 of 264 ng/dL (normal 80-190 ng/dL).Examination shows a slightly anxious woman, with a blood pressure of 126/60 mmHg and pulse of 110 bpm.Eyes: Positive stare and lid lag; no conjunctival injection, chemosis, or proptosis; and extraocular movements are normal. Neck exam shows an enlarged left lobe with a palpable 3.5 cm fi rm nodule that moves freely with swallowing. Right lobe is mildly enlarged, but without discreet nodules. There is no palpable neck lymphadenopathy. There is a very slight tremor of her extended fi ngers. No clubbing. Her deep tendon refl exes are normal. Remainder of her exam is noncontributory.What is the next best step in the evaluation of this patient's complaints?