Evaluation of the thyroid nodule

Thyroid nodules are very common in the general population. The prevalence of palpable thyroid nodules is only approximately 4-7%, but the prevalence of ultrasound-detectable nodules is between 19 and 67% [1]. Twenty to forty-eight percent of patients with apparently solitary thyroid nodules palpated on physical exam will have additional sonographically detectable nodules [2,3]. Thyroid nodules are more common in women than in men by a ratio of about 4 to 1, and increase in frequency with age and with decreasing iodine intake 4]. Thyroid nodules are also more common in patients who have a history of head and neck irradiation, developing at a rate of about 2% per year compared with 0.1% per year in patients without a history of significant radiation exposure [5].