Part of “CHAPTER 39 – THE THYROID NODULE“

The prevalence of thyroid nodules must be considered from several perspectives. As many as 1.5% of adolescents may have palpable thyroid nodules, and the frequency increases linearly with age.11 In large population studies, nodules have been reported in 3% to 7% of adults, with a 5:1 female/male ratio. Many of these reports have failed to distinguish solitary nodules from multiple thyroid nodules; on histologic examination, many single, palpable nodules are found to be within a multinodular thyroid gland. Some autopsy series report thyroid nodules in more than one-half of consecutive cases, although many may be small, nonpalpable lesions, and multinodularity occurs in up to 75% of these.1,3,4 High-resolution ultrasonography has identified nodules in 13% to 40% of patients undergoing evaluation for nonthyroidal problems.14,15,16 and 17 Thus, a discrepancy exists between the true prevalence of thyroid nodules and the number that are apparent by physical examination. Normally, nodules must approach 1 cm in diameter to be consistently recognized on palpation, although this size varies according to the location of the nodule within the gland and the anatomy of the neck. Nonpalpable nodules, such as those incidentally seen on ultrasonographic studies for nonthyroidal neck evaluation, are of unknown clinical significance.