What laboratory tests and imaging studies should be included in the workup of a palpable thyroid nodule?
What should be included in the workup of a palpable thyroid nodule?
About 5% of women and 1% of men have palpable thyroid nodules, and high-resolution ultrasonography may reveal nodules in up to two thirds of adults. Thyroid cancer is diagnosed in more than 20,000 patients each year in the United States.1 Primary care physicians are often the first to detect thyroid nodules. They are then faced with the question: are these nodules benign or malignant?
Recently, the American Thyroid Association updated its guidelines for the diagnosis and management of thyroid nodules and cancer.1 Included are questions that are relevant to primary care. Here I present several of the questions that physicians most often ask about the evaluation of thyroid nodules. Refer to the guidelines for answers to more specific questions that may arise in practice.
Which laboratory tests and imaging studies are recommended?
Physical examination remains highly important. The palpation of a nodule should always lead to careful examination of surrounding cervical lymph node groups.
If the nodule is larger than 1.5 cm, measure the patient's serum thyroid-stimulating hormone (TSH) level. If the TSH level is low, order a radionuclide scan to determine whether the nodule is "hot, warm, or cold." If the nodule is "hot" (that is, functioning), no further workup is necessary because cancer is highly unlikely.
Ultrasonography is indicated if palpation suggests the presence of one or more nodules. This study is particularly helpful for evaluating smaller nodules.
What is the role of fine-needle aspiration?
Fine-needle aspiration (FNA) remains the best method to evaluate nodules and to determine whether they are malignant.
Is medical therapy recommended for benign nodules?
The controversy surrounding thyroid hormone suppression of benign nodules has been settled. Routine suppression is no longer recommended.
How are thyroid nodules best managed in pregnant women?
FNA can be performed safely during pregnancy; however, if the TSH level is suppressed, nodules can be aspirated after delivery (because they are rarely malignant in this setting). If the results of the FNA are consistent with a malignancy, monitor the nodule with ultrasonography. If the nodule increases in size by 24 weeks' gestation, surgery should be performed.
The American Thyroid Association Guidelines Task Force. Management guidelines for patients with thyroid nodules and differentiated thyroid cancer.