Approach to the Patient With a Thyroid Nodule
(See also Overview of Thyroid Function.)
Thyroid nodules are common, increasingly so with increasing age. The reported incidence varies with the method of assessment. In middle-aged and elderly patients, palpation reveals nodules in about 5%. Results of ultrasonography and autopsy studies suggest that nodules are present in about 50% of older adults. Many nodules are found incidentally on thyroid imaging studies done for other disorders.
Most nodules are benign. Benign causes include
Malignant causes include thyroid cancers.
Pain suggests thyroiditis or hemorrhage into a cyst. An asymptomatic nodule may be malignant but is usually benign. Symptoms of hyperthyroidism suggest a hyperfunctioning adenoma or thyroiditis, whereas symptoms of hypothyroidism suggest Hashimoto thyroiditis. Risk factors for thyroid cancer include
Initial evaluation of a thyroid nodule consists of measurement of thyroid hormones, specifically
If TSH is suppressed, radioiodine scanning is done. Nodules with increased radionuclide uptake (hot) are seldom malignant. If thyroid function tests do not indicate hyperthyroidism or Hashimoto thyroiditis, fine-needle aspiration biopsy is done to distinguish benign from malignant nodules. Early use of fine-needle aspiration biopsy is a more economic approach than routine use of radioiodine scans.
Ultrasonography is useful in determining the size of the nodule; fine-needle aspiration biopsy is not routinely indicated for nodules < 1 cm on ultrasonography or nodules that are entirely cystic. Ultrasonography is rarely diagnostic of cancer, although cancer is suggested by certain ultrasonographic or x-ray findings: