Changing trends in thyroid practice: understanding nodular thyroid disease.

OBJECTIVE: To describe changes that have occurred between 1952 and 2002 in the evaluation and management of nodular thyroid disease.
METHODS: A 30-year personal experience, institutional contributions, and the related published literature on evaluation of thyroid function and evolving strategies for management of thyroid nodules are reviewed.
RESULTS: Triiodothyronine (T(3)) was discovered in 1952, and measurement of plasma thyroxine by a competitive protein-binding technique became available in the 1960s. Late during that decade, the first radioimmunoassay for thyroid-stimulating hormone (TSH) was described, modified, and then used in clinical practice until the mid-1980s, when the more sensitive TSH assays became widely available. T(3) determination by radioimmunoassay was introduced early in the 1970s. Currently, sensitive thyroid function tests can detect early disease. In the general population, thyroid nodules have a prevalence higher than 50% after age 65 years, affecting more than 100 million people in the United States. Two important developments influenced thyroid nodule evaluation and management-- fine-needle aspiration (FNA) biopsy and ultrasonography. Because FNA biopsy has emerged as the most accurate test for nodule diagnosis, it has decreased the need for scanning and for thyroidectomy and thereby is likely to reduce health-care costs by more than $500 million annually in the United States. Thyroid ultrasonography is the imaging method of choice for evaluation of thyroid gland structure. Management of cytologically benign thyroid nodules remains controversial.
CONCLUSION: TSH seems to be only one of many factors in pathologic thyroid growth. FNA, because of its diagnostic accuracy, should be the initial procedure used in nodule evaluation.