Source: Richard Glickman-Simon, MD, Assistant Professor, Department of Public Health and Community Medicine, Tufts University School of Medicine, MA

The thyroid gland is located in the neck anterior trachea between the cricoid cartilage (above) and the suprasternal notch (below) (Figure 1). It consists of a right and left lobe connected by an isthmus. The isthmus covers the second, third, and fourth tracheal rings, and the lobes curve posteriorly around the sides of the trachea and esophagus. The normal gland, weighing 10 - 25 g, is usually invisible on inspection and often difficult to palpate. A goiter is an enlarged thyroid from any cause. In addition to assessing its size, it is important to palpate the thyroid for its shape, mobility, consistency, and tenderness. A normal thyroid is soft, smooth, symmetrical, and non-tender, and it slides upward slightly when swallowing. Symmetrical enlargement of a soft, smooth thyroid suggests endemic hypothyroidism due to iodine deficiency or one of two prevalent autoimmune disorders: Graves' disease or Hashimoto's thyroiditis. Thyroid nodules are common and usually incidental; however, 10% of thyroid nodules turn out to be malignant. They may be single or multiple, and are most often firm and non-tender. A tender, symmetrical goiter typically indicates thyroiditis.

Figure 1. Anatomy of the thyroid gland. Illustration of the location and anatomy of the thyroid gland with respect to the neck structures.

Thyroid disease rarely manifests as a palpable goiter in isolation. Thyroid hormones serve to maintain homeostasis primarily by stimulating cellular metabolism throughout the body. Thus, hypo and hyperthyroidism are associated with a range of symptoms and physical findings (Table 1). It is important to note that goiters may be euthyroid (normal thyroid hormone levels), hyperthyroid, or hypothyroid. Headaches or visual disturbances may suggest a secondary thyroid disorder due to a pituitary adenoma

Table 1. Symptoms and physical findings for hypo- and hyper-thyroidism.