A 55-year-old woman presented with a several-month history of fatigue and weight gain. She reported that she felt puffy and swollen. She had difficulty buttoning the top button of her blouse because her neck was so large, but she reported no neck pain. Review of systems was positive for constipation, dry skin, and cold intolerance. On physical examination, a large goiter was found (Figure 235-1). Laboratory testing revealed an elevated thyroid-stimulating hormone (TSH) and a low free thyroxine (FT4) level, confirming hypothyroidism. The patient was started on levothyroxine.
Goiter that extends approximately 2 cm forward when viewed from the patient's side. (Reproduced with permission from Dan Stulberg, MD.)
Goiter is a spectrum of changes in the thyroid gland ranging from diffuse enlargement to nodular enlargement depending on the cause. In the United States, the most common etiology of goiter with normal thyroid function or transient dysfunction is thyroiditis.
Hypothyroidism is a condition caused by lack of thyroid hormone and usually develops because of thyroid failure from intrinsic thyroid disease. The most common cause of goitrous hypothyroidism is chronic lymphocytic (Hashimoto) thyroiditis.
Subclinical thyroid disease refers to abnormal laboratory values (elevated TSH and thyroxine level within the normal range) in a patient with no or minimal thyroid-related symptoms.
Worldwide, goiter is the most common endocrine disorder, with rates of 4% to 15% in areas of adequate iodine intake and more than 90% where there is iodine deficiency.1 Endemic goiter is defined as goiter that affects more than 5% of the population (Figures 235-2 and 235-3).
Most goiters are not associated with thyroid dysfunction.
The prevalence of goitrous hypothyroidism varies from 0.7% to 4% of the population.
Subclinical hypothyroidism is present in 3% to 10% of population groups and in 10% to 18% of elderly persons.2,3
The female-to-male ratio of goiter is 3:1, and 6:1 for goitrous hypothyroidism.
The annual incidence of autoimmune hypothyroidism is 4 in 1000 women and 1 in 1000 men, with a mean age at diagnosis of 60 years.4
Massive goiter in an Ethiopian woman who lives in an endemic area for goiters. Many adults have large goiters in Ethiopia where there is little iodine in their diets. (Reproduced with permission from Richard P. Usatine, MD.)
Goiter developing in a 12-year-old girl in an endemic area for goiters. (Reproduced with permission from Richard P. Usatine, MD.)
ETIOLOGY AND PATHOPHYSIOLOGY
Contributing factors for goiter are: