Nontoxic diffuse goiter is thyroid enlargement unrelated to hypothyroidism, hyperthyroidism, inflammation or neoplasia.
Etiology is usually unknown. Some known causes include iodine deficiency, iodine excess, goitrogen ingestion, autoimmune disorders, thyroid hormone production defects and certain medications.
It is usually asymptomatic.
Symptomatic patient may present with painless neck swelling, cosmetic complaints, shortness of breath, sudden increase in goiter size with pain due to hemorrhage, larger goiter causing obstructive signs eg dysphagia, choking sensation and Pemberton's sign.

Diagnosis of exclusion to rule out goiter due to hypothyroidism, hyperthyroidism, autoimmune thyroiditis, invasive fibrous thyroiditis, medications & iodine deficiency or excess.