Characteristics of Thyroid Diseases

Function and shape

In general terms, thyroid diseases result in changes in “function” and changes in “shape.” Some diseases cause changes in both, while others cause only one kind of the change.

Changes in thyroid function

Some diseases may cause a condition called “thyroid dysfunction,” in which abnormalities occur in the production of thyroid hormones. These may lead to excessive or insufficient levels of thyroid hormones.

[Hyperthyroidism]

This is a condition in which thyroid hormones are produced in excess. Increased levels of thyroid hormones in the blood accelerates metabolism.

[Hypothyroidism]

This is a condition in which the production of thyroid hormones is reduced, leading to a low rate of metabolism.

Changes in thyroid “shape”

Some diseases can cause swelling or lumps (nodules) in the thyroid gland, resulting in morphological changes. Swelling is called “goiter.”

[Diffuse goiter]

A condition in which the entire thyroid gland enlarges without any other morphological changes

	Simple diffuse goiter This condition occurs when the entire thyroid gland enlarges slightly without thyroid dysfunction. The condition may eventually develop into Basedow’s disease or Hashimoto’s thyroiditis.
	Basedow’s disease This is an autoimmune disease in which the presence of certain antibodies causes the thyroid gland to be overactive. Basedow’s disease causes palpitations, swelling of the thyroid gland, and symptoms associated with the eyes and vision.
	Hashimoto’s disease This disease, also called chronic thyroiditis, is characterized by chronic inflammation of the thyroid gland. Many patients exhibit no thyroid dysfunction, but some have reduced production of thyroid hormones. In certain cases, thyroid function temporarily fluctuates, a condition known as painless thyroiditis.
	Subacute thyroiditis This is a condition in which thyroid swelling is accompanied with pain. Fever is a common additional symptom. The thyroid gland temporarily releases excessive levels of hormones, causing symptoms similar to those of Basedow’s disease. However, hormone levels gradually return to normal and symptoms subside. Recurrence of subacute thyroiditis is rare.

[Nodular goiter]

A condition in which nodules are present in part of the thyroid gland

Thyroid tumor This is a condition in which nodules develop in the thyroid gland. Most patients have normal thyroid function. Some patients have fluid accumulation in sac-like nodules, forming cysts.

Each disease is explained further in the individual sections. Also, pamphlets and books providing detailed explanations and precautions for daily life are available. If you have any questions or concerns, please consult with one of our counselors.