struma nodule thryroid

Classification

They are classified in different ways:

• A "diffuse goiter" is a goiter that has spread through all of the thyroid (and can be a "simple goitre", or a "multinodular goitre").
• "Toxic goiter" refers to goiter with hyperthyroidism. These most commonly due to Graves' disease, but can be caused by inflammation or a multinodular goiter.
• "Nontoxic goiter" (associated with normal or low thyroid levels) refers to all other types (such as that caused by lithium or certain other autoimmune diseases).

Other type of classification:

• I - palpation struma - in normal posture of head it cannot be seen. Only found when palpating.
• II - struma is palpative and can be easily seen.
• III - struma is very big and is retrosternal. Pressure and compression marks.

Causes

Worldwide, the most common cause for goiter is iodine deficiency. In countries that use iodized salt, Hashimoto's thyroiditis becomes the most common cause.

Other causes are:

• Hashimoto's thyroiditis
• Graves' disease
• Inborn errors of thyroid hormone synthesis, causing congenital hypothyroidism
• Thyroiditis (acute, chronic)
• Ingestion of goitrogens, such as casava.
• Side-effects of pharmacological therapy
• Thyroid cancer

Occurrence

Iodine is necessary for the synthesis of the thyroid hormones thyroxine (T₄) and triiodothyronine (T₃). In endemic goitre, iodine deficiency leaves the thyroid gland unable to produce its hormones because the hormones are made out of iodine. When levels of thyroid hormones fall, thyrotropin-releasing hormone (TRH) is produced by the hypothalamus. TRH then prompts the pituitary gland to make thyrotropin or thyroid stimulating hormone (TSH), which stimulates the thyroid gland’s production of T₄ and T₃. It also causes the thyroid gland to grow in size by increasing cell division.

Nodular goitre of a young woman.

Goiter is more common among women, but this includes the many types of goitre caused by autoimmune problems, and not only those caused by simple lack of iodine.

Treatment

Treatment may not be necessary if the goitre is small. Goiter may be related to hyper- and hypothyroidism (especially Graves' disease) and may be reversed by treatment of hyper- and hypothyroidism. Graves' disease can be corrected with antithyroid drugs (such as propylthiouracil and methimazole), thyroidectomy (surgical removal of the thyroid gland), and iodine-131 (¹³¹I - a radioactive isotope of iodine that is absorbed by the thyroid gland and destroys it). Hypothyroidism may raise the risk of goitre because it usually increases the production of TRH and TSH. Levothyroxine, used to treat hypothyroidism, can also be used in euthyroid patients for the treatment of goitre. Levothyroxine suppressive therapy decreases the production of TRH and TSH and may reduce goitre, thyroid nodules, and thyroid cancer. Blood tests are needed to ensure that TSH is still in range and the patient has not become subclinically hyperthyroid. If TSH levels are not carefully monitored, it is alleged that levothyroxine may increase the risk of osteoporosis but no peer reviewed studies on levothyroxine replacement of Hypothyroid patients causing this effect have actually been produced.

Thyroidectomy with ¹³¹I may be necessary in euthyroid goitrous patients who do not respond to levothyroxine treatment, especially if the patients have difficulty breathing or swallowing. ¹³¹I, with or without the pre-injection of synthetic TSH, can relieve obstruction and reduce the size of the goitre by thirty to sixty-five percent. Depending on how large the goiter is and how much of the thyroid gland must be removed or destroyed, thyroidectomy or ¹³¹ may produce hypothyroidism requiring life-long treatment.

Symptoms

The symptoms of goiter are mainly the swelling of the front part of the neck and protruding eyes.