If the entire thyroid gland is so enlarged that you can feel it or if you clearly see swelling at the front of the throat, this is called goiter. Sometimes only part of the thyroid gland is enlarged. If there is a nodule in one location, then we refer to this as a solitary thyroid nodule. If more than one nodule is present, then the condition is called multinodular goiter. When the thyroid gland is enlarged, thyroid hormone levels can be increased, reduced or normal.

Thyroid gland enlargement may be present at birth, but it can also develop later on. A thyroid gland that is too large at birth may be caused by:

• Genetic abnormalities, which result in defective thyroid hormone synthesis (dyshormonogenesis, seen with CH, among others).
• Substances that enter the fetus via the placenta, for example antibodies from a mother with an auto-immune thyroid disorder or antithyroid medication.

Goiter that develops during childhood may be caused by:

• Thyroid gland inflammation (auto-immune: Hashimoto's thyroiditis; bacterial: acute thyroiditis; viral/post-viral: subacute thyroiditis).
• Spontaneous presentation with normal thyroid function (nontoxic goiter).
• Graves' disease..
• Too low intake of iodine (no longer occurs in Western countries), too high intake of iodine (via medication), or exceptional medicines, such as lithium or amiodarone.
• Infiltrative growth in which other tissues grow into the thyroid gland tissue (for example, histiocytosis X, lymphoma).
• Formation of a nodule or nodules (thyroid adenoma or carcinoma) or cysts.

The cause of the thyroid enlargement can be determined by means of a blood test, a radioactive iodine or technetium uptake test and an ultrasound of the throat with a needle biopsy. This cause will then determine whether treatment is needed and, if so, which treatment.