Difference Between Thyroid and Goiter

The thyroid is a gland of the endocrine system that is found in a persons’ neck. The goiter is a pathological swelling of the thyroid that can occur because of some disease or process.

What is Thyroid?

Definition:

The thyroid is one of the endocrine glands and it is located in the anterior part of the neck. This gland secretes two important hormones known as T₃ and T₄.

Structure:

The gland is divided into two parts called lobes which are joined by tissue called the isthmus. The gland also has the shape like that of a butterfly and it consists of structures known as follicles, which are enclosed by epithelial cells. The follicles all have a substance inside known as the colloid which is where hormones are made. Iodine molecules are used to form the T₃ and T₄ hormones.

Function:

Hormones that are made in the colloid are created from iodine and tyrosine using peroxidase enzymes. The hormones that are secreted are T₃ (triiodothyronine) and T₄ (thyroxine). These are important in controlling metabolism in the body.

Control:

The secretion of thyroid hormones from the thyroid is regulated via a negative feedback loop that involves both the hypothalamus and the anterior pituitary gland. Low levels of the two hormones T₃ and T₄ in the bloodstream acts as a trigger for the hypothalamus to produce thyrotropin-releasing hormone. This hormone then triggers the secretion of thyroid-stimulating hormone, also known as TSH, from the anterior pituitary gland. The TSH moves to the thyroid where it causes the gland to make the two thyroid hormones. When these hormones are at high levels, the hypothalamus causes the pituitary to stop sending TSH.

What is Goiter?

Definition:

A goiter is an unusual increase in the size of the thyroid gland due to either a lack of iodine in the diet or a disease condition such as Hashimoto’s thyroiditis.

Structure:

A goiter is comprised of one or many nodules which contain tissue that is somewhat different histologically when compared with normal thyroid gland tissue. The epithelia surrounding the follicles contain various projections and the follicles vary in size.  The epithelial layer may also be unusually thickened compared with normal epithelia. The actual goiter may or may not be visible as a swelling in the neck.

Function:

A goiter is the thyroid gland which has become larger, and thus the function may or may not be impacted. In some cases, the thyroid hormones are still produced at the same concentrations as before but in other cases too little or too much may be secreted. It is rare for the nodules to cause too little of the hormones to be produced, more commonly they cause an elevation in thyroid hormone production (hyperthyroidism).

Control:

When it comes to controlling a goiter, the aim is to reduce the size of the enlargement. This may need to be done by surgical means or in some cases, radioactive iodine can be given and can prove effective in reducing the size of the goiter.

Difference between Thyroid and Goiter?

Definition

The thyroid is an endocrine gland that is located in the neck and it produces various thyroid hormones. The goiter is a swelling that develops in the thyroid gland because of some pathological condition or a lack of iodine.

Anatomy

The thyroid gland consists of structures known as follicles that are enclosed by a layer of epithelial cells. The goiter consists of follicles of variable size which are surrounded by a thick epithelial layer that has projections present.

Lobes or nodules

There is a maximum of two lobules making up a thyroid. There are anywhere from one (uninodular) to several (multinodular) nodes making up a goiter.

Size

The thyroid gland has a maximum size of about 20 g, while a goiter can have a maximum size of up to 1000 g.

Pathological condition

A thyroid is normal tissue of the body which is not due to any pathological process. A goiter is an abnormal tissue that results from pathological processes or a lack of iodine in the diet.

Control

The thyroid gland is controlled by hormones produces by the hypothalamus and the pituitary gland. The size of a goiter can be controlled by surgery or radioactive iodine.

Table comparing Thyroid and Goiter

Summary of Thyroid Vs. Goiter

• The thyroid is an endocrine gland that is found in the neck region.
• A goiter is an unusual swelling of the thyroid due to some disease process or a deficiency of iodine in the diet.
• The activity of the thyroid gland is naturally controlled by hormones produced by the hypothalamus and the pituitary gland.
• The size of a goiter can be controlled by various medical interventions such as surgery or by using radioactive iodine.

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