[Biology Class Notes] on Goiter Pdf for EXAM

In Biology, we study about the human body, its organs, and functions of the different organs. Now, it is widespread knowledge that all the organs in our system work to keep our body in its best form. The human body also has essential vitamins, proteins, minerals, etc. All these components help the body to function efficiently.  Sometimes, our body may face a deficiency in one or more of these components.  This deficiency may lead to certain conditions.  Goitre disease is due to a lack of iodine, and other reasons. In this article, we will know Goiter’s meaning and how it affects the human body.

What is A Goiter?

The definition of Goiter states that it is an enlargement of the thyroid gland on the front and sides of the neck. It is the result of abnormal thyroid secretion, especially hypothyroidism due to a lack of iodine in the diet.

Let’s discuss thyroid in brief for you to understand the topic better. The thyroid is a butterfly-shaped endocrine gland (secreting hormones directly into the blood) in your neck. It makes and secretes two hormones directly into the blood- thyroxine (T4) and triiodothyronine (T3). These hormones are essential for all cells in the body to function normally.   

Hyperthyroidism is a condition of overproduction of hormones, and hypothyroidism is a condition of the underproduction of hormones. Goiter is due to hypothyroidism or hyperthyroidism. The word Goiter indicates an enlarged thyroid and does not mean any malfunction in the thyroid gland. It is a condition that causes the thyroid to grow unevenly. Ref Fig.1  

The Causes of Goiter 

As mentioned earlier, Iodine deficiency in the body can lead to goiter. It is the leading cause of goiter. The reason is that Iodine is essential to help our thyroid gland produce thyroid hormones. When you don’t have enough Iodine in your body, the thyroid has to work extra hard to produce the hormones. This extra hard work causes the thyroid gland to grow larger, leading to goiter. The other causes of goiter include the following:

1 – Inflammation – Some people develop thyroiditis which is an inflammation of the thyroid gland. It can cause an enlargement of the gland. E.g. viral thyroiditis

2 – Graves’ Disease – This disease is due to hyperthyroidism. The overproduction of hormones leads to an expansion of the thyroid gland.

3 – Hashimoto’s Disease – Due to this thyroiditis, the thyroid gland is not able to produce enough thyroid hormone, causing hypothyroidism.  It causes the pituitary gland to make more thyroid-stimulating hormone causing the thyroid to enlarge.

4 – Nodules – Nodules are solid or fluid containing cysts that may appear on the thyroid and cause it to swell. These nodules are often non-cancerous.

5 – Thyroid Cancer – Cancer may affect the thyroid. It may cause swelling on one side of the gland. It is not very common as the nodules.

6 – Pregnancy can also sometimes cause the thyroid gland to grow in size.

Symptoms of Goiter 

The primary symptom of goiter includes swelling in the neck just below Adam’s apple. (Ref Fig.2 below). Apart from this prominently visible sign, the other symptoms are:

1 – A feeling of tightness in the throat region.

2 – Hoarseness or scratchy voice.

3 – Swelling of neck vein.

4 – Dizziness when arms are raised over the head.  

Other less common symptoms include difficulty in breathing, coughing, wheezing (due to squeezing of the windpipe), and pain in swallowing (due to squeezing of the food pipe).

Some people have goiter due to hypothyroidism. The symptoms include tiredness, dry skin, constipation, menstrual irregularities, and weight gain.

Some people may have goiter due to hyperthyroidism. In this case, the symptoms include rapid heartbeat, increase in pulse rate, nausea, vomiting, diarrhea, shaking, agitation, and sweating ta room temperature without any exercise.

Types of Goiter 

As you are aware that Goiter has many causes. The type of goiter also depends upon the cause. The different types of goiter (based upon its origin) include:

1 – Colloid Goiter (endemic) – it develops due to a lack of iodine. Iodine is a mineral essential for the  production of thyroid hormones. It is common in people living in iodine-deficient areas.

2 – Non-Toxic Goiter (sporadic) – it is unknown but may be caused due to intake of lithium by way of medications to treat mood disorders.

3 – Toxic (nodular or multinodular) Goiter – this type of goiter forms one or more small nodules that produce their own hormones. It causes hyperthyroidism.