What is goiter? – Goiter refers to a thyroid gland that grows larger than its original size. The growth may involve the whole gland or a part of it.

What is a thyroid gland?

A thyroid gland is a small, butterfly-shaped organ located in the front part of the neck, just below the Adam’s apple. It is an endocrine (hormone-producing) gland that produces thyroid hormones (triiodothyronine and thyroxine). It acts like the thermostat of the body, regulating the body temperature, digestion, metabolism, mood and heart rate.

What is the effect of goiter on thyroid hormone?

There is no specific pattern of thyroid hormone level associated with goiter, as the thyroid hormone level may be higher or lower than normal or even remain normal. 

What are the causes of goiter?

Goiter commonly develops when the cells of the thyroid react to low production of thyroid hormone. The following are common causes of goiter:

1. Iodine deficiency – This is the most common cause of goiter. Iodine is an important raw material the thyroid gland uses to produce thyroid hormone. When there is low level of iodine in the body, the cells of the thyroid gland increase in number (leading to its enlargement) in order to meet up with the production of the quantity of thyroid hormone needed by the body.
2. Pregnancy – The pregnancy hormone (human chorionic gonadotropin (hCG)) has a structure that resembles the hormone that stimulates the thyroid gland to function (thyroid stimulating hormone (TSH)). Therefore, it sometimes acts on the receptors of TSH to stimulate the thyroid gland to grow bigger.
3. Autoimmune diseases – These are conditions in which a person’s immune system (built to defend the body) starts attacking the person’s body / organs. Examples of autoimmune diseases that affect the thyroid gland, causing its enlargement, include: Grave’s disease and Hashimoto’s disease.
4. Thyroiditis – This refers to inflammation of the thyroid gland. This inflammation results in temporary enlargement of the organ.
5. Thyroid cancer – Just like cancer in any other organ, cancer of thyroid origin causes enlargement of the organ.
6. Sporadic goiter – In this case, there is no specific cause. It may sometimes be drug-induced.

What are the symptoms of goiter?

1. Goiter can be diagnosed with the following symptoms: Symptoms directly relating to the size of the thyroid gland:

1. A swelling in front of the neck just below the Adam’s apple.
2. Swelling of the neck veins.
3. Pressure or tightness in the throat.
4. Hoarseness: strained voice.
5. Wheezing: due to compression of the airway.
6. Difficulty in swallowing: due to compression of the oesophagus.

2. Symptoms relating to the functions of the thyroid gland: Excessive functioning of the gland (hyperthyroidism):

1. Bulging eyes (exophthalmos)
2. Fast heart beats (tachycardia)
3. Feeling of someone’s heart beats (palpitation)
4. Unexplained weight loss
5. Excessive sweating without exercise or change in room temperature
6. Involuntary shaking of the body
7. Diarrhoea
8. Agitation

3. Under-functioning of the thyroid gland (hypothyroidism):

1. Excessive tiredness (fatigue)
2. Sluggishness and dullness
3. Dry skin
4. Unexplained weight gain
5. Constipation
6. Abnormal menstrual flow pattern

How is goiter treated?

1. Expectant management / watchful waiting – This requires just observation while expecting the goiter to resolve on its own, without any form of treatment. This may be adopted for cases of simple goiter, with normal thyroid gland hormone levels. The thyroid hormone level is monitored from time to time in order to note any change in its activities and act accordingly.
2. Medical treatment – This requires either replacement of thyroid hormone with a medication that mimics its activities in cases of hypothyroidism (e.g. levothyroxine) or suppression of the activities of the thyroid gland in cases of hyperthyroidism (e.g. methimazole, propylthiouracil, aspirin, steroid).
3. Radioactive iodine treatment – This involves taking radioactive iodine orally. The thyroid cells take up the iodine with the aim of utilizing it to produce thyroxine. The iodine becomes toxic to the cells and kills them in the process. The gland shrinks as the treatment progresses. After this treatment, the person will most likely depend on iodine replacement medication for life.
4. Surgery – This involves the removal of the entire thyroid gland or a part of it. This may be needed to relieve the pressure of the gland on the airway or oesophagus or if the gland is cancerous. There may be need for thyroid hormone replacement treatment after surgery, especially if the whole gland is removed.

How can goiter be prevented?

The commonest type of goiter, caused by iodine deficiency, can be prevented by iodine supplementation of food products such as iodized table salt. Iodine supplementation is not required for other types of goiters as it may worsen the condition.