Hypothyroidism Can Cause Enlargement Of The Thyroid

Every organ in our body is of paramount importance and vital for the sustenance of life. Efficient working, even of the thyroid, an organ as little as a size of pea, is so crucial that it can be a matter of life and death in extreme cases.

The Thyroid is located at the base of neck, most importantly associated with metabolism (burning of food to produce energy). Other than metabolism, thyroid hormones are also important for normal growth and development, cardiac functions, Gastro Intestinal motility and sexual functions.

Enlargement Of The Thyroid; Goiter:

The thyroid gland is a butterfly shaped organ located at the base of neck in close vicinity with trachea (windpipe) and esophagus (food pipe). The enlargement of thyroid is known as goiter, that can sometimes be seen as a bump or swelling in neck. When the thyroid works less efficiently, it grows in its size. In fact 90% of goiters occurs due to hypothyroidism (underactive thyroid).

The question arises why low level of thyroid hormones causes the enlargement of gland instead of its shrinkage? The answer to this question is very interesting and will make you admire the complex working of the body. Elaborately, our body has the tendency to keep the internal environment near normal, that is known as homeostasis. Any change that tries to disturb the natural homeostasis is dealt with.

The organ or system subjected to the challenging situation makes an attempt to face it by adapting to it. This means that if thyroid levels drop due to the incapacity of the thyroid to work properly, our body’s natural response is try to adjust the defect. In an attempt to compensate the fault in thyroid, thyroid cells start to proliferate (grow). Therefore, enlargement of thyroid is an attempt to compensate the underactivity of the thyroid to make hormones.

What Causes Goiter?

As mentioned earlier, hypothyroidism is responsible for the goiter in 90% of cases. Now that we have come to know how hypothyroidism results in enlargement of thyroid, let’s find out what can be the cause of goiters;

Iodine Deficiency:

Iodine deficiency is a cause of hypothyroidism and can ultimately cause goiters (Delange F, Thyroid, Spring, 1994). Basically, iodine is needed by the thyroid gland for the biosynthesis of its hormones. When the body is deprived of iodine and is consequently making less thyroid hormones, the pituitary gland senses it and starts releasing more and more TSH hormone. TSH stands for thyroid stimulating hormone and as the name indicates, it stimulates the thyroid gland to release hormones. But with such large amounts, TSH negatively impacts thyroid causing it to grow and goiter occurs.

Hashimoto’s Disease:

It is an autoimmune condition that is the leading cause of hypothyroidism in areas where iodine is in sufficient quantities. Hashimoto’s disease is caused by destruction of a normal thyroid gland by the immune system. The resultant damaged thyroid is not able to produce enough hormones. Then the pituitary senses the decline in thyroid hormones and stimulates the thyroid to work by releasing TSH and the thyroid enlarges as a result.

Does Only Hypothyroidism Cause Goiters?

Hypothyroidism is the main cause of goiters. Yet, hyperthyroidism can also result in goiters. Now you may be wondering what can be the cause of enlargement of the thyroid gland when it is already producing enough hormones? Adaptation doesn’t answer this question in hyperthyroidism case. It is the antibodies produced in hyperthyroidism that are the main culprit.

In Graves’ disease (hyperthyroidism), as it is an autoimmune condition, the immune system produces antibodies to destroy the gland. One of the antibodies, that also contribute in goiters, is thyroid stimulating immunoglobulin (TSI). It acts just like the normal TSH (thyroid stimulating hormone) released by pituitary gland. Basically, TSI stimulates the thyroid to grow and also causes increased secretion of hormones. The pituitary gland then senses increased synthesis of hormones and decreases its own secretion of TSH. Despite ultimate low levels of TSH, the thyroid keeps on growing larger causing hyperthyroidism under the command of TSI antibodies.

What Can Be The Consequences Of A Goiter?

Goiters don’t produce any particular symptoms of their own. Instead, a goiter is more of a sign in itself and doesn’t necessarily produce pain.

However, a goiter can pose a problem by compressing the nearby structures, because of its large size. There is difficulty swallowing food if the esophagus (food pipe) is compressed, while if the trachea (wind pipe) is under pressure, the person chokes.

Nodular goiters occur in very few cases. The enlargement of thyroid, in this case, is due to formation of nodules in the thyroid. People, most of the times, confuse nodules with cancerous growth. That is actually a misconception. 95% of thyroid nodules are benign (non-cancerous), and it is only 5% that may cause cancer. Therefore, you can conclude nodules are not more than abnormal excessive growth of cells in most people. Fortunately, it is not a problem in most cases.

What Can You Do To Avoid Goiter?

Other than giving you cosmetic issues, a goiter can impact nearby structures making it difficult for you to breath and eat. Indeed, breathing and eating are the two important functions for you to survive. Therefore, it is better to take precautionary measures to avoid the enlargement of thyroid. These steps can also be taken after you develop a goiter, as in most cases a goiter is reversible. However, for accurate treatment, consult your primary physician.

Adequate Intake Of Iodine:

Iodine deficiency is the leading cause of goiters, which is luckily preventable. Iodine is needed by your thyroid to make hormones and its shortage causes hypothyroidism. Iodine intake reverses the problem and provides your thyroid with the needed amount of iodine to make thyroid hormones. Iodine intake as a treatment, after the development of goiter, is found to cause visible changes in the thyroid causing it to shrink back.

Avoid Excessive Consumption Of Iodine:

Importance of iodine gets highlighted by the fact that iodine is necessary for the biosynthesis of thyroid hormones. Therefore, one would think the more iodine intake there is, the better the thyroid gland works. But this is not the case. Excessive iodine shuts off thyroid hormone production causing hypothyroidism. It is because the body perceives excess iodine as excess thyroid hormone production. To counterbalance this excessive hormones production, which is actually not the case, the thyroid is ordered to make less hormones. Thus, thorough a negative feedback mechanism, the thyroid slows down. Therefore, the thyroid makes less hormones directed by excessive iodine availability.

How Can You Find Out You Have Goiter?

A goiter can be seen easily, with the naked eye, as a swelling in neck. However, presence of a goiter indicates an abnormality of the thyroid gland. To diagnose the underlying pathology, blood tests can be done to distinguish hypothyroidism or hyperthyroidism as the susceptible cause.

Furthermore, to inspect autoimmune condition, additional tests are warranted. Presence of specific antibodies gives positive findings. To diagnose nodular goiter, fine needle biopsy can be done. These tests are ordered by your primary physician or endocrinologist.

Can A Goiter Be Life Threatening?

A Goiter itself typically doesn’t pose any life threats, but a large multinodular goiter can be proved fatal if it compresses the food and wind pipes and is not treated in a timely manner. Moreover, a large goiter can compress the large nerves in neck and upper thoracic region causing superior vena cava syndrome (blood flow impedance in a large vein; superior vena cava). The incidence of malignancy is low in a multinodular goiter, it is less than 5%, but not zero, so cancer is a matter of concern with the changes in size and associated symptoms (Robbins, 9th edition, pg728).

Conclusion:

A Goiter is the enlargement of the thyroid that occurs due to iodine deficiency in 90% cases. In such case, symptoms of hypothyroidism are also present. The other causes for the development of goiter are autoimmune conditions associated with the thyroid gland. They are Hashimoto’s disease causing hypothyroidism and Graves’ disease that cause hyperthyroidism.

Goiters, by themself, are typically not harmful unless it grows to a size big enough to compress the nearby structures, making it difficult to eat and breath.

References:

https://www.endocrineweb.com/conditions/thyroid/thyroid-goiter

https://www.thyroid.org/goiter/

https://www.endocrineweb.com/conditions/goiters/thyroid-goiter-basics

http://www.mayoclinic.org/diseases-conditions/goiter/manage/ptc-20264969

http://www.webmd.com/women/understanding-goiter-basics

http://www.medicalnewstoday.com/articles/167559.php

http://www.goiter.us/effects-treatment.html

https://med.uth.edu/orl/newsletter/large-benign-goiters-special-considerations-management/

http://www.healthline.com/health/multinodular-goiter#outlook8

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