Why do we develop Goitre?

Enlargement of the thyroid gland is called Goitre. The thyroid gland is situated in the front of the neck on or just below the thyroid cartilage (Adam’s apple). The thyroid gland is made up of lobules, each of which has 20-40 follicles. The follicles are lined by epithelial cells and contain in their centre, colloid (Thyroglobulin).

The thyroid gland produces two thyroid hormones, T4 which is converted to the active T3. These are mostly bound to carrier proteins that transport them to every corner of the body. These proteins maintain an constant blood level of free hormones for use by the cells of the body. The hypothalamus senses the amount of thyroxine in circulation and adjust the dose of TRH (Thyrotropin releasing hormone) secreted. TRH stimulates the anterior pituitary gland to produce TSH (Thyroid stimulating hormone) which sits on the receptor on the thyroid cells and stimulate the production of T4 and T3 from Thyroglobulin in the colloid centres of the follicles. These hormones by a negative feed back mechanism inhibit the TRH production. In this way, the levels of thyroid hormones are closely controlled by the Pituitary gland (the master gland of the body).

Thyroid hormones play a very important role of contolling the body’s metabolism and energy generation. It stimulates the breakdown of carbohydrates and fats and increases protein synthesis in all the cells of the body. Thyroxine plays a critical role in the development of a baby’s brain.

The thyroid gland is controlled and maintained by the TSH hormone. If for any reason, the production of T4 is affected, the increased TSH released, stimulates the growth of the thyroid gland in order to increase hormone production resulting in the development of a goitre.

Initially under the influence of TSH, the follicles start to grow (hyperplastic phase)where the goitre is diffusely and symmetrically enlarged (with a smooth surface) and later on they start involuting and get filled up with colloid. With continued stimulation by TSH, certain follicles enlarge excessively (due to relative increased sensitivity to TSH) to produce a large irregular (bumpy) gland called a multinodular goitre. The rapid growth of the follicles can lead to rupture,scarring, calcification and haemorrhage (with a sudden increase in size).

Goitres of this size are pretty common in a doctors practice!
A large multinodular goitre!
Common causes for Goitre

Large goitres apart from looking unsightly, may press on neighbouring structures in the neck to produce a variety of symptoms. Often a spontaneous bleed into the goitre can lead to a sudden increase in size and provoke discomfort in a hitherto asymptomatic person. I myself developed a thyroid lump overnight after being elbowed by my son, about 10 yrs ago when I was playfully wrestling with him. This was aspirated (bloody fluid was removed with a syringe) with complete resolution of the swelling. Compression of the esophagus could cause diffculty in swallowing. I had a patient recently who had a mass pressing the esophagus from the side. After extensive evaluation it was confirmed that it was of thyroidal origin and she was recommended surgery. Her neck was completely normal looking without any swelling whatsoever. But the goitre had grown downwards into the chest.

Compression of the wind pipe (trachea) could cause difficulty in breathing and stridor (noisy breathing). Thyroidal swellings could also cause hoarseness of voice due to compression of the nerve supplying the vocal cords (usually due to a malignant thyroid). The superior vena cava (the largest vein in the neck) could be compressed causing Superior Vena Caval syndrome with symptoms of congestion of the face, distension of the veins of the neck and a “bursting” headache on bending down! Large goitres could also harbour cancer.

How do you know if the neck swelling that you have is a Goitre? All thyroid masses move upwards on swallowing as the thyroid gland is enveloped by the deep fascia of the neck and is connected to which the thyroid cartilage of the larynx which moves upwards during swallowing.

An overactive thyroid may present with the following symptoms: increased appetite, increased sweating, heat intolerence, diarrhoea, palpitations, weight loss, reduced menstrual flow.

An underactive thyroid may present with reduced appetite, weight gain, cold intolerence, constipation, slowed heart rate and mental activity, increased body weight and increased menstrual blood loss.

Ofcourse, you may have no symptoms if your thyroid levels are normal (Euthyroid state).

What are the indications for surgery for someone with a thyroid mass?

The following are indications for surgery:

1.Large goitre with pressure symptoms.

2.Cosmetic reasons and if patient wishes for surgery.

3.Hyperthyroidism due to toxic adenoma.

4.When an FNAC is done and if cancer is suspected or proven – surgery is indicated if the patient is elderly, male, with a hard thyroid mass which is fixed to the neck structures, with a hoarse voice or with enlarged lymph nodes in the neck.

So if you have a thyroid swelling, see your doctor who may arrange some tests and the have a discussion with him/ her as to what you must do further.