If you notice a swelling in your neck or have trouble swallowing or breathing, it's important to consult a doctor who can determine if you have a goitre and recommend the best treatment as per your needs. Dr Sunil Chumber, Head of the Department of Surgical Discipline, AIIMS Delhi, and his team members share insight into disease causes and their management with ARCHANA JYOTI

The thyroid gland, shaped like a butterfly and located in the neck, can enlarge, causing a condition known as goitre. There are two main types: diffuse, where the gland enlarges uniformly, and multinodular (MNG), characterized by lumpy growths due to nodules.

MNG develops gradually over the years, potentially growing large enough to compress the food pipe and windpipe, leading to symptoms discussed in this article.

Worldwide, goitre affects 500-600 million people, more prevalent in regions with insufficient dietary iodine. However, the actual number is estimated to be about 167 million. MNG is said to be endemic when it affects more than 10 per cent of a given population. The Government of India in 2021 reports the prevalence of self-reported goitre to be at 2.9 per cent which increased from 2.1 per cent reported in 2016. The incidence in non-endemic regions is 0.1 per cent to 1.5 per cent. Non-endemic goitre is more common in women and the elderly. Overall it is three times more common in females than in males in both endemic and non-endemic regions. In areas where goitres are common (endemic areas), nodules can form early in life, while in other places they appear later although many people may not even know they have a goitre until therein in his or her late 40s and 50s. In India, the main endemic goitre belt is a sub-Himalayan region and other pockets of endemic goitre are present in many states.

Causes and Risk Factors

Understanding the cause of your thyroid enlargement helps in planning further treatment with your doctor. The thyroid is essential for regulating your body’s metabolism. It does this via the production and secretion of thyroid hormone (thyroxine).  When a goiter develops, it indicates that the gland is enlarged which happens due to issues with its functions.

Here are some reasons why MNG can happen:

Lodine deficiency

Iodine is required for the production of thyroid hormone in the thyroid gland. This production is under regulation by the hypothalamus and pituitary gland (small glands located near the brain) which produce chemicals called TRH and TSH. When there’s not enough iodine, the thyroid enlarges to produce more hormones under the influence of TRH and TSH. The stimulation is not always continuous, and all the areas do not grow at the same rate leading to nodule formation. If the deficiency remains for a long time, the thyroid can enlarge to a very big size.

Goitrogens

Certain foods like cabbage, kale, broccoli, and cassava contain substances that interfere with the production of thyroid hormones. When eaten in large amounts for a long period of time these can lead to enlargement of the thyroid as it tries to overcome the interference.

Autoimmune thyroiditis

Sometimes the body's immune cells (cells responsible for fighting outside germs) go haywire and attack the body's cells, oftentimes triggered after an infection. When thyroid cells become the target, it can lead to the accumulation of these cells inside the gland and destroy the normal gland structure.

Cancer

Although not a common cause, irregular growth of cancer cells can lead to nodule formation in the thyroid gland.

Pregnancy and growth spurt

During pregnancy and puberty, there is an increase in the demand for thyroid hormone in the body. These can cause temporary thyroid enlargement, usually associated with smooth enlargement and rarely causing nodule formation. These do not require any treatment.

Genetics

In some cases, genetic factors can affect how the thyroid works, leading to nodules.

Unknown Causes

Not all nodular goitre can be ascribed to an identifiable cause. Many times the cause of multinodular goitre remains unknown. Women, older adults, and those with family members with similar conditions have more chances of having nodular goitre.                

Symptoms and Clinical Features

Most multinodular goiters do not have symptoms and are identified on routine physical examination or incidentally on imaging. Patients with a toxic multinodular goiter may have signs and symptoms of hyperthyroidism (excessive thyroid hormone production). Some people with a nodular goiter feel or see a lump in their neck which is usually the main reason for seeking a doctor’s opinion.

At times, during a scan done for other purposes nodules can be picked up in the thyroid. Patients can experience any other associated symptoms like,

Feeling anxious or having trouble sleeping/ Feeling weak or tired/ weight loss despite good appetite/ Feeling one’s rapid heartbeat/ heat intolerance and excessive sweating/ frequent bowel movements/ nervousness and restlessness/ tremors/ Thinning of hairs/ irregular menstruation (in women)

If a nodular goitre is very large, it might cause compression on the food pipe or airway thereby causing the following symptoms:

Wheezing/ coughing/a choking feeling (food or pills getting stuck in the throat)/ Difficulty in swallowing/Difficulty in breathing (especially when lying flat)

These symptoms can happen if the goiter is huge and long standing or if it’s growing into the chest, called a substernal goiter.

(To be concluded)