Introduction:
Nontoxic goiter is a type of goiter that does not disrupt the normal functioning of the thyroid gland. The condition is prevalent in countries with iodine deficiency in their diet. Nontoxic goiters usually grow slowly without any physical signs or symptoms. They are more prevalent in females than males, and people over the age of 60 years are prone to developing the lump. The condition may or may not require any treatment, depending on the symptoms that might be present.
What Is a Goiter?
A goiter is a neck bulge or swelling caused by the enlargement of the thyroid gland. The thyroid is an endocrine gland in front of the neck. It consists of two lobes on either side of the windpipe, below the voice box. A tissue bridge known as the isthmus connects these lobes. The primary function of the thyroid is the production of thyroid hormones. The thyroid gland is normally unnoticeable, but when there is a goiter, the gland enlarges and becomes a lump that is clearly apparent. Iodine deficiency causes about 90 % of goiter cases worldwide. Goiters are mostly benign (non-cancerous) and seldom malignant (cancerous).
What Are the Types of Goiter?
Based on their functionality, goiters can be classified as:
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Toxic Goiter: Toxic goiter is a type of goiter that results from the overproduction of thyroid hormones and subsequent hyperthyroidism. It may be diffused, nodular, or multinodular.
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Nontoxic Goiter: Nontoxic goiter is defined as a goiter that does not result in the overproduction or underproduction of thyroid hormones; as a result, it is not linked to either hyperthyroidism or hypothyroidism. It may be diffused or multinodular.
What Is a Nontoxic Goiter?
Nontoxic goiters are a type of goiter that does not interfere with the normal functioning of the thyroid gland. The cause of nontoxic goiter is not usually inflammation or cancer. Nontoxic goiters are usually diffuse and localized, but they may be nodular or multinodular in some cases. Nontoxic multinodular goiters often act as a predisposing factor for developing toxic multinodular goiters.
What Are the Symptoms of Nontoxic Goiter?
Various signs and symptoms of nontoxic goiter include:
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Many patients affected by nontoxic goiters are asymptomatic, which means they do not show any physical symptoms of the disease.
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Dysphagia (difficulty swallowing due to compression of food pipe by the lump).
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Feeling of fullness in the neck.
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Hoarseness of the voice.
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Dyspnea (difficulty in breathing).
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Pain is rare and occurs only when there is bleeding in nodules.
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Swollen neck veins.
What Causes Nontoxic Goiters?
Nontoxic goiters can occur due to the following reasons:
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Physiological Goiter: Sometimes, nontoxic goiters can form during pregnancy and puberty. The thyroid gland can occasionally enlarge as a result of the pregnancy hormone known as human chorionic gonadotropin (hCG). However, this is a transient condition that gets resolved during the postpartum period.
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Iodine Deficiency: Iodine is required for the synthesis of thyroid hormones, and a diet low in iodine can cause an enlargement of the thyroid gland. However, it is not common in nations where iodized salt is a staple of the diet.
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Sporadic: In some instances, nontoxic can may develop randomly without apparent cause.
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Goitrogens: Certain drugs and substances disrupt thyroid hormone production and stimulate unusual growth of the thyroid gland. Examples: cabbage and drugs like Para-amino salicylic acids.
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Radiation Exposure: Exposure to high-dose radiation increases the risk of thyroid nodules and even thyroid cancer.
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Thyroid-Stimulating Hormone (TSH) Release: The pituitary gland reacts to low thyroid hormone levels and increases the secretion of thyroid-stimulating hormone (TSH) to stimulate the thyroid to produce more hormones. This causes the thyroid to grow, eventually producing a nontoxic or toxic goiter.
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Thyroiditis: An inflammatory thyroid disorder called thyroiditis results in thyroid swelling and pain. It causes either an increase or decrease in thyroxine production, which ultimately results in gland enlargement.
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Thyroid Nodule: The thyroid gland enlarges overall when fluid-filled lumps, commonly referred to as nodules, grow on both sides of the thyroid gland.
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Thyroid Cancer: The thyroid may enlarge broadly as a result of specific thyroid malignancies. These include papillary thyroid carcinoma and infiltrating thyroid, among others.
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Grave’s Disease: The thyroid gland swells due to increased thyroid-stimulating hormone (TSH) release.
Who Is at Risk of Developing Nontoxic Goiter?
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People who live in geographical locations like mountains and areas with excessive rain are often prone to developing goiter because the most common cause of nontoxic goiter is iodine deficiency. And iodine is absorbed from the soils; in these areas, the iodine from the soil is washed away, and there is a deficiency of iodine in their diet.
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In developing countries, people do not have a diet enriched with an adequate amount of iodine; therefore, they develop iodine deficiency and subsequently develop nontoxic goiter.
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The rate of incidence in people who are over 60 years of age is five to six percent. Therefore, people who are older are at more risk of developing goiter.
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Goiter is almost four times more common in females as compared to males.
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Low socioeconomic status is also a risk factor for nontoxic goiter.
How Common Is Nontoxic Goiter?
The average rate of incidence of goiter globally is around 15.8%. However, the rate increases and decreases in developed, developing, and underdeveloped countries sharply. In the case of mild iodine deficiency, the rate of incidence is around five percent to 20 %, and in the case of moderate deficiency, the rate of occurrence is 20 % to 30 %. In the case of severe deficiency of iodine, the rate of occurrence is 30 % approximately. In the absence of iodine deficiency, the rate of incidence of goiter is about five percent.
How Are Nontoxic Goiters Diagnosed?
Clinical examination and examination of the patient's numerous signs and symptoms are initially used to diagnose nontoxic goiter, followed by these evaluations:
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Blood Tests: Any variations in the thyroid hormone levels causing nontoxic goiter can be detected by blood tests. The levels of thyroid-stimulating hormone (TSH), free thyroxine (T4), and free triiodothyronine (T3) should be assessed to evaluate whether the patient is thyrotoxic, hypothyroid, or euthyroid.
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Ultrasound: Ultrasound examination may be done to assess the nodule and to determine the presence of increased vascularity, calcification, or the presence of solid components in the nodule.
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Biopsy: If nodules are present, a fine needle biopsy is performed to obtain fluid or tissue samples. Following that, the samples are examined for thyroid cancer.
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Thyroid Scan: An image of the thyroid is created on a computer screen by injecting a radioactive substance into the thyroid gland. A thyroid scan checks whether the thyroid gland is working properly.
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Imaging Tests: Image tests are performed to assess the goiter's size and the presence of nodules.
How Are Nontoxic Goiters Treated?
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Treatment for Asymptomatic Goiter: Nontoxic goiters evolve slowly and without any symptoms; therefore, in most cases, they do not require any treatment. However, a close check and regular follow-ups are needed to monitor the functioning and any sudden change in the nature of the goiter.
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Levothyroxine Therapy: It is also helpful in suppressing nontoxic goiter. But, thyroid hormone replacement therapy is not advised if the goiter is autonomous (functioning or toxic).
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Radioactive Iodine Treatment: Radioactive iodine is given to reduce the size of the enlarged thyroid gland.
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Surgical Treatment: This may be employed in compressive symptoms and complications like dysphagia, dyspnea, etc.
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Thyroidectomy: It is a procedure of surgical removal of the thyroid gland, is recommended and performed in case of retrosternal nontoxic goiter (goiter that grows into the thoracic cavity) even if it is asymptomatic.
Conclusion:
Nontoxic goiters are a common form of goiter that develops slowly and gradually, usually asymptomatic. The condition often does not require immediate treatment; however, the healthcare provider should regularly check the lump for a sudden change in its functioning. Nontoxic goiters rarely develop any complications.
