(See also Overview of Thyroid Function Overview of Thyroid Function The thyroid gland, located in the anterior neck just below the cricoid cartilage, consists of 2 lobes connected by an isthmus. Follicular cells in the gland produce the 2 main thyroid hormones... read more .)
Simple nontoxic goiter, the most common type of thyroid enlargement, is frequently noted at puberty, during pregnancy, and at menopause. The cause at these times is usually unclear. Known causes include
Intrinsic thyroid hormone production defects
Ingestion of foods that contain substances that inhibit thyroid hormone synthesis (goitrogens, eg, cassava, broccoli, cauliflower, cabbage), as may occur in countries in which iodine deficiency is common
Medications that can decrease the synthesis of thyroid hormone (eg, amiodarone or other iodine-containing compounds, lithium)
Iodine deficiency Iodine Deficiency In the body, iodine (I) is involved primarily in the synthesis of 2 thyroid hormones, thyroxine (T4) and triiodothyronine (T3). Iodine occurs in the environment and in the diet primarily as... read more is rare in North America but remains the most common cause of goiter worldwide (termed endemic goiter). Compensatory small elevations in thyroid-stimulating hormone (TSH) occur, preventing hypothyroidism Hypothyroidism Hypothyroidism is thyroid hormone deficiency. Symptoms include cold intolerance, fatigue, and weight gain. Signs may include a typical facial appearance, hoarse slow speech, and dry skin. Diagnosis... read more , but the TSH stimulation results in goiter formation. Recurrent cycles of stimulation and involution may result in nontoxic nodular goiters. However, the true etiology of most nontoxic goiters in iodine-sufficient areas is unknown.
Symptoms and Signs of Simple Nontoxic Goiter
Patients with goiter are usually asymptomatic. Those with larger goiters may present with a dysphagia, hoarseness, or a sensation of fullness in the throat (globus pharyngis) (1 Symptoms and signs reference Simple nontoxic goiter, which may be diffuse or nodular, is noncancerous hypertrophy of the thyroid gland without hyperthyroidism, hypothyroidism, or inflammation. Except in severe iodine deficiency... read more ). The patient may have a history of low iodine intake or overingestion of food goitrogens, but these phenomena are rare in North America.
In the early stages, the goiter is typically soft, symmetric, and smooth. Later, multiple nodules and cysts may develop.
Symptoms and signs reference
1. Sajisevi M, Caulley L, Eskander A, et al. Evaluating the Rising Incidence of Thyroid Cancer and Thyroid Nodule Detection Modes: A Multinational, Multi-institutional Analysis. JAMA Otolaryngol Head Neck Surg 2022;148(9):811-818. doi:10.1001/jamaoto.2022.1743
Diagnosis of Simple Nontoxic Goiter
Thyroidal radioactive iodine uptake
Thyroxine (T4), triiodothyronine (T3), and thyroid-stimulating hormone (TSH) levels
In the early stages, thyroidal radioactive iodine uptake may be normal or high with normal thyroid scans. Thyroid function test Laboratory Testing of Thyroid Function The thyroid gland, located in the anterior neck just below the cricoid cartilage, consists of 2 lobes connected by an isthmus. Follicular cells in the gland produce the 2 main thyroid hormones... read more results are usually normal. Thyroid antibodies are measured to rule out Hashimoto thyroiditis Hashimoto Thyroiditis Hashimoto thyroiditis is chronic autoimmune inflammation of the thyroid with lymphocytic infiltration. Findings include painless thyroid enlargement and symptoms of hypothyroidism. Diagnosis... read more .
In endemic goiter, serum TSH may be slightly elevated, and serum T4 may be low-normal or slightly low, but serum T3 is usually normal or slightly elevated.
Thyroid ultrasonography is done to determine whether there are nodules Approach to the Patient With a Thyroid Nodule Thyroid nodules are benign or malignant growths within the thyroid gland. They are common, increasingly so with increasing age. (See also Overview of Thyroid Function.) The reported incidence... read more that are suggestive of cancer Thyroid Cancers Thyroid cancer can derive from follicular cells or parafollicular C-cells. Most thyroid cancers manifest as asymptomatic nodules. Diagnosis is often by fine-needle aspiration biopsy but may... read more .
Treatment of Simple Nontoxic Goiter
Depends on cause
In iodine-deficient areas, eliminate iodine deficiency by these means:
Iodine supplementation of salt
Oral administration of iodized oil
Intramuscular administration of iodized oil yearly
Iodination of water, crops, or animal fodder
Any goitrogens (eg, cassava, broccoli, cauliflower, cabbage) being ingested should be stopped.
In other instances, suppression of the hypothalamic-pituitary axis with thyroid hormone blocks thyroid-stimulating hormone (TSH) production (and hence stimulation of the thyroid).
Moderate doses of levothyroxine (100 to 150 mcg orally once a day depending on the serum TSH) are useful in younger patients to reduce the serum TSH to the low-normal range. Levothyroxine is contraindicated in older patients with nontoxic nodular goiter because these goiters rarely shrink and may harbor areas of autonomy, so that levothyroxine therapy can result in hyperthyroidism Hyperthyroidism Hyperthyroidism is characterized by hypermetabolism and elevated serum levels of free thyroid hormones. Symptoms include palpitations, fatigue, weight loss, heat intolerance, anxiety, and tremor... read more .
Large goiters occasionally require surgery to shrink the gland enough to prevent interference with respiration or swallowing or to correct cosmetic problems.
Treatment with iodine-131 for large goiters is generally ineffective unless there is clear evidence of autonomous function manifested by a suppressed TSH.
Thyroid function is usually normal.
When the cause is iodine deficiency, iodine supplementation is effective treatment.
Blocking thyroid-stimulating hormone production by giving levothyroxine is useful in younger patients to halt stimulation of the thyroid and shrink the goiter.
Surgery may be needed for large goiters.
Drugs Mentioned In This Article
|Cordarone, Nexterone, Pacerone
|Eskalith, Eskalith CR, Lithobid
|Ermeza, Estre , Euthyrox, Levo-T, Levothroid, Levoxyl, Synthroid, Thyquidity, Thyro-Tabs, TIROSINT, TIROSINT-SOL, Unithroid