Thyroid function
The thyroid gland is located in the front of your neck, just below your Adam's apple. This gland produces and secretes hormones essential for regulating your metabolism, the rate at which your body uses energy. The main hormones produced by the thyroid gland are thyroxine (T4) and triiodothyronine (T3). These hormones influence almost every organ in the body and play a key role in growth, development, and body temperature regulation.
The production and release of thyroid hormones are regulated by the pituitary gland, a small gland located at the base of the brain. The pituitary gland produces thyroid-stimulating hormone (TSH), which stimulates the thyroid gland to produce and release T4 and T3. The amount of TSH produced by the pituitary depends on the levels of T4 and T3 in the blood; this process is known as negative feedback. When T4 and T3 levels are low, TSH production increases to encourage the thyroid gland to produce more hormones, and vice versa.
Thyroid problems
When the thyroid gland isn't functioning properly, it can lead to various conditions that impact your overall well-being. Here are the most common thyroid problems, each with its own unique symptoms, causes, and treatment options.
Underactive thyroid (hypothyroidism)
Hypothyroidism is a condition in which the thyroid gland doesn't produce enough thyroid hormones to meet your body's needs. This leads to a slowed metabolism, which can cause various symptoms:
- Symptoms : Fatigue, weight gain, cold intolerance, constipation, dry skin, hair loss, muscle weakness, depression, and sluggishness.
- Causes : The most common cause of hypothyroidism is Hashimoto's thyroiditis, an autoimmune disease in which the immune system attacks and damages the thyroid gland. Other causes may include iodine deficiency, radiation therapy, surgical removal of the thyroid gland, and certain medications.
- Treatment : Hypothyroidism is usually treated with synthetic thyroid hormone (levothyroxine), which must be taken daily to normalize hormone levels.
Overactive thyroid (hyperthyroidism)
Hyperthyroidism occurs when the thyroid gland produces too many hormones, leading to an accelerated metabolism. This can lead to a range of symptoms:
- Symptoms : Weight loss, fast heart rate, nervousness, anxiety, tremors, excessive sweating, insomnia, diarrhea, and bulging eyes (in Graves' disease).
- Causes : Graves' disease is the most common cause of hyperthyroidism and is an autoimmune disease that overstimulates the thyroid gland. Other causes may include thyroid nodules (toxic adenoma or multinodular goiter), thyroiditis (inflammation of the thyroid gland), and excessive iodine intake.
- Treatment : Hyperthyroidism can be treated with medications such as antithyroid drugs (which reduce thyroid hormone production), radioactive iodine (which destroys thyroid cells), or in some cases surgery to remove part of the thyroid gland.
Enlarged thyroid gland (goiter)
Goiter refers to an enlarged thyroid gland, which may be visible as a swelling in your neck. Goiter can occur in both hypothyroidism and hyperthyroidism and can have several causes:
- Symptoms : Visible swelling in the neck, difficulty swallowing or breathing, hoarseness, and in some cases a tight feeling in the neck.
- Causes : The causes of goiter can vary and include iodine deficiency (which leads to thyroid enlargement in an attempt to produce more hormones), Hashimoto's disease, Graves' disease, thyroid nodules, and cancer.
- Treatment : Treatment for goiter depends on the underlying cause and may range from observation (in mild cases) to medications, radioactive iodine, or surgery in severe cases.
Thyroiditis (Thyroiditis)
Thyroiditis refers to inflammation of the thyroid gland, which can lead to temporary hyperthyroidism followed by hypothyroidism. Symptoms can vary depending on the stage of the inflammation:
- Symptoms : Pain and tenderness in the neck, fatigue, rapid heart rate, weight loss or gain, and mood swings.
- Causes : Thyroiditis can be caused by autoimmune diseases (such as Hashimoto's disease or postpartum thyroiditis), viral infections, or as a reaction to certain medications.
- Treatment : Treatment depends on the type of thyroiditis and can range from pain relievers and anti-inflammatory medications to hormone replacement therapy for hypothyroidism.
Thyroid cancer
Thyroid cancer is a malignant tumor that originates in the thyroid cells. Although thyroid cancer is relatively rare, it is one of the most common forms of cancer in women.
- Symptoms : A lump in the neck, hoarseness, difficulty swallowing or breathing, and sometimes pain in the neck or throat.
- Causes : The exact causes of thyroid cancer are unknown, but risk factors may include radiation exposure, genetic predisposition, and certain benign thyroid disorders.
- Treatment : Treatment for thyroid cancer depends on the type and severity of the cancer and may include surgery, radioactive iodine therapy, radiation therapy, or chemotherapy. The prognosis varies, but many cases of thyroid cancer have a good outcome, especially if detected and treated early.
Thyroid values
To diagnose and treat thyroid problems, it's essential to measure thyroid hormone levels in the blood. The main values doctors assess are TSH, free T4, and sometimes free T3:
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TSH (Thyroid Stimulating Hormone)
TSH is often the first test performed to assess thyroid function. An elevated TSH level can indicate hypothyroidism (an underactive thyroid), while a decreased TSH level can indicate hyperthyroidism (an overactive thyroid). -
Free T4 (Thyroxine)
Free T4 is the main thyroid hormone circulating in the blood. Low levels of free T4 can indicate hypothyroidism, while high levels can indicate hyperthyroidism. -
Free T3 (Triiodothyronine)
Free T3 is the active thyroid hormone that is converted from T4. This hormone is sometimes measured when free T4 and TSH do not provide sufficient information about thyroid function, especially when hyperthyroidism is suspected.
In addition to these baseline values, additional tests such as anti-TPO antibodies (to identify autoimmune diseases such as Hashimoto's or Graves' disease) and imaging studies such as ultrasound or thyroid scintigraphy may be helpful in making a diagnosis and planning treatment.
