Introduction:
The thyroid gland is a small butterfly-shaped gland located in the neck. It produces two important hormones, T3 (triiodothyronine) and T4 (thyroxin), regulating different body functions like metabolism, bone growth, brain development, body temperature, and digestion. In addition, the hypothalamus-pituitary complex releases a hormone called thyroid-stimulating hormone (TSH) into the bloodstream, making the thyroid gland release T3 and T4.
Thyrotoxicosis is when the body produces an excess of thyroid hormones T3 and T4. Metabolism is the body’s pace at which it burns food to convert it into energy. There is an increased metabolism in thyrotoxicosis due to high hormone levels, causing symptoms like rapid heartbeat and weight loss.
Who Is More Affected by Thyrotoxicosis?
Thyrotoxicosis is a rare condition that affects females more commonly than males, and the risk increases with advancing age.
Is Thyrotoxicosis the Same as Hyperthyroidism?
Hyperthyroidism is a type of thyrotoxicosis. It occurs when the thyroid gland is overly active and produces high levels of thyroid hormones. In contrast, thyrotoxicosis is when there are increased levels of thyroid hormones circulating in the blood due to various conditions like intake of too many thyroid medications.
What Are the Causes of Thyrotoxicosis?
Different conditions can cause thyrotoxicosis, which includes:
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Hyperthyroidism: The thyroid gland makes and releases an excess of thyroid hormones, which is the most common cause of thyrotoxicosis.
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Grave’s Disease: Grave’s disease is the common cause of hyperthyroidism and thyrotoxicosis. It is an autoimmune condition in which the body’s immune system mistakes the thyroid cells to be invaders and tries to harm them. This increases the thyroid cells, thereby the hormones.
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Thyroiditis: Thyroiditis is inflammation of the thyroid gland, which can occur due to various causes like bacterial and fungal infections, medicines like Lithium and Interferons, post-delivery of a baby, or the immune response of the body. Thyroiditis makes the thyroid release preformed hormones into the bloodstream.
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Nodules: Nodules are small growths that develop on the thyroid gland, affecting the release of hormones. A single nodule is called a toxic nodular adenoma, whereas a multinodular goiter or Plummer’s disease has many nodules.
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Struma Ovarii: Struma ovarii is a rare cancer in the ovaries, mainly made up of thyroid tissue, causing hyperthyroidism.
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Excess Intake of Thyroid Medicines: Medicines prescribed for hypothyroidism, when taken in excess either accidentally or intentionally, can cause thyrotoxicosis in an underactive thyroid gland.
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Hamburger Thyroiditis: Consumption of beef contaminated with thyroid tissue from a cow’s neck can cause a rare form of thyrotoxicosis called hamburger thyroiditis.
What Are the Risk Factors of Thyrotoxicosis?
The various risk factors for developing thyrotoxicosis include:
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Being a female.
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Family history of thyroid disease.
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Age above 60 years.
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Post-delivery of a baby.
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Autoimmune diseases like type 1 diabetes (a chronic metabolic disorder that occurs due to less or zeroes insulin production, causing high blood sugars), pernicious anemia (a vitamin B12 deficiency that causes decreased production of red blood cells in the body), and Addison’s disease (an endocrine disorder that occurs due to insufficient production of adrenal gland hormones).
What Are the Signs and Symptoms of Thyrotoxicosis?
Symptoms vary from mild to severe, becoming more intense in severe cases.
Signs and symptoms noticed in mild and moderate cases include:
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Rapid heartbeat (tachycardia).
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Irregular heartbeat (arrhythmia).
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Unexplained weight loss.
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Muscle weakness.
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Nervousness.
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Increased irritability and anxiety.
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Increased heat sensitivity.
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Changes in the menstrual cycle.
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Feeling shaky.
Severe cases are called thyroid crisis or thyroid storm, which is very rare but can be life-threatening. Signs and symptoms noted include:
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A very rapid or fast heartbeat.
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High fever.
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Feeling confused, agitated, and sick.
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Loss of consciousness.
How Is Thyrotoxicosis Diagnosed?
Diagnosis of thyrotoxicosis is based on:
1. Physical Examination: A doctor physically checks the following:
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Thyroid gland (to know if it is enlarged or bumpy).
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Eyes (for redness and bulging).
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Heart using a stethoscope (to check for rapid and irregular heartbeat).
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Hands (to check for tremors).
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Skin (to feel if it is warm and moist).
2. Thyroid Function Testing: It is a blood test to check the levels of thyroid hormones circulating in the bloodstream. T3 and T4 are high, whereas the pituitary hormone levels are lower than average. Therefore, the blood levels of TSH are vital as it signals the thyroid gland to release T3 and T4. Thus, low levels of TSH may point to thyrotoxicosis.
3. Imaging Tests: Imaging tests are done to better understand the cause of thyrotoxicosis. The tests done to examine the thyroid gland include:
- Radioactive Iodine Uptake Test: A small amount of radioactive iodine is given by mouth to see how much of it is taken up by the thyroid. About six to 24 hours later, the gland is scanned with a gamma probe device to determine the amount of iodine taken up. If the thyroid gland takes up more iodine, it is because the gland is producing too much T4, which is common in grave diseases or thyroid nodules. If the iodine uptake is less by the gland, but the patient has thyrotoxicosis, excess T4 is getting leaked into the blood, which occurs in thyroiditis.
- Thyroid Scan: In a thyroid scan, a doctor injects a small, safe amount of radioactive liquid or radiotracer into a vein of the body and then takes several images of the thyroid gland with a special camera called a gamma camera. The radiotracer makes certain parts appear bright. A thyroid scan helps diagnose nodules, goiter, thyroiditis, or thyroid cancer.
- Thyroid Ultrasound: It is a noninvasive technique that uses high-frequency sound waves to create images of the thyroid gland. Doctors recommend thyroid ultrasound to look out for thyroid nodules.
How Is Thyrotoxicosis Managed?
Treatment of thyrotoxicosis depends on the cause. The various treatment options include:
- Radioactive Iodine: Radioactive iodine to be taken by mouth is advised in patients who have hyperthyroidism. The overactive thyroid cells get damaged by absorbing the radioactive iodine. However, the treatment shrinks the thyroid gland, leads to hypothyroidism, and needs medications to correct the hormone levels throughout their lives.
- Antithyroid Medicines: People with hyperthyroidism are advised antithyroid medicines like Methimazole (Tapazole) and Propylthiouracil (PTU) that block the thyroid gland from making hormones.
- Surgery: Surgery is advised in patients with hyperthyroidism for the removal of the thyroid gland (thyroidectomy). This causes hypothyroidism which requires medications post-surgery.
- Beta-Blockers: Beta-blockers do not decrease the thyroid hormone levels but help in controlling symptoms like increased heartbeat and tremors. Beta-blockers are advised in the treatment of thyroiditis.
- Glucocorticoids: Glucocorticoids are a type of steroids that are also prescribed to manage thyroiditis.
What Are the Complications of Thyrotoxicosis?
Untreated thyrotoxicosis can lead to complications like :
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Risk of heart diseases. As having too many thyroid hormones, brittle bones make it difficult to store calcium in the bones.
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Grave’s eye disease is a serious condition that causes bulging and redness of the eye.
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Sudden illness, surgery, or infection can trigger a rare, life-threatening condition called thyroid crisis or thyroid storm that requires immediate medical attention.
Conclusion:
Thyrotoxicosis is a rare condition in which the levels of thyroid hormones shoot up. Though it may sound dangerous, the condition is not a medical emergency. However, symptoms need to be addressed appropriately. People who experience symptoms or have risk factors have to contact health care professionals at the earliest. Doctors may advise simple blood tests to know the cause of thyrotoxicosis and start the treatment.
