Hyperthyroidism ( overactive thyroid gland )

Issue

Vol. 1 No. 1 (2024)

Date Log

Submitted
May 23, 2024
Accepted
June 29, 2024
Published
June 24, 2024

Understanding Hyperthyroidism ( Overactive Thyroid Gland ): Causes, Symptoms, and Treatment Options

https://doi.org/10.69512/ajphi.v1i01.38
Pratikshya Thapa, MD
Department of Internal Medicine, University of South Florida, Florida, USA
Shruti Kumari, MD
B.P. Koirala Institute of Health Sciences, Dharan, Nepal
Gauri Adhikari, MD
Nepalese Army Institute of Health Sciences-College of Medicine, Kathmandu, Nepal

Corresponding Author(s) : Pratikshya Thapa, MD

pari54thapa@gmail.com

The American Journal of Patient Health Info, Vol. 1 No. 1 (2024)

Abstract


  1. Hyperthyroidism occurs when you have an excess amount of thyroid hormone produced by your thyroid gland.

  2. The common symptoms of hyperthyroidism include rapid heartbeat, weight loss, sweating, tremors, anxiety, irritability, fatigue, and heat intolerance.

  3. The most common cause of hyperthyroidism is Graves’ disease. It is an autoimmune condition where the body produces antibodies that stimulate the thyroid. 

  4. Thyroid-stimulating immunoglobulins (TSI) are highly specific for Graves' disease and are not commonly found in other thyroid conditions, such as Hashimoto's thyroiditis or thyroid cancer.

  5. Treatment of hyperthyroidism includes antithyroid medications to decrease hormone production, radioactive iodine to destroy thyroid cells, or surgery to remove part or all of the thyroid gland.

Keywords

Antithyroid Medication Radioactive Iodine Graves’ Disease Hyperthyroidism
Thapa, MD, P., Kumari, MD, S., & Adhikari, MD, G. (2024). Understanding Hyperthyroidism ( Overactive Thyroid Gland ): Causes, Symptoms, and Treatment Options. The American Journal of Patient Health Info, 1(1). https://doi.org/10.69512/ajphi.v1i01.38
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References
  1. De Leo S, Lee SY, Braverman LE. Hyperthyroidism. The Lancet. 2019 Aug;388(10047):906–18. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5014602/
  2. Antonelli A, Ferrari SM, Ragusa F, Elia G, Paparo SR, Ruffilli I, et al. Graves’ disease: Epidemiology, genetic and environmental risk factors and viruses. Best Pract Res Clin Endocrinol Metab 2020;34(1):101387.
  3. Torpy JM, Lynm C, Golub RM. Hyperthyroidism. JAMA. 2011 Jul 20;306(3).
  4. Schneider SA, Tschaidse L, Reisch N. Thyroid Disorders and Movement Disorders—A Systematic Review. Mov Disord Clin Pract 2023;10(3):360–8.
  5. Himal Bikram Bhattarai, Ishwor Thapaliya, Shrawan Dhungana, Prabesh Bikram Singh, Bhattarai M, Bidushi Pokhrel, et al. Unilateral proptosis in a patient with thyroid eye disease: A case report. SAGE Open Medical Case Reports. 2023 Jan 1;11(10.1177/2050313X231190669). Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10392154/
  6. Sarkar D. Recurrent pregnancy loss in patients with thyroid dysfunction. Indian journal of endocrinology and metabolism. 2012;16(Suppl 2):S350-1. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3603072/
  7. Liu X, Wang Y, Ma L, Wang D, Peng Z, Mao Z. High prevalence of erectile dysfunction in men with hyperthyroidism: a meta-analysis. BMC Endocr Disord 2024;24(1):58.
  8. La Vignera S, Vita R. Thyroid dysfunction and semen quality. Int J Immunopathol Pharmacol 2018;32:205873841877524.
  9. Navarro P, Rocher S, Miró-Martínez P, Oltra-Crespo S. Radioactive iodine and female fertility. Sci Rep 2022;12(1):3704
  10. Iqbal A, Rehman A. Thyroid Uptake and Scan. PubMed. Treasure Island (FL): StatPearls Publishing; 2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK555978/
  11. Carballo M, Quiros RM. To Treat or Not to Treat: The Role of Adjuvant Radioiodine Therapy in Thyroid Cancer Patients. Journal of Oncology. 2012;2012(10.1155/2012/707156):1–11. Available from: https://www.hindawi.com/journals/jo/2012/707156/.
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Pratikshya Thapaa, Shruti Kumarib, Gauri Adhikaric

a Department of Internal Medicine, University of South Florida, Florida, USA

b B.P. Koirala Institute of Health Sciences, Dharan, Nepal

c Nepalese Army Institute of Health Sciences-College of Medicine, Kathmandu, Nepal

Background

Thyroid gland is a small butterfly-shaped gland located at the base of the neck in front of your windpipe and food pipe. The thyroid gland produces thyroid hormone. Hyperthyroidism occurs when your thyroid gland becomes hyperactive and produces excess hormones. Women are more likely than men to have hyperthyroidism, affecting younger people more than older ones.1

Graves disease (GD) is the most common cause of hyperthyroidism in developed countries. It is more commonly seen between people of 30 and 60 years, with 5-10 times increased frequency in women. About 79% of the people are genetically predisposed, and about 21% of them have some environmental factors as a risk factor.2

Risk Factors of Hyperthyroidism

Figure 1.

  • Graves' Disease: This is known as the most common cause of hyperthyroidism. It is an autoimmune disorder where the body produces antibodies called thyroid-stimulating immunoglobul-ins (TSI) that stimulate the thyroid gland to produce excess hormones, leading to hyperthyroidism symptoms.3
  • Thyroid Nodules: Sometimes, nodules or lumps form in the thyroid gland, which can autonomously produce thyroid hormones, leading to hyperthyroidism. These nodules can be noncancerous (toxic adenomas) or cancerous.
  • Thyroiditis: Inflammation of the thyroid gland can release stored thyroid hormones into the bloodstream, resulting in a temporary surge of thyroid hormones in the blood, leading to hyperthyroidism. This inflammation can be due to viral infections, autoimmune conditions, or seen during or after pregnancy, called postpartum thyroiditis.
  • Tumors of the Pituitary Gland or Thyroid: Tumors in the pituitary gland can cause excessive production of Thyroid Stimulating Hormone (TSH), which stimulates the thyroid gland to produce thyroid hormones. Additionally, tumors in the thyroid gland itself can lead to excess thyroid hormone production.
  • Iodine-Containing Medications: Certain medications, such as amiodarone (used to treat heart rhythm problems), can contain high levels of iodine, contributing to hyperthyroidism in susceptible individuals.
  • Pregnancy: Hyperthyroidism can develop during pregnancy due to changes in hormone levels and immune function. This condition is known as gestational transient thyrotoxicosis and typically resolves after childbirth.
  • Subacute Thyroiditis: This condition involves thyr-oid gland inflammation, often following a viral infection, and can cause temporary hyperthyroidism followed by hypothyroidism as the thyroid gland becomes less active.

Symptoms of Hyperthyroidism

The symptoms of hyperthyroidism include:

Figure 2.

  • Rapid Heartbeat (Tachycardia): The heart may beat faster than normal, leading to palpitations, chest pain, or sometimes irregular heartbeat (arrhythmia).
  • Heat Intolerance: People with hyperthyroidism may feel excessively warm or sweat more than usual, even in cooler temperatures.
  • Increased Metabolism: Hyperthyroidism speeds up the body's metabolism, causing nervousness, restless-ness, difficulty concentrating, and insomnia.
  • Tremors: You may notice tremors in your hand or fingers. The tremors that occur in hyperthyroidism are due to the overactivity of the nervous system. 4
  • Weight loss: Individuals with hyperthyroidism often experience significant weight loss despite maintaining or even increasing their food intake. The high levels of thyroid hormone boost the metabolism rate, causing the body to burn calories more quickly.
  • Fatigue: Despite increased energy levels, individuals with hyperthyroidism may experience fatigue and weakness, often due to the strain on the body.
  • Muscle Weakness: Hyperthyroidism can lead to muscle weakness, particularly in the upper arms and thighs.
  • Changes in Menstrual Patterns: Women with hyperthyroidism may experience lighter menstrual periods and less frequent or irregular cycles. This irregularity is due to the hormonal imbalances caused by thyroid dysfunction.
  • Bulging of Eyes: The bulging of the eyes is also known as exophthalmos. It is commonly seen in Grave’s disease due to the swelling of the tissues and muscles behind the eyes. Most commonly, people have bilateral proptosis, while some may also develop unilateral proptosis.5
  • Thinning of the Skin and Hair: Skin may become thin and fragile, making it prone to bruising and other injuries. Similarly, your hair may become brittle and more prone to breakage, leading to hair loss.

Infertility and Hyperthyroidism

Hyperthyroidism can potentially impact fertility in both men and women. However, the extent of its effects can vary depending on factors such as the severity of the condition and how well it is managed. Here's how hyperthyroidism can affect fertility:

Figure 3.

  • Menstrual Irregularities: In women, hyperthyroidism can disrupt menstrual cycles, leading to irregular periods or even the absence of menstruation (amenorrhea). This can make it more difficult to conceive, as irregular ovulation can reduce the chances of successful fertilization.
  • Ovulatory Dysfunction: Hyperthyroidism can interfere with the normal functioning of the ovaries, leading to ovulatory dysfunction. When ovulation is disrupted, it becomes harder for women to conceive.
  • Increased Risk of Miscarriage: Some studies suggest that untreated or poorly controlled hyperthyroidism may increase the risk of miscarriage. Thyroid hormone imbalances can interfere with the implantation and growth of the embryo. It can affect the proper development and functioning of the placenta, ultimately leading to miscarriage.6
  • Decreased Libido and Erectile Dysfunction: In men, hyperthyroidism can lead to reduced libido (sex drive) and erectile dysfunction, which can affect fertility by decreasing the ability to achieve conception through sexual intercourse.7
  • Sperm Abnormalities: Hyperthyroidism may also affect sperm production and quality in men, potentially leading to reduced fertility. Research suggests that thyroid hormone imbalances can impair sperm production, motility, and morphology (shape).8
  • Hormonal Imbalances: Thyroid hormones play a crucial role in regulating other hormone systems in the body, including the reproductive hormones. Imbalances in thyroid hormones can disrupt the delicate hormonal environment necessary for conception and pregnancy.
  • Treatment Effects: Some treatments for hyperthyroidism, such as antithyroid medications or radioactive iodine therapy, can have temporary or permanent effects on fertility. It's essential for individuals with hyperthyroidism who are planning to conceive to discuss the potential impacts of treatment with their healthcare provider.9

Diagnosis of Hyperthyroidism

The diagnoses of hyperthyroidism include the following:

Figure 4.

  • Blood Tests: Measurement of the levels of thyroid hormones and TSH can tell us about the activity of the thyroid gland. In hyperthyroidism, levels of thyroid hormones (triiodothyronine, T3, thyroxine, T4) are typically elevated, while TSH levels are suppressed or low. These blood tests help confirm the diagnosis and determine the severity of the condition.
  • Thyroid Stimulating Immunoglobulin (TSI) Test: In cases of suspected Graves’ disease, a blood test for thyroid-stimulating immunoglobulins (TSI) is performed. Elevated levels of TSI indicate the presence of antibodies that confirm the diagnosis of Graves’ disease.
  • Thyroid Imaging: Imaging tests such as thyroid ultrasound can help your doctor evaluate the thyroid gland's size and structure.  These tests can also help identify nodules, inflammation, or other thyroid gland abnormalities that may contribute to hyperthyroidism.
  • Radioactive Iodine Uptake Test: This test involves administering a small dose of radioactive iodine orally or intravenously. Following the administration,  the amount of radioactive iodine taken up by the thyroid gland is measured. Increased radioactive iodine uptake is characteristic of hyperthyroidism and can help differentiate it from other thyroid disorders.10
  • Additional Tests: Depending on the individual's symptoms and medical history, additional tests such as a thyroid fine-needle aspiration biopsy (FNAB) or other specialized imaging studies may be recommended to evaluate thyroid nodules or other abnormalities further.

Treatment of Hyperthyroidism

The treatment of hyperthyroidism helps to normalize the levels of thyroid hormone, reduce the symptoms, and address the cause. Treatment options may be different depending on various factors like cause, severity, the individual's age, overall health, and personal preferences. The primary treatment modalities are:

Figure 5.

  • Antithyroid Medications: These medications inhibit thyroid hormone production. The most commonly used antithyroid drugs include methimazole (Tapazole) and propylthiouracil (PTU). These medications are often prescribed as initial treatment, especially for individuals with Graves' disease or toxic nodular goiter. They may be used as a long-term treatment or to prepare for other therapies such as radioactive iodine or surgery.
  • Beta-Blockers: Beta-blockers such as propranolol or atenolol are prescribed to manage symptoms such as rapid heartbeat (tachycardia), tremors, and anxiety while waiting for the effects of antithyroid medications or other treatments to take effect. Beta-blockers do not directly affect thyroid hormone levels but can provide symptomatic relief.They also prevent the peripheral conversion of T4 to T3 ( T3 is an active form of thyroid hormone)
  • Radioactive Iodine Therapy (RAI): RAI therapy involves ingesting a small, carefully measured dose of radioactive iodine. The radioiodine is selectively taken up by the overactive thyroid cells. The radiation then destroys these cells, leading to a reduction in thyroid hormone production. This therapy is often used as a definitive treatment for hyperthyroidism, particularly in cases of Graves' disease or toxic nodular goiter. It may result in hypothyroidism over time, necessitating lifelong thyroid hormone replacement therapy.11
  • Thyroidectomy (Surgery): Thyroidectomy involves surgical removal of part (subtotal thyroidectomy) or all (total thyroidectomy) of the thyroid gland. This option is reserved for individuals who cannot tolerate antithyroid medications, are not good candidates for RAI therapy, or have large goiters causing compression symptoms. Surgery provides a rapid resolution of hyperthyroidism but carries risks such as damage to the parathyroid glands and recurrent laryngeal nerves, as well as the requirement of thyroid hormone replacement therapy for lifelong.

Questions To Ask Your Doctor

  1. Is hyperthyroidism curable?
  2. Are there any contraindications for radioactive iodine?
  3. How often do I need to monitor my thyroid function?
  4. What should I do about my hyperthyroidism if I want to get pregnant?
  5. What changes can I make in my diet?

References

  1. De Leo S, Lee SY, Braverman LE. Hyperthyroidism. The Lancet. 2019 Aug;388(10047):906–18. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5014602/
  2. Antonelli A, Ferrari SM, Ragusa F, Elia G, Paparo SR, Ruffilli I, et al. Graves’ disease: Epidemiology, genetic and environmental risk factors and viruses. Best Pract Res Clin Endocrinol Metab 2020;34(1):101387. Available from: https://pubmed.ncbi.nlm.nih.gov/32107168/
  3. Torpy JM, Lynm C, Golub RM. Hyperthyroidism. JAMA. 2011 Jul 20;306(3). Available from: https://jamanetwork.com/journals/jama/fullarticle/1104118
  4. Schneider SA, Tschaidse L, Reisch N. Thyroid Disorders and Movement Disorders—A Systematic Review. Mov Disord Clin Pract 2023;10(3):360–8. Available from: https://pubmed.ncbi.nlm.nih.gov/36949803/
  5. Himal Bikram Bhattarai, Ishwor Thapaliya, Shrawan Dhungana, Prabesh Bikram Singh, Bhattarai M, Bidushi Pokhrel, et al. Unilateral proptosis in a patient with thyroid eye disease: A case report. SAGE Open Medical Case Reports. 2023 Jan 1;11(10.1177/2050313X231190669). Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10392154/
  6. Sarkar D. Recurrent pregnancy loss in patients with thyroid dysfunction. Indian journal of endocrinology and metabolism. 2012;16(Suppl 2):S350-1. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3603072/
  7. Liu X, Wang Y, Ma L, Wang D, Peng Z, Mao Z. High prevalence of erectile dysfunction in men with hyperthyroidism: a meta-analysis. BMC Endocr Disord 2024;24(1):58. Available from: https://pubmed.ncbi.nlm.nih.gov/38689308/
  8. La Vignera S, Vita R. Thyroid dysfunction and semen quality. Int J Immunopathol Pharmacol 2018;32:205873841877524. Available from: https://pubmed.ncbi.nlm.nih.gov/29737216/
  9. Navarro P, Rocher S, Miró-Martínez P, Oltra-Crespo S. Radioactive iodine and female fertility. Sci Rep 2022;12(1):3704. Available from: https://pubmed.ncbi.nlm.nih.gov/35260614/
  10. Iqbal A, Rehman A. Thyroid Uptake and Scan. PubMed. Treasure Island (FL): StatPearls Publishing; 2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK555978/
  11. Carballo M, Quiros RM. To Treat or Not to Treat: The Role of Adjuvant Radioiodine Therapy in Thyroid Cancer Patients. Journal of Oncology. 2012;2012(10.1155/2012/707156):1–11. Available from: https://www.hindawi.com/journals/jo/2012/707156/.

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