Hormones of thyroid gland T3 and T4

Author’s Bio: Saher B. Haider has a Pharmacy degree and is a freelance writer in the health and wellness industry. In her spare time, she enjoys reading, cooking, and spending time with her family.

What is the thyroid?

The thyroid is a small, butterfly-shaped gland located at your neck’s base, slightly above your Adam’s apple. Glands are special organs that perform specific functions in your body by producing and releasing certain chemicals. The thyroid gland produces hormones that help in controlling metabolism and growth in your body. It also helps to regulate several body functions in different organs of your body. It produces two main hormones, namely T3 and T4. Together, these two hormones manage fat and carbohydrate’ metabolism in your body and control how different cells in your body use energy. They also regulate heart function, maintain normal body temperature, and play a role in protein synthesis. Lower than usual or higher levels of these hormones affect metabolism and body functions, which rely on expected levels of T3 and T4. The two most common types of thyroid disorders are hypothyroidism and hyperthyroidism. > Data from the American Thyroid Association (ATA) suggests that:    

What is hyperthyroidism?

Hyperthyroidism, also known as an overactive thyroid, is when the thyroid gland makes too much T3 or T4.

What causes hyperthyroidism?

There are several causes of hyperthyroidism in adults, with the most common one being Grave’s Disease. It is an autoimmune disorder that abnormally stimulates your thyroid gland to produce large amounts of hormones. Other causes of hyperthyroidism in adults are:  
  • Having an excess amount of iodine in the body.
  • Inflamed thyroid gland
  • Tumor of the thyroid gland or pituitary gland
  • Taking large amounts of thyroid hormone supplements and medicines, such as amiodarone and certain cough syrups

What are the symptoms of hyperthyroidism?

The excessively high amount of thyroid hormone creates an overly active metabolic state, disturbing normal body functions. People with hyperthyroidism may also develop enlarged thyroid (goiter). This is seen as a swelling on the front of the neck. The most common signs of hyperthyroidism include:
  • Increased heart rate and palpitation
  • High blood pressure
  • Hand tremors
  • Intolerance to heat, resulting in excessive sweating
  • Increased bowel movement and weight loss, both attributed to high metabolic rate
  • Increased appetite
  • Hair loss
  • Irritability and confusion
  • Difficulty in falling asleep
  • Anxiety and depression
While most of the hyperthyroid symptoms go away over the course of treatment, rapid heart rate and high blood pressure are the key symptoms that should not be ignored to prevent the risk of stroke and heart failure.

Is hyperthyroidism curable?

Hyperthyroidism is completely curable and requires timely management and regular assessment of your T3 and T4 levels.

How to treat hyperthyroidism?

Hyperthyroidism treatment will either include antithyroid medications, such as methimazole or radioactive iodine. You might also need drugs, such as beta-blockers, to lower your heart rate and control excessively high blood pressure. Our primary care providers with At Home Urgent Care are experts at tailoring an online treatment plan for hyperthyroidism. Feel free to book an online consultation session now to get your prescription/medication available online.

Antithyroid medications

These drugs interfere with the production of T3 and T4 hormones in hyperthyroidism.
It is the most commonly prescribed medication in hyperthyroidism. Methimazole is available in tablets, rectal suppositories, and enemas. However, it might not be the best treatment choice for pregnant women.

In a severely extreme case of hyperthyroidism, this medication is considered the drug of choice.

Radioactive iodine
It is recommended for use in adults with hyperthyroidism. Radioactive iodine produces specific action on the thyroid gland only and has little to no side effects on other organs.

What is hypothyroidism?

Hypothyroidism is when you have less than normal amounts of T3 and T4 hormones circulating in your blood. It is also known as the underactive thyroid gland. People with hypothyroidism do not have enough T3 and T4 hormones to regulate body functions naturally. The most common causes of hypothyroidism include inflammation of the gland (thyroiditis), Hashmito’s thyroiditis, and post-partum thyroiditis. Other reasons that may result in hypothyroidism are iodine deficiency and a poorly functioning thyroid gland from birth.

Hypothyroidism Symptoms

Since thyroid hormones majorly control all processes of your body, their deficiency slows down normal body functions. 

Common hypothyroid symptoms are:

  • Lower heart rate
  • Reduced blood pressure
  • Tiredness 
  • Intolerance to cold, making you feel colder.
  • Weight gain
  • A decrease in bowel movements resulting in constipation

How to treat hypothyroidism?

Hypothyroidism treatment helps maintain normal levels of T3 and T4 in your blood so that your normal metabolic processes and other critical body functions are restored. Common treatment options include thyroid replacement therapy, which includes synthetic T4 and/or T3 treatment.

Levothyroxine is a synthetic hormone that maintains normal levels of T3 and T4 and reverses the symptoms of hypothyroidism,

Treating hypo and hyperthyroidism requires strict monitoring of thyroid hormone levels and symptoms and dose adjustment. People on hyperthyroidism treatment are at risk of developing hypothyroidism and vice versa.


Where is the thyroid located? The thyroid gland is located on the front of your neck, just above your Adam’s apple.

What does your thyroid do? 
It makes thyroid hormones triiodothyronine (T3) and tetraiodothyronine (T4). The hormones have a vital role in regulating metabolism and other body functions.

Is hypothyroidism an autoimmune disease?
The most common cause of hypothyroidism is an autoimmune disease, also known as an antithyroid autoimmune disease (ATD) – Hashmito thyroiditis. It is a common autoimmune disease that causes hypothyroidism. Genetics also plays a strong role in thyroid diseases.

Online Doctor Consultation For Thyroid Concerns

If you or someone in your family have concerns or suffer from thyroid issues, please contact and seek help from our doctors online. At Home Urgent Care provides telehealth services so you can safely and confidently keep your health in check with our primary and urgent care services and get treatment online. Book an online doctor appointment today with our health care experts available at your convenience 365 days a year and get your prescription/medication available online.

Book an Appointment

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Step 1

Call or Book your online Doctor Visit

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Step 2

Talk to a doctor over the Phone/ Tablet

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Step 3

If needed pick up your medication at the pharmacy


  1. American Thyroid Association. “General Information/Press Room.” January 14, 2021.
  2. National Institute of Diabetes and Digestive and Kidney Diseases. “Hyperthyroidism (Overactive Thyroid).” August 2016. January 14, 2021.
  3. American Thyroid Association. “Hypothyroidism (Underactive).” January 14, 2021.