Hypothyroidism & Hyperthyroidism


Hyperthyroidism is a condition that occurs when the thyroid gland produces too much thyroid hormone. Your thyroid gland is located at the front of your neck. Thyroid hormones regulate your body metabolism. Metabolism refers to all of the chemical processes that take place in your body. This includes the production of energy and hormones, tissue growth, elimination of waste products, and the distribution of nutrients in the blood.

Hyperthyroidism can affect all of your body functions. It causes the body’s normal rate of functioning to speed up. This can result in physical, behavioral, and emotional changes. Untreated hyperthyroidism can lead to serious medical problems. Hyperthyroidism cannot be prevented, but it is generally treatable and rarely fatal.


Your thyroid gland is located in the front lower part of your neck, in front of your windpipe. Your thyroid produces two thyroid hormones– thyroxine (T4) and triiodothyronine (T3). The thyroid hormones are secreted into your blood circulation and travel throughout your body. They regulate the function of every cell and tissue in your body. T4 and T3 are necessary for good health and control of your metabolism and energy levels.

The hypothalamus and pituitary gland in your brain regulate T4 and T3 production. When T4 and T3 levels are low, the hypothalamus produces thyrotropin-releasing hormone (TRH) to signal the pituitary gland to produce thyroid stimulating hormone (TSH). The TSH travels in the bloodstream and signals the thyroid gland to produce more T4 and T3. When T4 and T3 levels are high, the pituitary gland stops producing TSH.


Hyperthyroidism, also called thyrotoxicosis, occurs when the thyroid gland is overactive and produces too much thyroid hormone. Grave’s Disease is the most common cause of hyperthyroidism. Thyroid nodules, abnormal growths on the thyroid gland, can also produce too much thyroid hormone. Thyroiditis causes antibodies that damage the thyroid gland and also affect thyroid hormone production. A rare cause of hyperthyroidism is from consuming food or medications that contain high levels of iodine.


The symptoms of hyperthyroidism differ from person to person. The symptoms you have may depend on how much thyroid hormone your thyroid gland is producing, how long you have had the condition, and your age. Hyperthyroidism can affect your behavior, emotions, and physical health.

Hyperthyroidism causes your metabolic rate to speed up. You may have a fast irregular heartbeat and palpitations. You may have hand tremors. It may be difficult to breathe, even when you are resting. Hyperthyroidism can cause your body temperature to rise. You may feel warm and sweat a lot. Your skin may be red and itchy. Because your body is working at a faster speed, you may feel exhausted and have muscle weakness.

Hyperthyroidism can make you feel anxious, nervous, depressed, and irritable. You may also feel restless and moody. You may have difficulty sleeping.

Your digestive system can also be affected by hyperthyroidism. Your digestive system may speed up and cause diarrhea. You may experience frequent bowel movements. You may even lose weight, even though you are eating normally.

Your hair may become fine. It may become thin and fall out. Your fingernails may become soft and easy to break.

Females may experience irregular menstrual periods that are lighter and shorter. You may even skip periods. In some women, the ovaries stop producing eggs, which can cause temporary infertility. Additionally, an undiagnosed thyroid problem in early pregnancy can cause miscarriage.

Both men and women can experience a decreased sex drive. In males this can lead to impotence. Hyperthyroidism can cause some men to stop producing sperm, causing temporary infertility. Breast enlargement is considered a classic sign of hyperthyroidism in men.

People with Grave’s Disease may have additional symptoms. These include goiter, skin and eye problems. A goiter is an enlarged thyroid gland. It is painless and may reach a noticeable size. Finger “clubbing” can occur with the fingers widened at the tips. Your fingernails may become thick and lift off of the nail bed. You may also develop lumpy red skin on your shins and the tops of your feet. Grave’s Ophthalmopathy causes bulging and reddened eyes. This condition is more likely to occur in people who smoke.


Your doctor can diagnose hyperthyroidism by reviewing your medical history and by conducting a physical examination and blood tests. It is important that you tell your doctor about your symptoms. Your doctor can determine if you have hyperthyroidism by testing your blood. The Thyroid-stimulating hormone (TSH) assay is used to determine if the thyroid gland is functioning properly. Thyroid hormone blood tests are used to measure levels of T4 and T3.

On some occasions, your doctor may order a Thyroid Ultrasound or a Thyroid Scan and Radioactive Iodine Uptake (RAIU) Test. Thyroid scans are used to detect problems with the thyroid gland. It can identify how the thyroid gland is functioning and specify areas of overactivity or underactivity. Further, it can determine if thyroid nodules or cancer are present.

Your blood will be tested for antithyroid antibodies to diagnose Grave’s Disease. If you have Grave’s Ophthalmopathy, a Computed Tomography (CT) Scan or Magnetic Resonance Imaging (MRI) Scan can be used to view your eye structures. CT scans provide a view in layers, like the slices that make up a loaf of bread. The MRI scan is very sensitive. It provides detailed images. The CT and MRI scans are painless procedures.


The purpose of treatment is to return your metabolism back to normal and to alleviate your symptoms. The treatment that you receive depends on the cause of your condition and the severity of your symptoms. People with subclinical hyperthyroidism may be treated to avoid the symptoms of hyperthyroidism.

Hyperthyroidism is usually treated with antithyroid medications, radioactive iodine, or surgical removal of the thyroid gland. Radioactive iodine treatments destroy the thyroid gland and stop the production of thyroid hormones. Thyroidectomy is a surgery used to remove part or all of the thyroid gland through an incision on the front of the neck. People that receive radioactive iodine treatments or have their thyroid gland removed need to take thyroid hormones for the rest of their lives.

Sometimes people being treated for hyperthyroidism develop hypothyroidism because of the treatments. Hypothyroidism results when your body does not produce enough thyroid hormone. You should tell you doctor if you start to gain weight, feel tired, or feel cold. Your doctor can alter your medication to return your metabolism back to normal.

If you have Grave’s Disease you should not smoke. Smoking can lead to the development of Grave’s Ophthalmopathy. If you have Grave’s Ophthalmopathy you will need to use eye drops to keep your eyes moist. You may also need to wear glasses to protect your eyes.


Hyperthyroidism is not preventable. However, it is treatable and there are steps you can take to help reduce your symptoms. You should contact your doctor if you think you may have hyperthyroidism. You may avoid the symptoms of hyperthyroidism by being diagnosed and treated early.

If you have hyperthyroidism, lifestyle changes may help reduce your symptoms. Avoiding caffeine and reducing stress may help relieve symptoms of anxiety, nervousness, poor concentration, and fast heartbeat. Quitting smoking can reduce your risk of developing Grave’s Ophthalmopathy if you have Grave’s Disease.

It is important that you attend all of your doctor appointments. It is important that you take your antithyroid medication at the same time each day. You doctor will continue to monitor your dose of medicine to make sure you receive the correct amount.

Am I at Risk

Risk factors may increase your likelihood of developing hyperthyroidism. People with all of the risk factors may never develop the condition; however, the chance of developing hyperthyroidism increases with the more risk factors you have. You should tell your doctor about your risk factors and discuss your concerns.

Risk factors for hyperthyroidism:

  • Women are more likely to develop hyperthyroidism than men.
  • A family history of thyroid problems, particularly Grave’s Disease, increases your risk.
  • If you have an autoimmune disease, such as Type 1 Diabetes or Addison’s Disease, you are at risk.
  • Smoking cigarettes is associated with an increased likelihood of developing Grave’s Disease.
  • Stress may also increase the risk for developing hyperthyroidism.


The most serious complication of hyperthyroidism is a life-threatening condition called thyroid storm or thyroid crisis. You should call the emergency medical services in your area if you experience shock and delirium. You may also experience a worsening of hyperthyroidism symptoms, such as abdominal pain, fever, and decreased mental alertness. Thyroid storm occurs when the thyroid gland releases a large amount of thyroid hormone in a short amount of time. It may occur after a serious infection or stress.

You should call your doctor immediately, go to an emergency room, or call emergency services if you have difficulty breathing, feel very tired, have a very fast heartbeat, or chest pain. These can be symptoms of a heart problem.

Other symptoms that should prompt you to call your doctor are feeling irritable, unusually high or low blood pressure, feeling nauseous, vomiting, diarrhea, fever, confusion, or drowsiness. You should call your doctor if you develop bulging reddened eyes, which are symptoms of Grave’s Ophthalmopathy. You should also call your doctor if you have trouble swallowing, if your throat is swollen, or if you are losing weight even though you are eating.


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This information is intended for educational and informational purposes only. It should not be used in place of an individual consultation or examination or replace the advice of your health care professional and should not be relied upon to determine diagnosis or course of treatment.
The iHealthSpot patient education library was written collaboratively by the iHealthSpot editorial team which includes Senior Medical Authors Dr. Mary Car-Blanchard, OTD/OTR/L and Valerie K. Clark, and the following editorial advisors: Steve Meadows, MD, Ernie F. Soto, DDS, Ronald J. Glatzer, MD, Jonathan Rosenberg, MD, Christopher M. Nolte, MD, David Applebaum, MD, Jonathan M. Tarrash, MD, and Paula Soto, RN/BSN. This content complies with the HONcode standard for trustworthy health information. The library commenced development on September 1, 2005 with the latest update/addition on April 13th, 2016. For information on iHealthSpot’s other services including medical website design, visit www.iHealthSpot.com.