Hyperthyroidism (Overactive Thyroid)

What is Hyperthyroidism (Overactive Thyroid)?

The thyroid gland is a small butterfly shaped gland that is located in the lower front of the neck just under the Adam's apple. The thyroid gland produces hormones that control the body's organ functions and metabolism.

Hyperthyroidism is an overfunctioning of the thyroid gland which results in the production of excessive thyroid hormones. This speeds up most of the chemical reactions in the body and causes mental and physical changes. An excess of thyroid hormones causes a toxic condition called thyrotoxicosis.

Approximately 2 % of American adults suffer from hyperthyroidism. It is more prevalent in women than in men, by a ratio of about 8 to 1 and is most common in young to middle-aged women. Overactive thyroid gland is potentially dangerous thyroid condition and, if left untreated, can cause potentially fatal heart rhythm abnormalities and osteoporosis.

Hyperthyroidism causes

Hyperthyroidism is usually caused by an autoimmune condition. An autoimmune disease occurs when the body's immune system becomes misdirected and attacks the very organs, cells, or tissues that it was designed to protect.

For some reason the body suddenly recognizes the thyroid gland as foreign, and starts to attack it. The reason for this is unclear. However, instead of destroying the gland this attack actually stimulates it. The thyroid gland starts to overwork and produce excess thyroid hormone.

Hyperthyroidism can be caused by:

  • Graves' disease, named after Robert Graves, the physician who first described this form of hyperthyroidism. Graves' disease (known as Basedow disease) is the most common cause of hyperthyroidism, accounting for 60 to 80 percent of all cases. It is an autoimmune disease caused by an antibody, active against the thyroid-stimulating hormone (TSH) receptor, which stimulates the gland to synthesize and secrete excess thyroid hormone. Graves disease occurs more frequently in women than in men, at a ratio of 8:1 female to male.
  • Toxic nodules or goiters on the thyroid. Toxic multinodular goiter causes 5% of the cases of hyperthyroidism in the United States and can be 10 times more common in iodine-deficient areas. It typically occurs in patients older than 40 years with a long-standing goiter, and has a more insidious onset than Graves' disease.
  • Excessive thyroid medication (treatment induced hyperthyroidism)
    • Iodine-induced [1] hyperthyroidism can occur after intake of excess iodine in the diet, exposure to radiographic contrast media, or medications. Excess iodine increases the synthesis and release of thyroid hormone in iodine-deficient patients and in older patients with preexisting multinodular goiters.
    • Amiodarone-induced [2] hyperthyroidism can be found in up to 12% of patients, especially those in iodine-deficient areas. Amiodarone, an antiarrhythmic drug, contains 37% iodine and is the most common source of iodine excess in the United States. Medications such as interferon and interleukin-2 (aldesleukin) also can cause hyperthyroidism.
    • Thyroid hormone-induced is caused by the intentional or accidental ingestion of excess amounts of thyroid hormone. Some patients may take thyroid preparations to achieve weight loss.
  • Thyroiditis (an inflammation of the thyroid)
    • Subacute thyroiditis (also known as "granulomatous” thyroiditis) produces an abrupt onset of thyrotoxic symptoms as hormone leaks from an inflamed gland. It often follows a viral illness. Symptoms usually resolve within eight months. This condition can be recurrent in some patients.
    • Lymphocytic thyroiditis (Hashimoto's disease) and postpartum (subacute lymphocytic) thyroiditis are transient inflammatory causes of hyperthyroidism that, in the acute stage, may be clinically indistinguishable from Graves' disease. Postpartum thyroiditis can occur in up to 5 to 10% of women in the first three to six months after delivery. A transient hypothyroidism often occurs before resolution.

Hyperthyroidism risk factors

  • Pregnancy - 5 to 8% of women develop postpartum inflammation of the thyroid
  • Age 20 to 50 years
  • Women are more likely than men to develop hyperthyroidism
  • Family history of Graves' disease or other forms of hyperthyroidism increases your risk
  • Japanese ancestry appear to be at greater risk of hyperthyroidism
  • Previous treated/untreated problems (nodules, hyperthyroidism, goiter, hypothyroidism)
  • Another autoimmune disease

Hyperthyroidism symptoms

All the symptoms can be caused by other problems, and so the diagnosis may not be obvious at first. Usually the symptoms of hyperthyroidism are so gradual in their onset that people don't realize the symptoms until they become more severe. This means the symptoms may continue for weeks or months before people fully realize that they are sick. In older people, some or all of the typical symptoms of hyperthyroidism may be absent, and the person may just lose weight or become depressed.

The symptoms usually are related to an increase in the metabolic rate of the body. Common symptoms include:

  • Enlarged thyroid gland
  • Rapid heart beat (tachycardia) or heart palpitations
  • Warm, moist skin
  • Increased sweating
  • Heat intolerance
  • Trouble sleeping
  • Nervousness, irritability
  • Restlessness
  • Anxiety
  • Depression
  • Fatigue
  • Tremor of the fingertips
  • Skin changes (smooth, velvety skin)
  • Weight loss
  • Fine brittle hair
  • Increased appetite
  • Increased bowel movements, diarrhea
  • Changes in sex drive
  • Muscle weakness, especially in the upper arms and thighs
  • For women, irregular menstrual cycle and reduced menstrual flow

Treatment of overactive thyroid

The main aim of treatment is to reduce the level of thyroxine to normal.

Anti-Thyroid Drugs

For patients with sustained forms of hyperthyroidism, such as Graves' disease or toxic nodular goiter, antithyroid medications are often used. These drugs act directly on the thyroid gland to block the production of thyroid hormones. Two common drugs in this category are methimazole and propylthiouracil (PTU). When taken rightly, they are usually very effective in controlling hyperthyroidism within a few weeks. The main shortcoming is that the underlying hyperthyroidism often comes back after they are discontinued especially in patients over the age of 45 years, also in those with a large goitre and in those with severe hyperthyroidism. For this reason, many patients with hyperthyroidism are advised to consider a treatment that permanently prevents the thyroid gland from producing too much thyroid hormone.

Radioactive Iodine

Radioactive iodine (RAI) is the most widely recommended permanent treatment of hyperthyroidism. This treatment has been used since 1940, and no serious complications from RAI have become apparent to the date. Radioactive iodine takes advantage of the fact that thyroid cells are the only cells in the body which have the ability to absorb iodine. When thyroid cells absorb radioactive iodine they will be damaged or killed. Because iodine is not concentrated by any other cells in the body, there is very little radiation exposure for the rest of the body. This form of therapy often takes one to two months before the thyroid has been killed, but the radioactivity medicine is completely gone from the body within a few days.

The main problem is, that because the damage to the thyroid cannot be controlled, the thyroid of most patients becomes underactive (hypothyroidism) after RAI. This condition is then treated with a thyroid hormone supplement. This may seem silly - trading one thyroid problem for another. But hyperthyroidism much more dangerous, and difficult to control, than is hypothyroidism. So while becoming hypothyroid may not be a perfect outcome, it is much better than being hyperthyroid.

Surgical Removal of the Gland or Nodule

Another permanent cure for hyperthyroidism is to surgically remove all or part of the thyroid gland. This surgery is known as a thyroidectomy. Surgery is not used as frequently as the other options. The biggest reason for this is that the most common forms of hyperthyroidism are a result of overproduction from the entire gland and the methods described above work quite well in the vast majority of cases. A potential downside of the surgical approach is that there is a small risk of injury to structures near the thyroid gland in the neck. The incidence of this is about 1%. Like radioactive iodine treatment, surgery often results in hypothyroidism. Therefore, anyone who has been hyperthyroid and been treated by one of the above methods should have a blood test at least once a year to measure thyroid function.

Supplements helpful for Hyperthyroidism

Natural treatments can often reduce or eliminate the need for drugs and surgery. Since metabolism is dramatically increased in this condition, nutrients are used up more quickly than normal. For this reason, multivitamins provide the necessary replacements. In addition, add vitamins C and B complex for extra support from the stress of such overactivity. The essential fatty acids often help treat autoimmune reactions. They provide building blocks for prostaglandins, which prevent inflammation in the body. Other important nutrients for thyroid health are zinc, copper, selenium, iodine, grape seed extract, coenzyme Q10 and the amino acid, tyrosine.

  • Calcium
    Reduced bone mass has been identified as a common problem in cases of hyperthyroidism. Research indicates that early detection of the problem and treatment with a calcium supplement helps to reduce the risk of osteoporosis.
  • Melatonin
    Supplementation with melatonin is beneficial for insomnia, which is a common symptom of hyperthyroidism. Melatonin is a substance secreted by the pineal gland in the brain. It plays a role in sleep patterns and the circadian rhythms of the body. Melatonin has been shown to suppress thyroxine production. It is also a potent antioxidant and an effective free radical scavenger in hyperthyroidism.
  • L-carnitine
    L -carnitine is a periferal antagonist of thyroid hormone action at in some tissues [3]. Nutritional supplementation with L-carnitine has been shown to have a beneficial effect on the symptoms of hyperthyroidism, and it may help prevent bone demineralization caused by the disease. Carnitine is an amino acid that plays a pivotal role in the production of energy inside the cell. Carnitine also had beneficial effects on bone metabolism.
  • Niacin
    Niacin (Vitamin B3, nicotinic acid) was shown in a clinical trial to decrease the concentration of serum thyroid hormones in individuals who were euthyroid [4]. Because no adverse effects of supplementation were observed, niacin may be an adjunctive therapy for hyperthyroidism. It may be wise to use niacinamide, another form of niacin, because it does not cause flushing.
  • Vitamin A
    Vitamin A and beta-carotene levels in the blood of patients with hyperthyroidism are often decreased and supplementing with large amounts of this particular vitamin actually inhibits thyroid function. The supplementation of Vitamin A also ameliorates the symptoms of Grave's disease. Vitamin A is a potent antioxidant, which thwarts the oxidative stress that is increased in those with hyperthyroidism.
  • Vitamin C
    Vitamin C is a potent anti-oxidant. It has been shown in experimental studies to be decreased in individuals with excess thyroid hormone activity.
  • Vitamin E
    Vitamin E is an anti-oxidant. It also functions to stabilize cell membranes. It can act as a free radical quencher and decrease the damage caused by oxidative stressors in hyperthyroid patients.
  • Digestive enzymes
    Digestive enzymes may be beneficial in cases of overactive thyroid. The ability of the body to adequately digest and absorb nutrients from the diet may be reduced in people with hyperthyroidism.

Herbal remedies helpful for overactive thyroid

Lycopus ssp, Lithospermum officinale, and Melissa officinalis have all been proven to treat hyperthyroidism. The mechanism of action in these herbs, is the blocking of TSH receptors on the thyroid cells. These three herbs have had repeated success in treating Grave's disease as well, because of interruption of the Grave's specific thyroid stimulating immunoglobulin. In fact, one study found that freeze dried extracts of the three herbs inhibited binding of TSH to thyroid receptors by weakly binding themselves.

Herbs and supplements to avoid

According to animal study, the herb ashwagandha may raise thyroid hormone levels[5]. For this reason, it should not be used by people with overactive thyroid. Taking excessive kelp, bladderwrack, or other forms of seaweed can cause hyperthyroidism by overloading the body with iodine.


  • 1. Bürgi H. Iodine excess. Best Pract Res Clin Endocrinol Metab. 2010 Feb;24(1):107-15. PubMed
  • 2. Basaria S, Cooper DS. Amiodarone and the thyroid. Am J Med. 2005 Jul;118(7):706-14. PubMed
  • 3. Benvenga S, Ruggeri RM, Russo A, Lapa D, Campenni A, Trimarchi F. Usefulness of L-carnitine, a naturally occurring peripheral antagonist of thyroid hormone action, in iatrogenic hyperthyroidism: a randomized, double-blind, placebo-controlled clinical trial. J Clin Endocrinol Metab. 2001 Aug;86(8):3579-94. PubMed
  • 4. Shakir KM, Kroll S, Aprill BS, Drake AJ 3rd, Eisold JF. Nicotinic acid decreases serum thyroid hormone levels while maintaining a euthyroid state. Mayo Clin Proc. 1995 Jun;70(6):556-8. PubMed
  • 5. van der Hooft CS, Hoekstra A, Winter A, de Smet PA, Stricker BH. Thyrotoxicosis following the use of ashwagandha. Ned Tijdschr Geneeskd. 2005 Nov 19;149(47):2637-8. PubMed

Created: August 18, 2006
Last updated: February 24, 2016

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