The thyroid is a small butterfly-shaped gland inside the neck, located in front of the trachea (windpipe) and below the larynx (voice box). It uses small amounts of iodine to produce two thyroid hormones - triiodothyronine (T3) and thyroxine (T4) - that travel though the blood to all tissues of the body.
Thyroid hormones control many aspects of health, including:
The body’s "metabolic rate"
body weight and temperature
heart rate and blood pressure
growth in children
Another gland, called the pituitary gland, actually controls how well the thyroid works. The pituitary gland is located at the base of the brain and produces thyroid-stimulating hormone (TSH). The bloodstream carries TSH to the thyroid gland, where it tells the thyroid to produce more thyroid hormones, as needed.
The thyroid gland can become either overactive (hyperthyroidism) or underactive (hypothyroid) or develop nodules within it.
Other thyroid problems include cancer, thyroiditis (swelling of the thyroid gland), or a goiter, which is an enlargement of the thyroid gland.
Hyperthyroidism - Causes, Signs and Symptoms
Too much thyroid hormone from an overactive thyroid gland is called hyperthyroidism, because it speeds up the body's metabolism. One of the most common forms of hyperthyroidism is known as Graves' disease, after Robert Graves who first described it. This autoimmune disorder tends to run in families, although the exact nature of the genetic abnormality is unknown.
Because the thyroid gland is producing too much hormone in hyperthyroidism, the body develops an increased metabolic state, with many body systems developing abnormal function.
Hyperthyroidism more commonly affects women between the ages of 20 and 40, but men can also develop this condition. The symptoms of this thyroid condition can be frightening and include:
Fine tremor of the hands
Diarrhea or frequent bowel movements
Irritability and anxiety
Vision problems (irritated eyes or difficulty seeing)
Intolerance to heat and increased sweating
What are Causes of Hyperthyroid?
is the most common cause of hyperthyroidism. It occurs when the immune system produces antibodies that attack the thyroid gland, making it produce too much thyroid hormone and creating a hormone imbalance. This condition happens often in people with a family history of thyroid disease. In some patients with Graves' disease, one of the noticeable symptoms may be swelling behind the eyes, causing discomfort or increased tears or causing the eyes to push forward or bulge.
Other causes of hyperthyroidism include the following:
Thyroid nodules. (Read more on THYROID NODULES)
Taking too much thyroid hormone medication to treat other conditions.
Subacute thyroiditis. This painful inflammation of the thyroid is usually caused by a virus. When the infection leaves, the condition improves.
Lymphocytic thyroiditis and postpartum thyroiditis. These related autoimmune disorders cause a temporary painless inflammation of the gland. Thyroiditis is marked by lymphocytes (white blood cells) inside the thyroid and leads to leakage of thyroid hormone from the inflamed gland, raising hormone levels in the bloodstream.
Antithyroid Drugs: These drugs work to decrease the amount of hormone the thyroid gland makes. For most patients, the preferred drug is methimazole (MMI) because of its safety record. Propylthiouracil (PTU) may be preferred for patients who are allergic to or intolerant of methimazole (MMI) and for pregnant women in their first trimester of pregnancy.
Antithyroid drugs usually have to be taken for an extended period of one to two years or longer. In approximately 50-60% of patients with Graves’ disease the thyroid condition may go away after a course of treatment, but there could be a relapse, even years later.
Beta-blockers: Beta-blocker drugs, such as propranolol, do not block the production of thyroid hormone. Instead, they control many troubling symptoms of this hormone imbalance, especially rapid heart rate, trembling, anxiety, and the high amount of heat the body produces with this condition.
Radioactive iodine: The thyroid gland normally collects iodine out of the bloodstream to make thyroid hormone. Radioactive iodine treatment involves taking a radioactive form of iodine that causes the permanent destruction of the thyroid. The response to treatment can take from 6 to 18 weeks. Because the radioiodine often destroys some of the normal function of the thyroid gland, people who have this therapy often need to take thyroid hormone for the rest of their lives to replace their hormone levels. Most physicians agree that the desirable goal of radioactive therapy is to completely remove thyroid gland function since then there is a very low chance of hyperthyroidism coming back.
Surgery: Removal of the thyroid gland (thyroidectomy) is another permanent solution but is often the least preferred option. This procedure must be performed by a highly skilled and experienced thyroid surgeon because of the risk of damage to nerves around the larynx (voice box) and to the nearby parathyroid glands, which control calcium metabolism in the body. Surgery is recommended when there is a large goiter (enlarged thyroid gland) that makes breathing difficult or when antithyroid drugs are not working, or when there are reasons not to take radioactive iodine. It may also be used in patients who also have thyroid nodules, especially when the nodules may be cancerous. In the latter instance, additional thyroid cancer treatment is often required.
After both radioactive iodine and surgery treatments, the patient will need to be monitored regularly for adequate thyroid hormone levels in the blood. After such treatment, most patients become hypothyroid and no longer produce enough thyroid hormone. For this reason, they must take a daily supplement of synthetic thyroid hormone to correct the hormone imbalance.
If left untreated, hyperthyroidism can lead to other health problems including congestive heart failure, irregular heart rhythm which predisposes to strokes as well as osteoporosis, which causes brittle bones.
Too little thyroid hormone from an under-active thyroid gland is called hypothyroidism. In hypothyroidism, the body's metabolism is slowed. Several causes for this condition exist, most of which affect the thyroid gland directly, impairing its ability to make enough hormone. More rarely, there may be deficiency of the pituitary TSH, sometimes as a result of a pituitary gland tumor, which blocks the pituitary from producing TSH. As a consequence, the thyroid fails to produce a sufficient supply of hormones needed for good health. Whether the problem is caused by the thyroid conditions or the pituitary gland, the result is that the thyroid is underproducing hormones, causing many physical and mental processes to become sluggish.
Hypothyroidism can be a dangerous condition if untreated.
Symptoms include the following:
Dry skin and hair and hair loss
The most severe expression of hypothyroidism may be referred to as myxedema. If you have severe hypothyroidism, a significant injury, infection, or exposure to cold or certain medications may trigger a life-threatening condition called myxedema coma. This condition may cause a patient to lose consciousness and to develop hypothermia, a life-threatening low body temperature.
What are causes of hypothyroid?
is the most common cause of hypothyroidism in the United States. It occurs when the immune system produces antibodies that attack the thyroid gland, creating chronic inflammation that damages the gland and interferes with its ability to make enough thyroid hormone. It occurs more often in women than men and tends to run in families.
Hypothyroidism can be caused by several other conditions, including:
Subacute, lymphocytic, or postpartum thyroiditis. These inflammations of the thyroid gland often start as hyperthyroidism, as stored thyroid hormone leaks out of the gland and raises hormone levels in the blood. Most people then develop temporary or, very rarely, permanent hypothyroidism.
Drugs that affect thyroid function, such as amiodarone, which is used to treat heart rhythm abnormalities.
A pituitary gland that does not make enough thyroid-stimulating hormone (TSH).
Treatment for hyperthyroidism (too much thyroid hormone) with radioactive iodine or surgery.
Routine testing of babies at birth identifies any with congenital hypothyroidism, a condition in which the thyroid gland has not developed properly. This testing is essential for all newborns, because if hypothyroidism in not treated, a child could experience mental slowness or retardation, or fail to grow normally. Hypothyroidism during pregnancy can also negatively affect the baby, although if you are adequately treated and under regular supervision by an experienced endocrinologist there is no adverse effect on the baby’s development.
Hypothyroidism is increasingly common as we age. Women over 50 should consider being screened for thyroid deficiency every few years. Hypothyroidism affects as many as 15 percent of women over 70 years of age.
Hypothyroidism is treated by replacing the thyroid hormone the body needs. This is usually done with an oral tablet or pill of the thyroid hormone thyroxine (T4 or levothyroxine). A person will usually notice an improvement in his or her health and decreased symptoms of thyroid disease within two weeks. Severe cases of hypothyroidism, however, may take longer to correct and there is often a lag period between restoration of normal blood levels and full recovery from all the symptoms. Most patients with hypothyroidism will need to be on T4 treatment for the rest of their lives. They have to work closely with their doctor, take their medication as directed, and be monitored regularly in case the medication dose needs to be adjusted. If patients take too much T4, they can develop a mild case of hyperthyroidism. If they do not get enough, the symptoms of hypothyroidism will return.
A patient may need special attention if in addition to suffering from thyroid problems, he or she is:
Older or has a weak heart. Thyroid hormone can make the heart work harder. A lower dose may be needed.
Pregnant. Higher doses are usually needed during pregnancy. Frequent monitoring is required during this time, too, because the thyroid hormone dosage may change. An adjustment in dosage may be necessary after delivering the baby as well.
Having surgery. A person should have enough T4 in his or her system before surgery to undergo the anesthesia and have a satisfactory recovery. If an individual is unable to take medicine by mouth, T4 can be given intravenously after surgery.
There is controversy regarding the effects of liothyronine (T3) either on its own or as an adjunct to T4 therapy in the treatment of hypothyroidism. While large scale studies have shown no statistical benefit with the use of T3, there are undoubtedly some patients who do gain symptomatic benefit from the addition of T3, perhaps due to a failure of their own body to efficiently convert the T4 to the biologically more active T3. Taking T3 is more inconvenient as it is a twice daily regime, but as long as patients are carefully monitored to ensure the total amount of thyroid hormone is not excessive, it can be offered as a trial to patients who feel their symptoms are not fully alleviated by T4 alone.
Armour Thyroid and Nature's Thyroid
These are is a desiccated extracts of pig thyroid containing both T4 and T3. However, the relative amount of each is uncertain and variable and can lead to marked fluctuations in the blood thyroid hormone levels. Most patients who believe they would be better treated with the use of Armour should try a supervised combination of pure T4 and T3 instead, the doses of which can be more accurately monitored and adjusted. Speak with Dr. Schneider about this.
Thyroid Nodules and Thyroid Cancer
A thyroid nodule is a small swelling or lump in the thyroid gland. Thyroid nodules are common. These nodules represent either a growth of thyroid tissue or a fluid-filled cyst, which forms a lump in the thyroid gland. Almost half of the population will have tiny thyroid nodules at some point in their lives but, typically, these are not noticeable until they become large and affect normal thyroid size. About 5 percent of people develop significant sized nodules, greater than a centimeter across.
Although most nodules are not cancerous, people who have them should seek medical attention to rule out cancer. Also, some thyroid nodules may produce too much thyroid hormone or become too large, interfering with an individual's breathing or swallowing or causing neck discomfort.
Symptoms and Diagnosis of Thyroid Nodules:
More than 90 percent of thyroid nodules are not harmful or cancerous. An individual may not be aware of the nodule's presence until it starts to grow, resulting in an enlarged thyroid. A doctor may feel it, however, when he or she carefully examines the thyroid gland.
Nodules should be checked by a doctor. Tests can usually tell if a nodule is harmless or harmful and which treatment would be best. A nodule may be cancerous if the lymph nodes under the jaw are swollen and if it grows quickly, feels hard, and causes pain. Cancerous nodules may also cause hoarseness or difficulty with swallowing or breathing, although this is only the case with a small proportion of thyroid cancers.
If a patient has had radiation treatment around the head or neck areas, he or she should tell his or her doctor because this can increase an individual's chances of having nodules and cancer.
Among people who have thyroid nodules, thyroid cancer is found in about 8 percent of men and 4 percent of women. To determine whether a nodule may be harmful and whether the patient should undergo thyroid cancer treatment, the doctor may perform any number of tests. These include the following:
Ultrasound. A machine is used to show sound waves that map out a picture of the thyroid gland and any nodules contained within it.
Fine-needle aspiration (FNA) biopsy. In this test, a thin needle is inserted into the nodule to remove cells and/or fluid samples from the nodule for examination under a microscope. Dr. Schneider has vast experience in both thyroid/neck ultrasound and biopsy and performs these procedures in the office, so you get the results right away.
Thyroid scan. This is a radiation detector that scans over the neck, after a tiny amount of radioactive substance is administered, to reveal whether the nodule is functioning (producing hormones).
Blood and other laboratory tests. Tests include those that measure levels of thyroid-stimulating hormone, as well as antibodies and possibly calcitonin.
Treatment of Thyroid Nodules
Again, only about 5 percent of thyroid nodules are cancerous. If you have thyroid cancer, please remember that most patients recover well with proper thyroid cancer treatment. Thyroid cancers need to be removed by surgery, after which radioactive iodine therapy may be needed to destroy any remaining thyroid cells.
Other types of nodules, even if they are not cancerous, may also need to be removed. Most specialists recommend a total rather than partial removal of the thyroid gland. The thyroid gland and the nodules within it are removed by surgery (thyroidectomy) with use of thyroid hormone replacement treatment afterward.
Following surgery and subsequent radioactive iodine therapy, patients with thyroid cancer require monitoring for many years. The monitoring varies among patients but typically includes tests for thyroid function and serum thyroglobulin levels (a tumor marker), as well as possibly radiologic studies to include ultrasounds, CT scans, MRI scans and radioactive scans. The tests will vary based on the type of tumor.
Some nodules when scanned will show that they are collecting greater than normal amounts of radioactive iodine. These nodules are over functioning nodules, are referred to as "hot" on a scan and are usually not cancerous. They can, however, produce extra amounts of thyroid hormones and cause hyperthyroidism. Such over functioning nodules may be surgically removed or more usually treated with radioactive iodine.
If a nodule has fluid in it, it is called a cyst. To treat it, Dr. Schneider will probably drain it or monitor it for change. If these nodules return, then they may need to be removed. Nodules that have only fluid are usually non-cancerous, but nodules that have some fluid and some solid matter can be cancerous and need to undergo thyroid cancer treatment.
Surgery on the thyroid gland - a thyroidectomy - involves the removal of all or part of the thyroid gland. This is now achieved with small cosmetic scars usually and just one night in hospital.
A total thyroidectomy is a procedure where all the thyroid gland is removed. This is the operation of choice in multinodular goiters, patients with Graves’ disease where surgery has been chosen over radioiodine, and it is mandatory in all thyroid but the smallest cancers. In the case of thyroidectomies for thyroid cancer the operation may also involve removal of tissue surrounding the thyroid gland and lymph nodes that may have been involved in the cancer.
Thyroid surgery is safe when performed by experienced and appropriately trained specialist surgeons. Complications in thyroid surgery are infrequent and less likely to occur when surgery is undertaken by specialists in a team that regularly undertake thyroid surgery. The principle permanent problems that may be encountered after thyroid surgery are voice change or hoarseness and a low calcium leading to the need to take calcium and vitamin D supplements either short term or sometimes for life. Intraoperative nerve monitoring may be adopted during surgery but does not replace the need to identify and preserve the key nerves that control the voice during surgery. Bleeding, bruising and infection are all uncommon and should occur in less than 1% of cases.
Choosing your neck surgeon. Inevitably when requiring thyroid or parathyroid surgery patients wish to be treated by the best thyroid surgeon possible.
There is a strong link between training, practice volume, the experience of the surgeon and the best outcomes in thyroid and parathyroid surgery. Large studies from Germany and the USA have repeatedly demonstrated that surgeons performing less than 30 thyroidectomies per year are more likely to have complications following thyroid surgery. A study from the USA reinforces these findings suggesting that surgeons performing cumulatively more than 100 thyroidectomies and parathyroidectomies per year are most likely to achieve the best outcomes sought by the leading centers. It is therefore recommended that patients requiring thyroid surgery find a specialist surgeon that regularly undertake thyroid surgery in high volume. Such data is now available on national websites such as that of the American Association of Endocrine Surgeons (AAES).
The Surgeons I work most closely with are Dr. Hyde and Dr. Sherman at the “Surgical Associates of La Jolla”. They both are particularly meticulous in preparation, helping the patients decide what is best for them, and if surgery might be necessary they have an excellent record for parathyroid localization, and during surgery will routinely use intra-operative recurrent laryngeal nerve monitoring and intra-operative PTH measurement - their results are excellent.