It has two lobes and sits in front of the windpipe trachea. The voice box larynx sits just above the thyroid. The thyroid gland produces hormones that regulate the body's metabolic rate controlling heart, muscle and digestive function, brain development and bone maintenance.
Its correct functioning depends on a good supply of iodine from the diet. Cells producing thyroid hormones are very specialised in extracting and absorbing iodine from the blood and incorporate it into the thyroid hormones. The signal comes from a small gland located at the bottom of our brain called the pituitary gland. The pituitary gland produces and sends out a hormone called thyroid-stimulating hormone TSH.
TSH then tells the thyroid gland how much hormones to produce and secrete. There is a third actor involved in this communication. The pituitary gland responds either directly to the thyroid hormones in the blood, but it also responds to signals from the hypothalamus , which sits above the pituitary gland as part of your brain.
The hypothalamus releases its own hormone thyrotropin-releasing hormone TRH. The thyroid gland produces thyroxine referred to as T4 , which is a relatively inactive prohormone. The highly active hormone is triiodothyronine referred to as T3. Collectively, thyroxine and triiodothyronine are referred to as the thyroid hormones. Once secreted by the thyroid, specific enzymes in other tissues like the liver or kidneys may transform T4 in to the active hormone T3.
In addition, there are other hormone-producing cells within the thyroid gland called C-cells. These cells produce calcitonin. Calcitonin plays a role in regulating calcium and phosphate levels in the blood, which is important for your bone health and maintenance. Aging itself has only minor effects on the thyroid gland and thyroid hormones. As people get older, the thyroid gland shrinks and shifts lower in the neck.
The level of the thyroid hormone triiodothyronine T3 may fall slightly, but the speed of vital functions changes very little. However, thyroid disorders become more common with aging. Disorders that affect thyroid function, particularly hyperthyroidism Hyperthyroidism Hyperthyroidism is overactivity of the thyroid gland that leads to high levels of thyroid hormones and speeding up of vital body functions.
Graves disease is the most common cause of hyperthyroidism Facial expressions become dull, the voice These disorders often cause symptoms that are easily mistaken for symptoms of other conditions or even as signs of getting old. Increased or decreased thyroid function can dramatically worsen the way an older person feels and can greatly diminish the ability to carry out daily activities.
For these reasons, the great masqueraders must be unmasked and recognized for what they are so that they can be effectively treated. Screening older people for hyperthyroidism and hypothyroidism is helpful. Some experts recommend measuring the level of thyroid-stimulating hormone in the blood in people over 65 every 5 years.
Instead, T4 is converted into T3, the more active hormone. The conversion of T4 to T3 occurs in the liver and other tissues. Most of the T4 and T3 in the bloodstream is carried bound to a protein called thyroxine-binding globulin.
Only a little of the T4 and T3 are circulating free in the blood. However, it is this free hormone that is active. When the free hormone is used by the body, some of the bound hormone is released from the binding protein.
To produce thyroid hormones, the thyroid gland needs iodine Iodine Deficiency Iodine deficiency, which is common worldwide, can lead to enlargement of the thyroid gland. The thyroid gland contains most of the iodine in the body. Iodine in the thyroid gland is necessary The thyroid gland traps iodine and processes it into thyroid hormones. As thyroid hormones are used, some of the iodine contained in the hormones is released, returns to the thyroid gland, and is recycled to produce more thyroid hormones.
About 50 percent of people will have nodules that are too tiny to feel. The nodules can be solid or fluid-filled. Most are benign, but they can also be cancerous in a small percentage of cases. As with other thyroid-related problems, nodules are more common in women than men, and the risk in both sexes increases with age. However, if they grow large enough, they can cause swelling in your neck and lead to breathing and swallowing difficulties, pain , and goiter.
Some nodules produce thyroid hormone, causing abnormally high levels in the bloodstream. When this happens, symptoms are similar to those of hyperthyroidism and can include:. This includes:. Most nodules are detected during a normal physical exam. Once a nodule is detected, other procedures — a TSH test and a thyroid scan — can check for hyperthyroidism or hypothyroidism.
A fine needle aspiration biopsy is used to take a sample of cells from the nodule and determine whether the nodule is cancerous. Your doctor may do another biopsy and recommend radioactive iodine to shrink the nodules if it grows.
Cancerous nodules are pretty rare — according to the National Cancer Institute , thyroid cancer affects less than 4 percent of the population. The treatment your doctor recommends will vary depending on the type of tumor. Removing the thyroid through surgery is usually the treatment of choice. Radiation therapy is sometimes used with or without surgery.
Chemotherapy is often required if the cancer spreads to other parts of the body. Sometimes children are born with a thyroid problem. In other cases, surgery, disease, or treatment for another condition causes it.
The main symptom of a thyroid nodule in a child is a lump in the neck. The incidence is slightly higher in teens, with a rate of about 15 cases per million in to year-olds. In developing countries, hypothyroidism is often caused by iodine deficiency. However, thanks to the addition of iodine to table salt, this deficiency is rare in the United States. You can set off an overactive thyroid by taking too much thyroid hormone. In rare cases, your thyroid can become overactive if you eat too many foods that contain iodine, such as table salt, fish, and seaweed.
Though you may not be able to prevent thyroid disease, you can prevent its complications by getting diagnosed right away and following the treatment your doctor prescribes. The superior thyroid artery is located within the neck. The inferior thyroid vein may refer to any of the two, three or four veins that make up the venous plexus, an intricate system of interconnected veins…. Testing the level of thyroid stimulating hormone TSH in your blood can help your doctor figure out if your thyroid is overactive or underactive.
TSH tells your thyroid to make thyroid hormones. Depending on the results, your doctor might do another blood test to check levels of one or both thyroid hormones in your blood. Radioactive iodine uptake test. For this test, you swallow a liquid or capsule that holds a small dose of radioactive iodine radioiodine. The radioiodine collects in your thyroid because your thyroid uses iodine to make thyroid hormone. Thyroid scan. A thyroid scan uses the same radioiodine dose that was given by mouth for your uptake test.
You lie on a table while a special camera makes an image of your thyroid on a computer screen. This test shows the pattern of iodine uptake in the thyroid. Three types of nodules show up in this test: "Hot" nodules. These thyroid nodules show up on the scan more brightly than normal thyroid nodules. They take up more radioiodine than the surrounding thyroid. They also make more hormone than normal thyroids. These nodules take up the same amount of radioiodine as normal thyroid and make a normal amount of hormones.
These nodules show up as as dark areas on the scan. They do not take up much radioiodine and do not make thyroid hormones.
Many nodules are cold. The thyroid ultrasound uses sound waves to make a picture of the thyroid on a computer screen. This test can help your doctor tell what type of nodule you have and how large it is. You may need more thyroid ultrasounds over time to see if your nodule is growing or shrinking.
Thyroid fine needle biopsy. This test tells whether thyroid nodules have normal cells in them. Your doctor may numb an area on your neck. Your doctor will then stick a very thin needle into the thyroid to take out some cells and fluid. A doctor will then look at the cells under a microscope to see if they are normal. Cells that are not normal could mean thyroid cancer. Can thyroid disease cause problems getting pregnant? How does thyroid disease affect pregnancy?
Hyperthyroidism that is not treated with medicine during pregnancy can cause: 4 Premature birth birth of the baby before 39 to 40 weeks, or full-term Preeclampsia, pre-ee-CLAMP-see-uh a serious condition starting after 20 weeks of pregnancy. Preeclampsia causes high blood pressure and problems with the kidneys and other organs. The only cure for preeclampsia is childbirth. Thyroid storm sudden, severe worsening of symptoms Fast heart rate in the newborn, which can lead to heart failure, poor weight gain, or an enlarged thyroid that can make it hard to breathe Low birth weight smaller than 5 pounds Miscarriage Hypothyroidism that is not treated with medicine during pregnancy can cause: 4 Anemia lower than normal number of healthy red blood cells Preeclampsia Low birth weight smaller than 5 pounds Miscarriage Stillbirth Problems with the baby's growth and brain development.
Did we answer your question about thyroid diseases? Phone Number: Sources American Thyroid Association Prevalence and Impact of Thyroid Disease U. Preventive Services Task Force. Screening for Thyroid Disease Balovich, M. Pregnancy and Thyroid Disease. De Groot, L. The incidence of thyroid disorders in the community: a twenty-year follow-up of the Whickham Survey. Clin Endocrinol Oxf ; 43 1 — Accessed from: Vanderpump, M. The epidemiology of thyroid disease.
British Medical Bulletin; 99 1 : 39— Mazzaferri EL. Management of a solitary thyroid nodule. N Engl J Med. American Thyroid Association. Thyroid nodules. Rahib, L. Cancer Research; 74 11 : — National Cancer Institute. Thyroid Cancer. Bomeli, S. Evaluation of a Thyroid Nodule.
Otolarnygol Clin North Am; 43 2 : — Skarulis, M. Stack, Jr.
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