Thyroid disease is a medical condition that affects the function of the thyroid gland (the endocrine organ found on the front of the neck that produces thyroid hormone). The symptoms of thyroid disease vary depending on the type. There are four common types: 1) hypothyroidism (low function) caused by not having enough thyroid hormone; 2) hyperthyroidism (high function) caused by too much thyroid hormone; 3) structural abnormalities, most often in the form of enlarged thyroid gland; and 4) tumors that can be benign or cancerous. It is also possible to have an abnormal thyroid function test without any clinical symptoms. Common hypothyroid symptoms include fatigue, low energy, weight, inability to tolerate cold, slow heart rate, dry skin and constipation. Common hyperthyroid symptoms include irritability, weight loss, rapid heartbeat, heat intolerance, diarrhea, and thyroid enlargement. In both hypothyroidism and hyperthyroidism, there may be swelling of the neck, also known as mumps.
Diagnosis can often be done through laboratory tests. The first is thyroid-stimulating hormone (TSH), which is generally below normal in hyperthyroidism and above normal in hypothyroidism. Other useful laboratory tests are free protein-free or T4-free thyroxine. Total and free triiodothyronine (T3) levels are used less frequently. Anti-thyroid autoantibodies can also be used, where an increase in anti-thyroglobulin and anti-thyroid peroxidase antibodies are commonly found in hypothyroidism from Hashimoto's thyroiditis and TSH receptor antibodies found in hyperthyroidism caused by Graves' disease. Procedures such as ultrasound, biopsy and radioiodine scans and absorption research can also be used to aid diagnosis.
Treatment of thyroid disease varies based on the disorder. Levothyroxine is a mainstay of care for people with hypothyroidism, while people with hyperthyroidism caused by Graves' disease can be managed with iodine therapy, antithyroid drugs, or surgical removal of the thyroid gland. Thyroid surgery can also be performed to remove thyroid or lobe nodules for biopsy, or if there are unsightly mumps or blocking nearby structures.
Hypothyroidism affects 3-10% percent of adults, with a higher incidence in women and the elderly. It is estimated that one third of the world's population currently live in low-level iodine-level regions, making the most common iodine deficiency of hypothyroidism and endemic goitre. In areas of severe iodine deficiency, the prevalence of mumps is as high as 80%. In areas where iodine deficiency is not found, the most common type of hypothyroidism is an autoimmune subtype called Hashimoto's thyroiditis, with a 1-2% prevalence. As for hyperthyroidism, Graves' disease, other autoimmune conditions, is the most common type with a prevalence of 0.5% in males and 3% in females. Although thyroid nodules are common, thyroid cancer is rare. Thyroid cancer accounts for less than 1% of all cancers in the UK, although it is the most common endocrine tumor and forms over 90% of all endocrine gland cancers.
Video Thyroid disease
Signs and symptoms
The symptoms of the condition vary with the type: hypo-vs hyperthyroidism, which is described further below.
Possible symptoms of hypothyroidism are:
Possible symptoms of hyperthyroidism are:
Note: Certain symptoms and physical changes can be seen in hypothyroidism and hyperthyroidism - fatigue, fine/thinning hair, irregularity of the menstrual cycle, muscle weakness (myalgia), and various forms of myxedema.
Maps Thyroid disease
Disease
Low function
Hypothyroidism is a condition in which the body does not produce enough thyroid hormone, or is unable to respond/utilize the existing thyroid hormone properly. Main categories are:
- Thyroiditis: inflammation of the thyroid gland
- Hashimoto/Hashimoto's thyroiditis disease
- Thyroiditis Ord
- Postpartum thyroiditis
- Silent thyroiditis
- Acute thyroiditis
- Riedel thyroiditis (the majority of cases do not affect thyroid function, but about 30% of cases cause hypothyroidism)
- Iatrogenic hypothyroidism
- Postoperative hypothyroidism
- Hypothyroidism induced by drugs or radiation
- Thyroid hormone hormone
- Euthyroid sick syndrome
- Congenital hypothyroidism: untreated, untreated thyroid hormone deficiency can cause cretinism
High function
Hyperthyroidism is a condition in which the body produces too much thyroid hormone. The main hyperthyroid conditions are:
- Graves' Disease
- Toxic thyroid nodules
- Thyroid storm
- Nodular stroma is toxic (Plummer's disease)
- Hashitoxicosis: transient hyperthyroidism that can occur in Hashimoto's thyroiditis
Structural abnormalities
- Mumps: an abnormal enlargement of the thyroid gland
- Mumps endemic
- Diffy goiter
- Multinodular goiter
- Linguistic thyroid
- Thyroglossal duct sacs
Tumor
- Thyroid adenoma: benign/non-cancerous tumor
- Thyroid cancer
- Papiler
- Follicular
- Medal
- Anaplastik
- Lymphoma and metastases from elsewhere (rarely)
Drug side effects
Certain medications can have unwanted side effects that affect thyroid function. While some drugs can cause significant hypothyroidism or hyperthyroidism and those at risk should be carefully monitored, some medications may affect laboratory tests of the thyroid hormone without causing symptoms or clinical changes, and may not require treatment. The following medications have been linked to various forms of thyroid disease:
- Amiodarone (more often can cause hypothyroidism, but may be associated with some type of hyperthyroidism)
- Lithium salt (hypothyroidism)
- Several types of interferon and IL-2 (thyroiditis)
- Glucocorticoids, dopamine agonists, and somatostatin analogues (TSH block, which can cause hypothyroidism)
Diagnosis
The diagnosis of thyroid disease depends on the symptoms and whether there is a thyroid nodule or not. Most patients will receive a blood test. Others may require ultrasound examination, biopsy or radioiodine scanning and absorption.
Blood tests
Thyroid function test
There are several hormones that can be measured in the blood to determine how the thyroid gland works. These include thyroid hormone triiodothyronine (T3) and thyroxine precursors (T4), which are produced by the thyroid gland. Thyroid-stimulating hormone (TSH) is another important hormone secreted by anterior pituitary cells in the brain. Its main function is to increase the production of T3 and T4 by the thyroid gland.
The most useful function of the thyroid gland is serum thyroid-stimulating hormone (TSH) level. The TSH level is determined by a classical negative feedback system where high levels of T3 and T4 suppress TSH production, and low levels of T3 and T4 increase TSH production. TSH levels are so often used by doctors as screening tests, where the first approach is to determine whether TSH is increased, suppressed, or normal.
- Increased levels of TSH may indicate inadequate production of thyroid hormone (hypothyroidism)
- Depressed TSH levels may indicate excessive production of thyroid hormone (hyperthyroidism)
Because a single abnormal TSH level can be misleading, T3 and T4 levels should be measured in the blood to better confirm the diagnosis. When circulating in the body, T3 and T4 are bound to transport proteins. Only a small fraction of circulating thyroid hormones are unbound or free, and thus biologically active. T3 and T4 levels can be measured as free T3 and T4, or total T3 and T4, which consider hormone-free other than protein-bound hormones. Free T3 and T4 measurements are important because certain drugs and diseases can affect the concentration of transport proteins, resulting in totally different free thyroid hormone levels. There are different guidelines for measuring T3 and T4.
- The free T4 level should be measured in the evaluation of hypothyroidism, and the low free T4 makes the diagnosis. T3 levels are generally not measured in the evaluation of hypothyroidism.
- Free T4 and total T3 can be measured when hyperthyroidism has a high suspicion as it will improve diagnostic accuracy. T4 is free, total T3 or both are elevated and serum TSH is below normal in hyperthyroidism. If hyperthyroidism is mild, only serum T3 may be elevated and serum TSH may be low or may be undetectable in the blood.
- The free T4 level may also be tested in patients with symptomatic hyper and hypothyroidism, even if TSH is normal.
Antithyroid antibodies
Autoantibodies to the thyroid gland can be detected in various disease states. There are several anti-thyroid antibodies, including anti-thyroglobulin antibodies (TgAb), anti-microsomal/anti-thyroid peroxidase antibodies (TPOAb), and TSH (TSHRAb) receptor antibodies. Increased anti-thyroglobulin (TgAb) and anti-thyroid peroxidase antibodies (TPOAb) can be found in patients with Hashimoto's thyroiditis, the most common type of autoimmune hypothyroidism. TPOAb levels have also been found to be elevated in patients who present with subclinical hypothyroidism (where TSH increases, but free T4 is normal), and may help predict progression to overt hypothyroidism. The Association of the American Thyroid Association thus recommends measurement of TPOAb levels when evaluating subclinical hypothyroidism or when trying to identify whether nodular thyroid disease is caused by autoimmune thyroid disease.
Other markers
- There are two markers for cancer that are derived from the thyroid.
- Thyroglobulin (TG) levels can be elevated in differentiation of papillary adenocarcinoma or well-differentiated follicles. It is often used to provide information about residual, recurrent or metastatic diseases in patients with differentiated thyroid cancers. However, serum TG levels may be elevated in most thyroid disease. Routine measurements of serum TG for evaluation of thyroid nodules are thus not currently recommended by the American Thyroid Association.
- Increased levels of calcitonin in the blood have been shown to be associated with a rare medullary thyroid cancer. However, measurement of calcitonin levels as a diagnostic tool is currently controversial because of high or low false calcitonin levels in various diseases other than medullary thyroid cancer.
- Very rarely, TBG and transthyretin levels may be abnormal; this is not routinely tested.
- To distinguish between different types of hypothyroidism, special tests may be used. Thyrotropin-releasing hormone (TRH) is injected into the body through the blood vessels. This hormone is naturally secreted by the hypothalamus and stimulates the pituitary gland. The pituitary gland responds by releasing thyroid stimulating hormone (TSH). A large number of externally administered TRHs may suppress subsequent release of TSH. The amount of these discharges is exaggerated in primary hypothyroidism, major depression, cocaine dependence, amphetamine dependence and chronic abuse of phencyclidine. There is a failure to suppress the manic phase of bipolar disorder.
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Many people can develop thyroid nodules at some point in their lives. Although many are experiencing this concern that it is thyroid cancer, there are many causes of benign nodules and not cancer. If the nodule may be present, the doctor may order a thyroid function test to determine whether the activity of the thyroid gland is being affected. If more information is needed after clinical examination and laboratory tests, medical ultrasonography may help determine the nature of thyroid nodules. There are some important differences in benign nodules that are benign and distinctive in cancers that can be particularly detectable by high frequency sound waves in ultrasound scans. Ultrasound can also find nodules that are too small for the doctor to feel on physical examination, and can indicate whether the nodules are mainly solid, liquid (cystic), or a mixture of both. This is a frequent imaging process in a doctor's office, painless, and does not expose an individual to any radiation.
The main characteristics that can help distinguish benign vs. benign nodules (cancer) on ultrasound are as follows:
Although ultrasonography is a very important diagnostic tool, this method is not always able to separate the benign from malignant nodules with certainty. In suspicious cases, tissue samples are often obtained by biopsy for microscopic examination.
Radioiodine scanning and retrieval
Thyroid scintigraphy, in which the thyroid is imaged with the help of radioactive iodine (usually iodine-123, which does not harm thyroid cells, or rarely, iodine-131), is performed in the nuclear medicine department of a hospital or clinic. Radioiodine collects in the thyroid gland before it is excreted in the urine. While in the thyroid, radioactive emission can be detected by the camera, resulting in abrasive image of the form (a radioiodine scan ) and tissue activity (a radioiodine absorption ) of the thyroid gland.
A normal radiiodine scan shows even absorption and activity throughout the gland. Irregular uptake may reflect abnormal or abnormal glands, or may indicate that some of the glands are overactive or inactive. For example, overactive ("hot") nodules - to the point of suppressing glandular activity - are usually a thyrotoxic adenoma, a rarely malignant form of hyperthyroidism. Instead, it found that a substantial part of the inactive thyroid ("cold") may indicate a malfunctioning tissue area, such as thyroid cancer.
The amount of radioactivity can be quantified and serves as an indicator of metabolic activity of the gland. The normal quantification of radioiodine absorption shows that about 8-35% of the administered dose can be detected in the thyroid 24 hours later. Too active or insufficient gland activity, as is possible with hyperthyroidism or hypothyroidism, is usually reflected in an increase or decrease in radioiodine uptake. Different patterns may occur with different causes of hypo or hyperthyroidism.
Biopsy
Medical biopsy refers to tissue sampling for examination under a microscope or other testing, usually to differentiate cancer from non-cancerous conditions. Thyroid tissue can be obtained for biopsy with fine needle aspiration (FNA) or by surgery.
Fine needle aspiration has the advantage of being a safer, safer, outpatient procedure that is safer and cheaper than surgery and leaves no visible scars. Needle biopsy became widely used in the 1980s, but it was recognized that the accuracy of cancer identification was good, but not perfect. The accuracy of the diagnosis depends on taking tissue from all suspicious areas of the abnormal thyroid gland. The reliability of fine needle aspiration increases when sampling can be guided by ultrasound, and over the past 15 years, this has been the preferred method for thyroid biopsy in North America.
Treatment
Medication
Levotyroxine is a stereoisomeric thyroxine (T4) that is degraded much more slowly and can be administered once daily in patients with hypothyroidism. The natural thyroid hormone of pigs is sometimes also used, especially for people who can not tolerate synthetic versions. Hyperthyroidism caused by Graves' disease may be treated with thioamide propylthiouracil, carbimazole or methimazole, or rarely with Lugol's solution. In addition, hyperthyroidism and thyroid tumors can be treated with radioactive iodine. Injection of ethanol for the treatment of recurrent thyroid cysts and metastatic thyroid cancer in lymph nodes can also be an alternative for surgery.
Surgery
Thyroid surgery is done for various reasons. A thyroid nodule or lobe is sometimes removed for biopsy or because of an autonomically functioning adenoma that causes hyperthyroidism. Most thyroid can be removed ( subtotal thyroidectomy) to treat Graves' hyperthyroidism disease, or to remove unsightly mumps or override vital structures.
The complete thyroidectomy of the entire thyroid, including associated lymph nodes, is the preferred treatment for thyroid cancer. The removal of most of the thyroid gland usually results in hypothyroidism unless the person takes a thyroid hormone replacement. As a result, individuals who have undergone total thyroidectomy are usually placed on thyroid hormone replacement (eg Levothyroxine) for the rest of their lives. Higher than normal doses are often given to prevent recurrence.
If the thyroid gland should be removed surgically, care should be taken to avoid damage to adjacent structures, parathyroid glands and recurrent laryngeal nerves. Both are susceptible to accidental displacement and/or injury during thyroid surgery.
Parathyroid glands produce parathyroid hormone (PTH), the hormone needed to maintain adequate amounts of calcium in the blood. Removal causes hypoparathyroidism and the need for additional calcium and vitamin D every day. In the event that the blood supply to one of the parathyroid glands is threatened by surgery, the involved parathyroid gland (s) can be reincorporated in the surrounding muscle tissue.
The recurrent laryngeal nerves provide motor control for all external larynx muscles except for the cricothyroid muscle, which also travels along the posterior thyroid. Unintentional laseration of either of two or both recurrent laryngeal nerves may result in paralysis of the vocal cords and associated muscles, altering the sound quality.
Radioiodine
Radioiodine therapy with iodine-131 can be used to shrink the thyroid gland (for example, in cases of large goitre causing symptoms but not cancerous - after evaluation and biopsy of suspicious nodules has been done), or to destroy hyperactive cell- thyroid cells (for example, in cases of thyroid cancer). Iodine absorption can be high in countries with iodine deficiency, but low in sufficient iodine countries. To improve iodine-131 uptake by the thyroid and allow for more successful treatments, TSH is raised before therapy to stimulate the existing thyroid cells. This is done either with the withdrawal of thyroid hormone or recombinant human TSH injections (Thyrogen), released in the United States in 1999. Thyroid injection can be reported to increase up to 50-60% uptake. The treatment of radioiodin can also cause hypothyroidism (which is sometimes the final goal of treatment) and, although rarely, pain syndrome (due to thyroiditis radiation).
References
External links
- Thyroid disease in Curlie (based on DMOZ)
- Medline Plus Medical Encyclopedia entries for Thyroid Disease
- National Institutes of Health
Source of the article : Wikipedia
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