What You Need To Know About Thyroid Disease
The thyroid gland is a small, gland located in the base of the neck. It plays a huge role in our body, influencing the function of many of the body’s most important organs, including the heart, brain, liver, kidneys and skin.
I use this example with my patients to explain the role of the thyroid gland:
Think of your thyroid as a car engine that controls how your body functions. An engine produces the necessary energy for a car to operate in a certain manner. In the same way, the thyroid gland produces enough thyroid hormone to prompt your body to perform functions in a certain manner. Just as a car cannot produce energy without gas, your thyroid needs fuel to produce thyroid hormone. Your thyroid’s fuel is iodine. The thyroid extracts iodine from the bloodstream and uses it to make two thyroid hormones: T4 (contains four iodine atoms) and T3 (contains three iodine atoms). T3 is made from T4 when one iodine is removed, a conversion that occurs mostly outside the thyroid in organs and tissues where T3 is the primary thyroid hormone that is used. When T4 is produced, it is stored within the thyroid as a reserve for later use. A small amount of T3 is also produced and stored in the thyroid. When your body needs thyroid hormone, it is secreted into your bloodstream in quantities set to meet the needs of your cells. Your car engine produces energy, but you tell it how fast to go by stepping on the accelerator. The thyroid gets its instruction from the pituitary gland, which is located in your brain. These instructions come in the form of thyroid-stimulating hormone (TSH). TSH levels rise or fall depending on whether enough thyroid hormone is produced to meet your body’s needs. Higher levels of TSH prompt the thyroid to produce more thyroid hormone. Conversely, low TSH levels signal the thyroid to slow down production.
When Things Go Wrong
Normally, the thyroid produces just the right amount of hormone to keep your body running smoothly. TSH levels remain fairly constant. But even the best systems are subject to interference. When outside influences such as disease, damage to the thyroid or certain medicines inhibit proper communication, your thyroid might not produce enough hormone. This slows down all of your body’s functions – known as hypothyroidism or underactive thyroid. I like to use the term ‘suboptimal’ thyroid function. Your thyroid could also produce too much hormone which would send your systems into overdrive, a condition called hyperthyroidism or overactive thyroid. I like to use the term overactive thyroid. When considering thyroid disease, doctors ask two main questions: First, is the thyroid gland inappropriately producing an abnormal amount of thyroid hormone? And second, is there a structural change in the thyroid, such as a lump (a nodule) or an enlargement (a goiter)? Though one of these characteristics does not necessarily imply that the other is present nor do they diagnose hypo- or hyperthyroidism.
Out of Gas
Sometimes the thyroid can’t meet your body’s demands for thyroid hormone, even though TSH levels increase. As your body slows down, you may feel cold, tired and even depressed. You may gain weight, even though you’re eating less and exercising. There could be a number of reasons why your thyroid is not performing well. For example, if your body isn’t getting enough iodine, your thyroid can’t make enough thyroid hormone, but it will try to respond to rising TSH levels by working harder and harder anyway.
Causes of Hypothyroidism
- Autoimmune thyroiditis: When your thyroid comes under attack by your body’s immune system. Normally, antibodies protect you from infection or inflammation. But in this condition, called Hashimoto’s thyroiditis, your antibodies mistake your thyroid for a foreign invader. Hashimoto’s generally involves the presence of two types of antibodies called antithyroid peroxidase (anti-TPO) and antithyroglobulin (anti-TG) antibodies. These antibodies lead to destruction of the thyroid by the immune system. Hashimoto’s thyroiditis results from an abnormal immune response are called autoimmune diseases. Hashimoto’s thyroiditis is only one form of thyroiditis —an inflammation of the thyroid—that causes hypothyroidism. Other autoimmune diseases may be associated with this disorder, and additional family members may also be affected.
- Central or pituitary hypothyroidism: Any destructive disease of the pituitary gland or hypothalamus, which sits just above the pituitary gland, may cause damage to the cells that secrete TSH, which stimulates the thyroid to produce normal amounts of thyroid hormone. This is a rare cause of hypothyroidism.
- Congenital hypothyroidism: An infant may be born with an inadequate amount of thyroid tissue or an enzyme defect that does not allow normal thyroid hormone production. If this condition is not treated promptly, physical stunting and/or mental damage may develop.
- Medications: Lithium, high doses of iodine and Amiodarone, for example.
- Postpartum thyroiditis: 5-10% of women develop mild to moderate hyperthyroidism within months of giving birth. Hyperthyroidism in this condition usually lasts for approximately 1-2 months. It is often followed by several months of hypothyroidism. Most women will eventually recover normal thyroid function. In some cases, however, the thyroid gland does not heal, so the hypothyroidism becomes permanent and requires lifelong thyroid hormone replacement. This condition may recur in subsequent pregnancies.
- Radioactive iodine treatment: Hypothyroidism frequently develops as a desired therapeutic goal after the use of radioactive iodine treatment for hyperthyroidism.
- Silent Thyroiditis: This condition appears to be the same as postpartum thyroiditis but not related to pregnancy.
- Subacute thyroiditis: This condition may follow a viral infection and is characterized by painful thyroid gland enlargement and inflammation, which results in the release of large amounts of thyroid hormone into the blood. This condition usually resolves spontaneously. The thyroid usually heals itself over several months.
- Thyroid surgery: Hypothyroidism may be related to surgery on the thyroid gland, especially if most of the thyroid has been removed.
Signs & Symptoms of Hypothyroidism
In its earliest stage, hypothyroidism may cause few symptoms, since the body has the ability to partially compensate for a failing thyroid gland by increasing the stimulation to it, much like pressing down on the accelerator when climbing a hill to keep the car going the same speed. As thyroid hormone production decreases and the body’s metabolism slows, a variety of features may result.
- Pervasive fatigue
- Difficulty with learning
- Dry, brittle hair and nails
- Dry, itchy skin
- Puffy face
- Sore muscles
- Weight gain and fluid retention
- Heavy and/or irregular menstrual flow
- Increased frequency of miscarriages
- Increased sensitivity to many medications
Characteristic symptoms and physical signs can signal hypothyroidism. However, the condition may develop so slowly that many patients do not realize that their body has changed, so it is critically important to perform diagnostic laboratory tests to confirm the diagnosis and to determine the cause of hypothyroidism.
Hypothyroidism is generally treated with a daily medication. There are multiple types of thyroid medication. Not everyone respond the same to each medication, and not every medication is appropriate for a particular type of thyroid disease An experienced physician can prescribe the correct form and dosage to return the thyroid balance to normal. Thyroid hormone acts very slowly in some parts of the body, so it may take several months after treatment for some features to improve.
It is extremely important that women planning to become pregnant are kept well adjusted, since hypothyroidism can affect the development of the baby. During pregnancy, thyroid hormone replacement requirements often change, so more frequent monitoring is necessary. Various medications and supplements (particularly iron) may affect the absorption of thyroid hormone; therefore, the levels may need more frequent monitoring during illness or change in medication and supplements. Thyroid hormone is critical for normal brain development in babies.
Since most cases of hypothyroidism are permanent and often progressive, it is usually necessary to treat this condition throughout one’s lifetime. Periodic monitoring of laboratory levels and clinical status are necessary to ensure that the proper dose is being given, since medication doses may have to be adjusted from time to time. Optimal adjustment of thyroid hormone dosage is critical, since the body is very sensitive to even small changes in thyroid hormone levels.
Revved Up – Hyperthyroidism
Hyperthyroidism develops when the body is exposed to excessive amounts of thyroid hormone. This disorder occurs in almost one percent of all Americans and affects women five to 10 times more often than men. In its mildest form, hyperthyroidism may not cause recognizable symptoms. More often, however, the symptoms are discomforting, disabling or even life-threatening.
Causes of Hyperthyroidism
- Graves’ Disease: Graves’ disease is an autoimmune disorder that frequently results in thyroid enlargement and hyperthyroidism. In some patients, swelling of the muscles and other tissues around the eyes may develop. This is characterized by swollen, bulging, red eyes; widely open eyelids; and double vision. In its most severe form, diminished visual acuity may be present. As with Hashimoto’s thyroiditis, antibodies attack the thyroid, but in this case they stimulate the thyroid to overproduce thyroid hormone. The antibodies present in Graves’ disease are generally thyrotropin receptor antibodies (TRAb), including one kind known as thyroid-stimulating immunoglobulins (TSIs). They work by mimicking TSH, attaching to the TSH receptor on the thyroid gland and confusing the thyroid into producing too much hormone. Like other autoimmune diseases, this condition tends to affect multiple family members. It is much more common in women than in men and tends to occur in younger patients.
- Postpartum Thyroiditis: 5-10% of women develop mild to moderate hyperthyroidism within months of giving birth. Hyperthyroidism in this condition usually lasts for 1-2 months. It is often followed by several months of hypothyroidism, but most women will eventually recover normal thyroid function. In some cases, however, the thyroid gland does not heal, so the hypothyroidism becomes permanent and requires lifelong thyroid hormone replacement. This condition may occur again with subsequent pregnancies.
- Silent Thyroiditis: Transient (temporary) hyperthyroidism can be caused by silent thyroiditis, a condition similar to postpartum thyroiditis, but is not related to pregnancy. It is not accompanied by a painful thyroid gland.
- Subacute Thyroiditis: This condition may follow a viral infection and is characterized by painful thyroid gland enlargement and inflammation, which results in the release of large amounts of thyroid hormones into the blood. This condition usually resolves spontaneously over several months, but often not before a temporary period of low thyroid hormone production occurs.
- Toxic Multinodular Goiter: Multiple nodules in the thyroid can produce excess thyroid hormone, causing hyperthyroidism. Typically diagnosed in patients over the age of 50, this disorder is more likely to affect heart rhythm. In many cases, the person has had the goiter for many years before it becomes overactive.
- Toxic Nodule: A single nodule or lump in the thyroid can produce more thyroid hormone than the body requires and lead to hyperthyroidism.
- Excessive Iodine Ingestion: Various sources of high iodine concentrations, such as kelp tablets, some expectorants, amiodarone and x-ray dyes may occasionally cause hyperthyroidism in patients who are prone to it.
- Overmedication with thyroid hormone: Patients who receive excessive thyroxine replacement treatment can develop hyperthyroidism. They should have their thyroid hormone dosage evaluated routinely and should NEVER give themselves “extra” doses.
Signs & Symptoms of Hyperthyroidism
When hyperthyroidism develops, a goiter (enlargement of the thyroid) is usually (but not always) present and may be associated with some or many of the following features:
- Fast heart rate, often more than 100 beats per minute
- Becoming anxious, irritable, argumentative
- Trembling hand
- Weight loss, despite eating the same amount or even more than usua
- Intolerance of warm temperatures and increased likelihood to perspire
- Loss of scalp hair
- Tendency of fingernails to separate from the nail bed
- Muscle weakness, especially of the upper arms and thighs
- Loose and frequent bowel movements
- Smooth skin
- Change in menstrual pattern
- Increased likelihood for miscarriage
- Prominent “stare” of the eyes
- Protrusion of the eyes, with or without double vision (in patients with Graves’ disease)
- Irregular heart rhythm, especially in patients older than 60 years of age
- Accelerated loss of calcium from bones, which increases the risk of osteoporosis and fractures
Characteristic symptoms and physical signs of the disease can be detected by a trained physician. In addition, tests can be used to confirm the diagnosis and to determine the cause.
Two drugs are available for treating hyperthyroidism: propylthiouracil (PTU) and methimazole. Except for early pregnancy, methimazole is preferred. These medications control hyperthyroidism by slowing thyroid hormone production. They may take several months to normalize thyroid hormone levels.
Radioactive Iodine Treatment
Iodine is an essential in the production of thyroid hormone. Each molecule of thyroid hormone contains either four (T4) or three (T3) molecules of iodine. Since most overactive thyroid glands are hungry for iodine, it was discovered that the thyroid could be “tricked” into destroying itself by feeding it radioactive iodine. The radioactive iodine is given by mouth, usually in capsule form. Maximal benefit is usually noted within 3-6 months. Most physicians strive to completely destroy the thyroid gland with a single dose of radioiodine. This results in the intentional development of an underactive thyroid state (hypothyroidism), which is easily, predictably and inexpensively corrected by lifelong daily use of oral thyroid hormone replacement therapy.
Thousands of patients have received radioiodine treatment. The treatment is a very safe, simple and reliably effective. Because of this, it is considered by most thyroid specialists to be the treatment of choice for hyperthyroidism cases caused by overproduction of thyroid hormone.
Surgical Removal of the Thyroid
Although seldom used now as the preferred treatment for hyperthyroidism, surgically removing most(or all) of the thyroid gland may be recommended in certain situations. Surgery usually leads to permanent hypothyroidism and lifelong thyroid hormone replacement therapy.
A drug from the class of beta-adrenergic blocking agents (which decrease the effects of excess thyroid hormone) can temporarily control hyperthyroid symptoms until other therapies take effect. In cases where hyperthyroidism is caused by thyroiditis or excessive ingestion of either iodine or thyroid hormone, this may be the only type of treatment required. Also, iodine drops are prescribed when hyperthyroidism is severe or prior to undergoing surgery for Graves’ disease.
How common is thyroid disease?
Thyroid disease is more common than diabetes or heart disease. As many as 30 million Americans are affected by thyroid disease – and more than half of those people remain undiagnosed. Women are five times more likely than men to suffer from hypothyroidism.
How important is my thyroid in my overall well-being?
The thyroid gland produces thyroid hormone, which controls virtually every cell, tissue and organ in the body. Untreated thyroid disease may lead to elevated cholesterol levels and subsequent heart disease, as well as infertility and osteoporosis. Research also shows that there is a strong genetic link between thyroid disease and other autoimmune diseases, including types of diabetes, arthritis and anemia. Simply put, if your thyroid gland isn’t working properly, neither are you.
How do you know if you have a thyroid problem?
First, you must recognize the symptoms and risk factors of thyroid disease. Since many symptoms may be hidden or mimic other diseases and conditions, the best way to know for sure is to ask your doctor.
What are some of the reasons to consider a thyroid evaluation?
- Family history: If you have a first-degree relative (a parent, sibling or child) with thyroid disease, you would benefit from thyroid evaluation. Women are much more likely to be thyroid patients than men; however, the gene pool runs through both.
- Prescription medications: If you are taking Lithium or Amiodarone, you should consider a thyroid evaluation.
- Radiation therapy to the head or neck: If you have had any of the following radiation therapies, you should consider a thyroid evaluation: radiation therapy for tonsils, radiation therapy for an enlarged thymus, or radiation therapy for acne.
- Chernobyl: If you lived near Chernobyl at the time of the 1986 nuclear accident, you should consider a thyroid evaluation.
A thyroid nodule is a lump in or on the thyroid gland. Thyroid nodules are common, but are usually not diagnosed. They are detected in about 6% percent of women and 1-2% of men. They are 10 times as common in older people. Sometimes several nodules will develop in the same person. Any time a lump is discovered in thyroid tissue, the possibility of malignancy (cancer) must be considered. Fortunately, the vast majority of thyroid nodules are benign (not cancerous).
Nodules can be caused by a simple overgrowth of “normal” thyroid tissue, fluid-filled cysts, inflammation (thyroiditis), or a tumor (either benign or cancerous).
Signs & Symptoms
Most patients with thyroid nodules have no symptoms. Many are found by chance on a routine physical exam or an imaging study of the neck done for unrelated reasons. A substantial number of nodules are first noticed by patients or those they know who see a lump in the front portion of the neck, which may or may not cause symptoms, such as a vague pressure sensation or discomfort when swallowing. Finding a lump in the neck should be brought to the attention of your physician, even in the absence of symptoms.
- Thyroid Scan: A picture of the thyroid gland taken after a small dose of a radioactive isotope has been injected or swallowed. The scan tells whether the nodule is hyperfunctioning (a “hot” nodule), or taking up more radioactivity than normal thyroid tissue does; taking up the same amount as normal tissue (a “warm” nodule); or taking up less (a “cold” nodule). Because cancer is rarely found in hot nodules, a scan showing a hot nodule eliminates the need for fine needle biopsy. If a hot nodule causes hyperthyroidism, it can be treated with radioiodine or surgery.
- Thyroid needle biopsy: A very thin needle takes a small sample of tissue from the nodule. This is a simple procedure performed in the physician’s office and patients can usually return to work or home afterward. A thyroid needle biopsy will provide sufficient information on which to base a treatment decision more than 75% of the time, eliminating the need for additional diagnostic studies. Use of fine needle biopsy has reduced the number of patients who have undergone unnecessary operations for benign nodules. However, about 10-20% of biopsy specimens are interpreted as inconclusive or inadequate – uncertain whether the nodule is cancerous or benign. In such cases, a physician who is experienced with thyroid disease can use other criteria to make a decision about whether or not to operate. The fine needle biopsy can be repeated in patients whose initial attempt failed to yield enough material to make a diagnosis. Many physicians use thyroid ultrasonography (ultrasound) to guide the needle’s placement.
- Thyroid ultrasonography: Obtaining pictures of the thyroid gland by using high-frequency sound waves to create detailed images of the thyroid. It can visualize nodules as small as 2-3 millimeters. Ultrasound distinguishes thyroid cysts (fluid-filled nodules) from solid nodules and help physicians identify nodules that are more likely to be cancerous. Thyroid ultrasonography is also utilized for guidance of a fine needle for aspirating thyroid nodules. Ultrasound guidance allows biopsy samples to be obtained from the solid portion of those nodules that are both solid and cystic, and it avoids getting a specimen from the surrounding normal thyroid tissue if the nodule is small. Even when a thyroid biopsy sample is reported as benign, the size of the nodule should be monitored. A thyroid ultrasound examination provides an objective and precise method for detection of a change in the size of the nodule. A nodule with a benign biopsy that is stable or decreasing in size is unlikely to be malignant or require surgical treatment.
Most patients who appear to have benign nodules require no specific treatment and can be followed by their physician. Some physicians prescribe thyroid medications with hopes of preventing nodule growth or reducing the size of cold nodules, while radioiodine may be used to treat hot nodules. If cancer is suspected, surgical treatment is recommended. The primary goal of therapy is to remove all thyroid nodules that are cancerous and, if malignancy is confirmed, remove the rest of the thyroid gland along with any abnormal lymph nodes. If surgery is not recommended, it is important to have regular follow-up of the nodule.