Overactivity of the Thyroid Gland

 

Hyperthyroidism is a large topic, so we have split it into four manageable sized portions.  This page introduces hyperthyroidism.  Subsequent pages are listed at the bottom which address more specific details of making the diagnosis of hyperthyroidism, the causes of hyperthyroidism, and different treatment options available for hyperthyroidism. 

 

In healthy people, the thyroid makes just the right amounts of two hormones, T4 and T3, which have iimportant actions throughout the body.  These hormones regulate many anspects of our metabolism, eventually affecting how many calories we burn, how warm we feel, and how much we weight.  In short, the thyroid "runs" our metabolism. 

 

These hormones also have direct effects on most organs, including the heart, which beats faster and harder under the influence of thyroid hormones.  Essentially, all cells in the body will respond to increases in thyroid hormones with an increase in the rate at which they conduct their business.  Hyperthryoidism is the medical term to describe the signs and symptoms associated with an over production of thryoid hormone.  For an overview of how thryoid hormone is produced and how much its production is regulated, check out our thyroid homone production page.

 

Hyperthryoidism is a condition caused by the effects of too much thyroid hormone on tissues of the body.  Although there are several causes of hyperthyroidism, most of the symptoms patients experience are the same regardless of the cause (see the list of symptoms below).

 

Because the body's metabolism is increased, patients often feel hotter than those around them

and can slowly lose weight even though they may be eating more. The weight issue is confusing sometimes since some

patients actually gain weight because of an increase in their appetite. Patients with hyperthyroidism usually experience

fatigue at the end of the day, but have trouble sleeping. Trembling of the hands and a hard or irregular heartbeat (called

palpitations) may develop. These individuals may become irritable and easily upset. When hyperthyroidism is severe,

patients can suffer shortness of breath, chest pain, and muscle weakness. Usually the symptoms of hyperthyroidism are

so gradual in their onset that patients don't realize the symptoms until they become more severe. This means the symptoms

may continue for weeks or months before patients fully realize that they are sick. In older people, some or all of

the typical symptoms of hyperthyroidism may be absent, and the patient may just lose weight or become depressed.

 

Common symptoms and signs of hyperthyroidism

 

     -  Palpitations                                                                                                                         -  Fast heart rate                                                                                       

     -  Heat intolerance                                                                                                               -  Trembling hands

     -  Nervousness                                                                                                                     -  Weight loss

     -  Insomnia                                                                                                                             -  Muscle weakness

     -  Breathlessness                                                                                                                -  Warm moist skin

     -  Increased bowel movements                                                                                       -  Hair loss

     -  Light or absent of menstrual periods                                                                         -  Staring gaze

     -  Fatigue

 

Remember, the words "signs" and "symptoms" have different medical meanings. Symptoms are those problems that a

patient notices or feels. Signs are those things that a physician can objectively detect or measure. For instance, a patient

will feel hot, this is a symptom. The physician will touch the patient's skin and note that it is warm and moist, this is a

sign.

 

Source: http://www.endocrineweb.com/hyperl.html

 

Inflammation of the Thyroid Gland

 

Thyroiditis is an inflammation (not an infection) of the thyroid gland. Several types of thyroiditis exist and the treatment is different for each.

 

Hashimoto's Thyroiditis

 

Hashimoto's thyroiditis, also called autoimmune or chronic lymphocytic thyroiditis, is the most common type of thyroiditis.  It is named after the Japanese physician, Hakaru Hashimoto, who first described it in 1912.

The thyroid gland is always enlarged, although only one side may be enlarged enough to feel. During the course of this disease, the cells of the thyroid becomes inefficient in converting iodine into thyroid hormone and "compensates" by enlarging (for a review of this process see our function page).

 

The radioactive iodine uptake may be paradoxically high while the patient is hypothyroid because the gland retains the ability to take-up or "trap" iodine even after it has lost its ability to produce thyroid hormone. As the disease progresses, the TSH increases since the pituitary is trying to induce the thyroid to make more hormone, the T4 falls since the thyroid can't make it, and the patient becomes hypothyroid. This sequence of events can occur over a relatively short span of a few weeks or may take several years.

 

-   Treatment should begin with thyroid hormone replacement. This prevents or corrects the hypothyroidism, and it also generally keeps the gland from getting larger.

-   In most cases, the thyroid gland will decrease in size once thyroid hormone replacement is started.

-   Thyroid antibodies are present in 95% of patients with Hashimoto's Thyroiditis and serve as a useful "marker" in identifying the disease without thyroid biopsy or surgery.

 

Thyroid antibodies may remain for years after the disease has been adequately treated and the patient is on thyroid hormone replacement.

 

De Quervain's Thyroiditis

 

De Quervain's thyroiditis (also called subacute or granulomatous thyroiditis) was first described in 1904 and is much less common than Hashimoto's thyroiditis. The thyroid gland generally swells rapidly and is very painful and tender. The gland discharges thyroid hormone into the blood and the patients become hyperthyroid; however, the gland quits taking up iodine (radioactive iodine uptake is very low), and the hyperthyroidism generally resolves over the next several weeks.

 

-   Patients frequently become ill with fever and prefer to be in bed.

-   Thyroid antibodies are not present in the blood, but the sedimentation rate (which measures inflammation) is very high.

-   Although this type of thyroiditis resembles an infection within the thyroid gland, no infectious agent has ever been identified, and antibiotics are of no use.

-   Treatment is usually bed rest and aspirin to reduce inflammation.

-   Occasionally cortisone (steroids, which reduce inflammation) and thyroid hormone (to "rest" the thyroid gland) may be used in prolonged cases.

-   Nearly all patients recover, and the thyroid gland returns to normal after several weeks or months.

-   A few patients will become hypothyroid once the inflammation settles down and therefore will need to stay on thyroid hormone replacement indefinitely.

-   Recurrences are uncommon.

 

Silent Thyroiditis

 

Silent thyroiditis is the third and least common type of thyroiditis. It was not recognized until the 1970s, although it

probably existed and was treated as Graves' disease before that. This type of thyroiditis resembles in part Hashimoto's thyroiditis and in part De Quervain's thyroiditis. The blood thyroid test is high and the radioactive iodine uptake is low (like De Quervain's thyroiditis), but there is no pain and needle biopsy resembles Hashimoto's thyroiditis.  The majority of patients have been young women following pregnancy. The disease usually needs no treatment, and 80% of patients show complete recovery and return of the thyroid gland to normal after three months. Symptoms are  similar to Graves' disease except milder. The thyroid gland is only slightly enlarged and exophthalmos (development of "bug eyes") does not occur. Treatment is usually bed rest with beta blockers to control palpitations (drugs to prevent rapid heart rates). Radioactive iodine, surgery, or antithyroid medication is never needed. A few patients have become permanently hypothyroid and needed to be placed on thyroid hormone.

 

Source:  http://www.endocrine.com/thyroiditis.html

Symptoms of Hyperthyroidism

 

-   Fatigue

-   Weakness

-   Weight gain or increased difficulty losing weight

-   Coarse, dry hair

-   Dry, rough pale skin

-   Hair loss

-   Cold intolerance (you can't tolerate cold temperatures like those around you)

-   Muscle cramps and frequent muscle aches

-   Constipation

-   Depression

 

Each individual patient may have any number of these symptoms, and they will vary with the severity of the thyroid

hormone deficiency and the length of time the body has been deprived of the proper amount of hormone.

 

You may have one of these symptoms as your main complaint, while another will not have that problem at all and

will be suffering from an entirely different symptom. Most people will have a combination of these symptoms. Occasionally,

some patients with hypothyroidism have no symptoms at all, or they are just so subtle that they go unnoticed.

 

If you have these symptoms, you need to discuss them with your doctor. Additionally, you may need to seek the

skills of an endocrinologist. If you have already been diagnosed and treated for hypothyroidism and continue to

have any or all of these symptoms, you need to discuss it with your physician.

 

Potential Dangers of Hypothyroidism

 

Because the body is expecting a certain amount of thyroid hormone the pituitary will make additional thyroid stimulating

hormone (TSH) in an attempt to entice the thyroid to produce more hormone. This constant bombardment with high levels of TSH may cause the thyroid gland to become enlarged and form a goiter (termed a "compensatory goiter").

 

Left untreated, the symptoms of hypothyroidism will usually progress. Rarely, complications can result in severe life-threatening depression, heart failure, or coma.

 

Hypothyroidism can often be diagnosed with a simple blood test. In some persons, however, it's not so simple and more detailed tests are needed. Most importantly, a good relationship with a good endocrinologist will almost surely be needed.

 

Hypothyroidism is completely treatable in many patients simply by taking a small pill once a day. However, this is a

simplified statement, and it's not always so easy. There are several types of thyroid hormone preparations and one

type of medicine will not be the best therapy for all patients. Many factors will go into the treatment of hypothyroidism

and it is different for everybody.

 

Sources:  http://www.endocrineweb.com/hypol.html

 

Too Little Thyroid Hormone

 

Hypothyroidism is a condition in which the body lacks sufficient thyroid hormone (T3 and

T4). Since the main purpose of thyroid hormone is to "run the body's metabolism," it is understandable that people with this condition will have symptoms associated with a slow metabolism.  The estimates vary, but approximately 10 million Americans have this common medical condition. In fact, as many as 10% of women may have some degree of thyroid hormone deficiency. Hypothyroidism is more common than you would believe, and millions of people are currently hypothyroid and don't know it. For an overview of how thyroid hormone is produced and how its production is regulated, check out our thyroid hormone production page.

 

Causes of Hypothyroidism

 

There are two fairly common causes of hypothyroidism. The first is a result of previous (or currently ongoing) inflammation

of the thyroid gland, which leaves a large percentage of the cells of the thyroid damaged (or dead) and incapable of producing sufficient hormone. The most common cause of thyroid gland failure is called autoimmune thyroiditis (also called Hashimoto's thyroiditis), a form of thyroid inflammation caused by the patient's own immune system.

 

The second major cause is the broad category of "medical treatments." The treatment of many thyroid conditions warrants

surgical removal of a portion or all of the thyroid gland. If the total mass of thyroid producing cells left within the body are not enough to meet the needs of the body, the patient will develop hypothyroidism. Remember, this is often the goal of the surgery for thyroid cancer.

 

But at other times, the surgery will be to remove a worrisome nodule, leaving half of the thyroid in the neck undisturbed.

Sometimes, this remaining thyroid lobe and isthmus will produce enough hormone to meet the demands of the body. For other patients, however, it may become apparent years later that the remaining thyroid just can't quite keep up with demand.

 

Similarly, goiters and some other thyroid conditions can be treated with radioactive iodine therapy. The aim of the radioactive

iodine therapy (for benign conditions) is to kill a portion of the thyroid to prevent goiters from growing larger

or producing too much hormone (hyperthyroidism).

 

Occasionally, the result of radioactive iodine treatment will be that too many cells are damaged so the patient often becomes

hypothyroid within a year or two. However, this is usually greatly preferred over the original problem.  There are several other rare causes of hypothyroidism, one of them being a completely "normal" thyroid gland that is not making enough hormone because of a problem in the pituitary gland. If the pituitary does not produce enough thyroid stimulating hormone (TSH) then the thyroid simply does not have the "signal" to make hormone. So it doesn't.

 

 

Sources:  http://www.endocrineweb.com/hypol.html

 

Treatment of Hyperthyroidism

 

Hypothyroidism is usually quite easy to treat (for most people)! The easiest and most effective treatment is simply taking a thyroid hormone pill (Levothyroxine) once a day, preferably in the morning. This medication is a pure synthetic form of T4 which is made in a laboratory to be an exact replacement for the T4 that the human thyroid gland normally secretes. It comes in multiple strengths, which means that an appropriate dosage can almost always be found for each patient. The dosage should be re-evaluated and possibly adjusted monthly until the proper level is established. The dose should then be re-evaluated at least annually. If you are on this medication, make sure your physician knows it so he/she can check the levels at least yearly.  Note:   Just like we discussed above, however, this simple approach does not hold true for everybody. Occasionally the correct dosage is a bit difficult to pin-point and therefore you may need an exam and blood tests more frequently.  Also, some patients just don't do well on some thyroid medications and will be quite happy on another.  For these reasons you should not be shy in discussing with your doctor your blood hormone tests, symptoms, how you feel, and the type of medicine you are taking.  The goal is to make you feel better, make your body last longer, slow the risk of heart disease and osteoporosis...in addition to making your blood levels normal!  Sometimes that's easy, when its not, you need a physician who is willing to spend the time with you that you deserve while you explore different dosages other types of medications (or alternative diagnoses).

 

Some patients will notice a slight reduction in symptoms within 1 to 2 weeks, but the full metabolic response to thyroid hormone therapy is often delayed for a month or two before the patient feels completely normal. It is important that the correct amount of thyroid hormone is used. Not enough and the patient may have continued fatigue or some of the other symptoms of hypothyroidism. Too high a dose could cause symptoms of nervousness, palpitations or insomnia typical of hyperthyroidism. Some recent studies have suggested that too much thyroid hormone may cause increased calcium loss from bone increasing the patient's risk for osteoporosis.  For patients with heart conditions or diseases, an optimal thyroid dose is particularly important. Even a slight excess may increase the patient's risk for heart attack or worsen angina. Some physicians feel that more frequent dose checks and blood hormone levels are appropriate in these patients.

 

After about one month of treatment, hormone levels are measured in the blood to establish whether the dose of thyroid hormone which the patient is taking is appropriate. We don't want too much given or subtle symptoms of hyperthyroidism could ensue, and too little would not alleviate the symptoms completely. Often blood samples are also checked to see if there are antibodies against the thyroid, a sign of autoimmune thyroiditis. Remember, this is the most common cause of hypothyroidism. Once treatment for hypothyroidism has been started, it typically will continue for the patient's life. Therefore, it is of great importance that the diagnosis be firmly established and you have a good relationship with a physician you like and trust.

 

Synthetic T4 can be safely taken with most other medications.  Patients taking cholestyramine (a compound used to lower blood cholesterol) or certain medications for seizures should check with their physician about potential interactions. Women taking T4 who become pregnant should feel confident that the medication is exactly what their own thyroid gland would otherwise make. However, they should check with their physician since the T4 dose may have to be adjusted during pregnancy (usually more hormone is needed to meet the increased demands of the mother's new increased metabolism). There are other potential problems with other drugs including iron-containing vitamins. Once again, pregnant women (and all women and men for that matter) taking iron supplements should discuss this with your physician. There are three brand name Levothyroxine tablets now available. You may want to consult with your physician or pharmacist on the most cost effective brand since recent studies suggest that none is better than the other.

 

Sources:  http://www.endocrineweb.com/conditions/thyroid/hypothyroidism-too-little-thyroid-hormone-0

 

 

 

Hyperthyroidism