Thyroid Disease: Hyperthyroidism and Hypothyroidism

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Thyroid disease: what is it?
Hyperthyroidism: detection
Hyperthyroidism: treatment
Hypothyroidism: detection
Hypothyroidism: treatment

DRUGS
CONDITIONS

Thyroid disease: what is it?

Thyroid disease is one of the most common hormonal diseases found in our society today. The most prevalent thyroid gland disorders are hyperthyroidism, hypothyroidism, and thyroid nodules.

Hyperthyroidism means there is too much thyroid hormone, which causes your metabolism to speed up. In many ways it is as if the body is stuck in "overdrive." The heart rate increases, muscles can become weak, and hands can begin to shake with a tremor. Bowel movements can be more frequent, and many people feel a sense of agitation or anxiety.

Hypothyroidism means there is too little thyroid hormone. This lack of thyroid hormone makes most of the body's organs slow down their function. Some people remark that they feel "like an engine that is not running on all cylinders." In many ways the symptoms of an underactive thyroid are opposite to those of an overactive or "hyper" thyroid gland. The heart rate slows, muscles become slow and weak and often ache, bowels become constipated, and people feel less energetic.

A thyroid nodule is an enlarged area or lump of tissue. Thyroid nodules are surprisingly common; how common depends on how hard you look for them. The vast majority of thyroid lumps are benign (not cancerous).

What is the thyroid gland – what does it do?

The thyroid gland is just under the skin in the front of your neck, just below your Adam's apple, and can be felt with your fingers. The thyroid gland is important because it produces thyroid hormones, which are necessary for the normal function of virtually all organs in the body. The 2 most important thyroid hormones are thyroxine (T4) and triiodothyronine (T3). These hormones, along with thyroid stimulating hormone (TSH) can be easily measured by taking a blood sample.

The role of the pituitary gland

The pituitary gland makes TSH and releases it into the bloodstream. TSH travels to the thyroid and causes the thyroid to release the hormones T4 and T3. T4 and T3 then travel through the bloodstream and regulate the function of various organs and metabolic processes within in your body. Some T4 is converted to T3 after leaving the thyroid.

What about iodine?

Iodine, an element found in food and water, is essential for the thyroid gland to produce thyroid hormones. Iodine deficiency is a cause of hypothyroidism, but varies in prevalence depending on geographic regions. For example, in North America and Europe, iodine deficiency is extremely rare because iodine is routinely added to salt. However, for people living in underdeveloped countries this is not the case, so iodine deficiency becomes a threat.

Is thyroid disease hereditary?

If a close relative has either an overactive or an underactive thyroid, then you are at increased risk for developing thyroid disease. This is not something that should be worrisome, however, as most people who have relatives with thyroid disease will not develop thyroid disease themselves.

All material copyright MediResource Inc. 1996 – 2024. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/healthfeature/gethealthfeature/Thyroid-Disease-Hyperthyroidism-and-Hypothyroidism

Hyperthyroidism: detection

Although there are many causes of hyperthyroidism, three or four diseases account for the majority of cases. The most common by far is Graves' disease.

Graves' disease takes its name from the physician who first described the condition. In some countries the disease may be called Basedow's or Parry's disease. Graves' disease is thought to be caused by a disordered immune system that attacks the thyroid and causes it to become over-active. It is an example of an "autoimmune disorder" where the immune system gets "confused" and accidentally attacks one of our organs instead of doing its usual job of fighting off bacteria and viruses that cause infections.

Other common causes of hyperthyroidism include:

Graves' disease
silent thyroiditis
subacute thyroiditis
post-partum thyroiditis
toxic nodule
toxic multinodular gland
pituitary tumor
ovarian or testicular tumor
excessive ingestion of thyroid hormone (either in the form of thyroid supplements or thyroid tissue from animals)

Is hyperthyroidism hereditary?

If a close relative has either an over-active or an under-active thyroid, then you are at increased risk to develop thyroid disease.

Signs and symptoms of hyperthyroidism

The symptoms of an over-active thyroid can develop slowly and be missed or confused with other illnesses. If you think you have some of the symptoms listed here, see your physician. Excess thyroid hormone will speed up your metabolism – in many ways it is like the body is stuck in "overdrive". The heart rate increases, muscles can become weak and hands can begin to shake with a tremor. Bowel movements can be more frequent and many people feel a sense of agitation or anxiety. Warm rooms can become intolerable and sweating may occur with minimal or even no exertion. Shortness of breath may occur. Roommates may notice that people with hyperthyroidism keep turning down the heat when others find it too cold. The increase in metabolism often causes weight loss. Eyes may become prominent or bulging. Osteoporosis may occur. Women may find their menstrual periods become irregular or even stop completely. Breast enlargement may occur in men.

How is an over-active thyroid diagnosed?

Thyroid function can be measured easily with a simple blood test. Usually this means measuring a thyroid stimulating hormone level (TSH). When the TSH level is low the thyroid is generally over-active. Sometimes additional tests such as a T4 or a T3 blood level need to be done. Once an over-active thyroid has been identified, a radioactive iodine thyroid scan can be helpful to clarify the cause of the hyperthyroidism.

Hyperthyroidism: treatment

Medication Management

There are several treatments for hyperthyroidism, including therapies that decrease the symptoms and those that stop the over-activity of the thyroid. The exact treatment depends on the cause of the hyperthyroidism. Some causes of hyperthyroidism do not need treatment, as left alone Mother Nature will eventually fix the problem.

Beta-blockers

Beta-blocker medications such as propranolol can be used to lessen the symptoms of hyperthyroidism. Propranolol is generally a short-term medication that is stopped once the underlying cause of hyperthyroidism has been corrected. People who have a history of asthma should not take propranolol or any other beta-blocker.

Anti-thyroid medications, radioactive iodine and surgery

Therapies that decrease the activity of the thyroid include anti-thyroid medications, radioactive iodine, or surgical removal of part or all of the thyroid. Surgery was one of the first treatments for hyperthyroidism and is still used today in some situations.

Anti-thyroid medications and radioactive iodine are the more common treatments for hyperthyroidism. The decision to use either therapy depends on many factors, including:

the underlying cause of your hyperthyroidism
your age
what other medical conditions you might have
whether you are pregnant or breast-feeding
what country you live in
your own personal beliefs and wishes

Radioactive iodine is very effective in correcting an over-active thyroid and, in North America, it is the most common treatment for people suffering from hyperthyroidism due to Graves' disease. Radioactive iodine can be taken orally, is tasteless and painless, and does not require hospitalization. Any extra radioactive iodine not absorbed by the thyroid is promptly excreted by the kidneys. In many ways, it is similar to removing the thyroid without surgery. However, radioactive iodine can induce an under-active thyroid, causing patients to require lifelong replacement with thyroid hormone. For this reason, some people choose anti-thyroid medications.

Anti-thyroid medications include methimazole and propylthiouracil (PTU). They are similar in that they decrease the thyroid's ability to make thyroid hormone. These drugs do not treat the underlying cause of the thyroid disease but instead control the excessive production of thyroid hormone. Generally, they are prescribed for 12 to 18 months and then stopped so your physician can determine if the underlying immune attack on the thyroid has ceased.1 Unfortunately, hyperthyroidism remains in remission without drugs less than 40% of the time.

Anti-thyroid medications have a number of potential side effects. Two are important to be aware of. The first is a rash which occurs in about 7-12% of people. The rash goes away when the pills are stopped, but it generally means you have to choose another method of treating the hyperthyroidism. The other important side effect is "agranulocytosis" or a decrease in white blood cells. White blood cells are the body's main line of defense against infection. A decrease or loss of white blood cells means that the body will not be able to fight off infection and a severe infection can result. Fortunately, this is a rare complication that occurs in approximately 1 in 500 people. When it does occur, it is very serious and requires urgent medical attention.

Surgical treatment of Graves' disease is rarely called for today. An example of when this would be necessary would be to treat a pregnant woman who is allergic to anti-thyroid drugs.

Therapeutic options to correct hyperthyroidism:

radioactive iodine
anti-thyroid pills
surgery to remove part or all of the thyroid

Table 1: Potential side effects from treatments for hyperthyroidism
TREATMENT	SIDE EFFECTS
Radioactive iodine	· Under-active thyroid (hypothyroidism) requiring lifelong thyroid hormone replacement · Most people who are treated with radioactive iodine will eventually develop hypothyroidism · Temporarily sore thyroid gland
Anti-thyroid pills	· Rash, usually requiring stopping the drug · Agranulocytosis: low white blood cells leading to infection risk (one in five hundred risk)
Surgery	· Under-active thyroid (hypothyroidism) requiring lifelong thyroid hormone replacement · Damage to nerves controlling vocal chords · Damage to parathyroid glands (glands responsible for maintaining calcium in the blood) · Surgical risks (typically less than 1% with experienced surgeons)

Will iodine tablets, kelp or seaweed supplements help?

Iodine often makes hyperthyroidism worse. As iodine is necessary for the body to make thyroid hormone, adding additional iodine to your diet may be like throwing gasoline on a smoldering fire. It is important to discuss any home remedies or health food supplements for the thyroid with your doctor prior to taking them.

What if I'm pregnant or planning to get pregnant?

Pregnant women should not take radioactive iodine as this could affect the thyroid of an unborn baby. Anti-thyroid drugs can be taken during pregnancy and surgery is sometimes recommended.

The timing of future pregnancies will affect the choice of therapy for hyperthyroidism. If radioactive iodine has been used, most physicians will recommend not becoming pregnant for 6-12 months. Whatever therapy you choose, the ideal situation is to be drug free, with normal levels of thyroid hormone in your body before getting pregnant.

Hypothyroidism: detection

What causes hypothyroidism?

The most common cause of thyroid hormone deficiency is called Hashimoto's thyroiditis. Hashimoto was the first physician to describe the disorder and hence his name has been applied to this autoimmune disorder. Autoimmune disorders are diseases where the immune system gets "confused" and accidentally attacks one of the body's organs instead of fighting off foreign invaders such as bacteria and viruses that cause pneumonia or other infections. The same body system begins to attack and destroy cells in the thyroid gland, resulting in the failure of the body to produce the necessary amount of thyroid hormone.

Other common causes of hypothyroidism include:

cases arising after surgery or radioactive iodine therapy for Grave's disease
silent thyroiditis
subacute thyroiditis
postpartum thyroiditis radioactive iodine use
drug-induced
inherited
pituitary gland dysfunction
hormone resistance
iodine deficiency

Hypothyroidism due to silent thyroiditis, subacute thyroiditis, or postpartum thyroiditis usually is self-limited and naturally corrects itself within a number of months.

Iodine deficiency is an extremely rare cause of hypothyroidism in people living in North America or Europe, but can still be seen in people living in underdeveloped countries where salt is not routinely supplemented with iodine.

Signs and symptoms

The symptoms of an underactive thyroid can develop slowly and be missed or confused with other illnesses. The heart rate slows, muscles become slow and weak, and often ache, bowels become constipated and body energy levels drops. Cold or drafty rooms become intolerable and people may wear multiple layers of clothing and turn up the heat in their homes in an attempt to keep warm. The slowing of the metabolism will cause an increase in body weight. This weight increase can often occur despite eating less and exercising. Fluid retention occurs and puffiness or edema can be found at the ankles or around the eyes. Hair may begin to fall out and skin will become dry. A depressed mood, poor sleep, and decreased libido (sex drive) may occur. Women may notice their periods become irregular, heavier, or longer. Anemia (low blood count) may develop. In severe cases the voice can become hoarse, or progressive drowsiness to the point of unconsciousness may develop.

How is an underactive thyroid diagnosed?

Thyroid function can be measured easily with a simple blood test. Usually this means measuring a TSH level. When the TSH level is high, the thyroid is generally underactive. Sometimes, additional tests such as a T4 or a T3 blood level will need to be done. Once diagnosed, it is important to determine the cause of the hypothyroidism.

Hypothyroidism: treatment

Medication Management

Thyroid hormone replacement is the standard treatment for thyroid hormone deficiency. There are many preparations available with new formulations under development. All thyroid hormone preparations contain either T4 (thyroxine), T3 (triiodothyronine) or a combination of these two main thyroid hormones. Historically, the first replacement therapies available were preparations made of extracts from animal thyroids such as dried thyroid or thyroglobulin, and they worked quite well. However, problems with standardizing doses and maintaining uniform replacement lead to the use of the purified synthetic hormones alone.

T3 therapy requires multiple doses per day and can cause fluctuations in hormone levels, which many people feel. T4 therapy provides stable levels of both T4 and T3 in the blood and is the most common method of replacing thyroid hormone. Occasionally, a combination of T4 and T3 is used for treatment.

The best method of thyroid hormone replacement for you may depend on your own clinical situation. Occasionally, some experimentation with replacement methods is required to "reproduce" the natural levels of thyroid hormone that existed prior to the development of hypothyroidism. The best way to begin is with T4 replacement. It is the least complex way to replace lost thyroid hormones and with the correct dosage most patients feel completely normal on it. In addition to how you feel your doctor may assess your response by measuring your thyroid stimulating hormone (TSH).

Table 1: Common preparations and brand names of thyroid hormone replacement
HORMONE	BRAND NAME
T4 (thyroxine)	Synthroid® Eltroxin®
T3 (triiodothyronine) pills	Cytomel®
T4, T3 combinations	T4 taken with Cytomel®
Desiccated thyroid	Thyroid Hormone®

Table 2: Methods of thyroid hormone replacement and advantages or disadvantages related to the different hormone preparations
HORMONE	ADVANTAGES	DISADVANTAGES
T4 (Thyroxine) therapy	Once a day dosing Uniform blood levels Easily obtained	May not supply sufficient T3 in some cases
T3 (Triiodothyronine) therapy	T3 levels are ample	May not supply sufficient T4 Blood levels fluctuate4
Combination T4 and T3 therapy	Attempts to mimic normal blood levels4	Additional cost May not be required in most patients
Desiccated thyroid	"Natural" but from animal source	Uniform replacement can be problematic Variable T3 levels over the day

What about thyroid hormone blocks?

Rare syndromes exist where thyroid hormone levels are normal but the hormone is "blocked" from having its full effect in the body. These are caused by abnormal receptors to the thyroid hormone. An endocrinologist can determine whether you have a block or "resistance" to thyroid hormone. Excessive replacement of thyroid hormone can have potential adverse consequences such as damaging your bones or heart. Consequently, taking high doses of thyroid hormone should be discussed with your physician before any course of treatment is started.

Will iodine tablets, kelp or seaweed supplements help?

Iodine supplementation is used to treat hypothyroidism caused by iodine deficiency. Because there is iodine supplementation in salt in North America and Europe, iodine deficiency is extremely rare in these regions. Occasionally, excessive iodine can cause a decrease in thyroid function, so it is important to discuss any home remedies or health food supplements for the thyroid with your doctor prior to taking them.

What about pregnancy and hypothyroidism?

Normal thyroid hormone levels are recommended prior to and during pregnancy. Thyroid hormones are natural hormones and do not hurt the developing baby. However, it is important to ensure that the dose of thyroid hormone you are on is correct throughout the pregnancy as often a dose adjustment is required as pregnancy progresses. The best test to follow during pregnancy is the TSH blood test. Your physician will be able to help you with the timing of the testing and any adjustments in hormone that may be required.