Thyroid Problems

Thyroid Problems Overview

The thyroid gland is located on the front part of the neck below the thyroid cartilage (Adam's apple). The gland produces thyroid hormones, which regulate body metabolism. Thyroid hormones are important in regulating body energy, the body's use of other hormones and vitamins, and the growth and maturation of body tissues.

Diseases of the thyroid gland can result in either production of too much (hyperthyroidism) or too little (hypothyroidism) hormone.
Production of thyroid hormones: The process of hormone synthesis begins in a part of the brain called the hypothalamus. The hypothalamus releases thyrotropin-releasing hormone (TRH). The TRH travels through the bloodstream to the pituitary gland, also in the brain. In response, the pituitary gland then releases thyroid-stimulating hormone (TSH) into the blood. The TSH then stimulates the thyroid to produce the two main thyroid hormones, L-thyroxine (T4) and triiodothyronine (T3). The thyroid gland also needs adequate amounts of dietary iodine to be able to produce T4 and T3.
Regulation of thyroid hormone production: To prevent the overproduction or underproduction of thyroid hormones, the pituitary gland can sense how much hormone is in the blood and adjust the production of hormones accordingly. For example, when there is too much thyroid hormone in the blood, the TRH does not work effectively to stimulate the pituitary gland. In addition, too much thyroid hormone will prevent the release of TSH from the pituitary gland. The sum effect of this is to decrease the amount of TSH released from the pituitary gland, resulting in less production of thyroid hormones in the thyroid gland. This then works to restore the amount of thyroid hormone in the blood to normal. Defects in these regulatory pathways may result in hypothyroidism or hyperthyroidism.
Hypothyroidism in pregnancy

Newly diagnosed hypothyroidism in pregnancy is rare because most women with untreated hypothyroidism have ovulatory problems, which make it difficult for them to conceive.

It is a difficult new diagnosis to make. Many of the symptoms of hypothyroidism (fatigue, poor attention, weight gain, numbness, and tingling of the hands or feet) are also prominent symptoms of a normal pregnancy.

Undiagnosed hypothyroidism during pregnancy increases the chance of stillbirth or growth retardation of the fetus. It also increases the chance that the mother may experience complications such as anemia, eclampsia, and placental abruption.

Probably the largest group of women who will have hypothyroidism during pregnancy are those who are currently on thyroid hormone replacement. The ideal thyroxine replacement dose during pregnancy may rise by 25-50% during pregnancy. It is important to have regular checks of T4 and TSH during pregnancy to make sure you are at the correct medication dose.
Hyperthyroidism in pregnancy

Newly diagnosed hyperthyroidism occurs in about 1 in 2,000 pregnancies. Graves disease accounts for 95% of hyperthyroidism newly diagnosed during pregnancy.

Like hypothyroidism, many symptoms of mild hyperthyroidism mimic those of normal pregnancy. However, anyone experiencing symptoms such as significant weight loss, vomiting, increased blood pressure, or persistently fast heart rate should have blood tests to look for hyperthyroidism.

Untreated hyperthyroidism does cause fetal and maternal complications similar to untreated hypothyroidism.


Treatment of hyperthyroidism during pregnancy is primarily medical. Propylthiouracil or methimazole are usual first-line agents to block the synthesis of thyroid hormone. They appear to be equally effective and have the same rate of side effects. The rate of side effects of each medication is not increased in pregnancy.

Iodine will cross the placenta, so its use in either a thyroid scan or in treatment with radioactive iodine is prohibited in pregnancy.

One positive note for women with hyperthyroidism is that those with Graves disease or Hashimoto thyroiditis may have improvement in their symptoms during pregnancy.

Postpartum thyroid disease
Some women may have thyroiditis that usually occurs within 3-6 months after birth. It also may occur after miscarriage. The classic clinical picture is a woman who will first have symptoms of hyperthyroidism, followed by hypothyroidism, culminating in normal thyroid function.

Women with insulin-dependent diabetes have a 25% risk of developing postpartum thyroid dysfunction.

Consult your doctor if you have symptoms of hypothyroidism or hyperthyroidism after pregnancy or miscarriage.


Thyroid Problems Causes

Hypothyroidism

Loss of tissue: Treatment of hyperthyroidism by radioactive destruction of thyroid tissue or surgical removal of thyroid tissue can result in hypothyroidism.

Antithyroid antibodies: These may be present in people who have diabetes, lupus, rheumatoid arthritis, chronic hepatitis, or Sjögren syndrome. These antibodies may cause decreased production of thyroid hormones.

Congenital: Hypothyroidism can be present from birth. This is commonly discovered early with nationwide newborn screening for this disease.

Defects in the production of thyroid hormone: Hashimoto thyroiditis occurs when there are defects in the production of thyroid hormone, resulting in an increased amount of TSH. The increased TSH results in a goiter (enlargement of the thyroid gland itself that can be seen as an obvious swelling in the front of the neck).

Medications: Some medications, particularly lithium, may cause a drug-induced hypothyroidism.

Hyperthyroidism

Graves disease: This thyroid condition results from abnormal stimulation of the thyroid gland by a material in the blood termed the long-acting thyroid stimulator (LATS). LATS overstimulates the thyroid causing a goiter. It also causes Graves eye disease, including a "bug-eyed" look and "frightened stare." This can progress to severe eye pain or eye muscle weakness. It also causes raised, thickened skin over the shins or tops of the feet.

Toxic multinodular goiter: This occurs when part of the thyroid gland produces thyroid hormones all by itself, without regard to TSH stimulation. It usually occurs in people with a long-standing goiter—usually in the elderly. Toxic multinodular goiter is different from Graves disease because of the general lack of eye complications and less severe signs of hyperthyroidism.

Thyroiditis: This inflammatory disorder of the thyroid gland includes such conditions as de Quervain thyroiditis or Hashimoto thyroiditis. In these conditions, you may have periods of increased thyroid hormone release due to the inflammation, causing a hyperthyroid state. As thyroid failure occurs due to the inflammatory response, hypothyroidism may occur.

Pituitary adenoma: This tumor of the pituitary gland causes independent TSH production leading to overstimulation of the thyroid gland.

Drug-induced hyperthyroidism: This is most commonly caused by a heart medication called amiodarone. It may be prevented by monitoring this possible side effect and weighing it against the benefits of using the heart medication.


Thyroid Problems Symptoms

Hypothyroidism

Infants

Constipation

Poor feeding

Jaundice (yellow discoloration of the skin and eyes)

Excessive tiredness
Children

Similar to adult symptoms

Poor school performance
Adults

Early symptoms

Easy fatigue, exhaustion

Poor tolerance to cold temperatures

Constipation

Carpal tunnel syndrome (pain at the wrists and numbness of the hands)

Later symptoms

Poor appetite

Weight increase

Dry skin

Hair falls out

Intellectual ability worsens

Deeper, hoarse voice

Puffiness around the eyes

Depression
Hyperthyroidism

Children

Similar to adult symptoms

Declining school performance

Behavior problems
Adults

Insomnia

Hand tremors

Nervousness

Feeling excessively hot in normal or cold temperatures

Frequent bowel movements

Losing weight despite normal or increased appetite

Excessive sweating

Menstrual period becomes scant, or ceases altogether

Joint pains

Difficulty concentrating

Eyes seem to be enlarging
Elderly

Worsening of angina (chest pain) in person with heart disease

Worsening of shortness of breath in person with heart failure

Muscle weakness, especially in the shoulders and thighs


When to Seek Medical Care

The signs and symptoms of hypothyroidism and hyperthyroidism typically develop slowly over a period of weeks to months. If you have prolonged symptoms or signs of either condition, call your doctor to be evaluated.

Untreated hypothyroidism may have severe effects on the brain as well as cause intestinal obstruction and inability of the heart to beat effectively. An infection, exposure to cold, trauma, and certain medications may often cause a worsening of hypothyroidism.
Seek immediate attention at a hospital's emergency department if you have these signs and symptoms associated with thyroid problems.

Shortness of breath

Abdominal pain

Vomiting

Confusion

Coma
Severe hyperthyroidism, called thyrotoxic crisis, may be life threatening because of the effects it has on the heart and brain. It often occurs in people who are untreated or are receiving inadequate treatment for thyroid problems. A severe infection can also cause a thyrotoxic crisis.

Seek immediate attention at a hospital's emergency department if you have these signs and symptoms associated with thyroid problems.

Chest pain

Shortness of breath

Abdominal pain

Vomiting

Extreme agitation or irritability

Disorientation (person has no knowledge of the date or location)

Coma


Exams and Tests

The medical history and physical exam are important parts of the evaluation for thyroid problems. The doctor will focus on eye, skin, cardiac, and neurologic findings.
Blood tests

Thyroid-stimulating hormone (TSH): In most cases, this is the single most useful lab test in diagnosing thyroid disease. When there is an excess of thyroid hormone in the blood, as in hyperthyroidism, the TSH is low. When there is too little thyroid hormone, as in hypothyroidism, the TSH is high.

L-thyroxine (T4): T4 is one of the thyroid hormones. High T4 may indicate hyperthyroidism. Low T4 may indicate hypothyroidism.

Triiodothyronine (T3): T3 is another one of the thyroid hormones. High T3 may indicate hyperthyroidism. Low T3 may indicate hypothyroidism.

TSH receptor antibody: This antibody is present in Graves disease.

Antithyroid antibody: This antibody is present in Hashimoto disease.

Thyroid scan: For this test, a small amount of radioactive iodine is given into the blood, and then an x-ray image of the thyroid is taken. Increased uptake of the radioactive material in the thyroid gland indicates hyperthyroidism, while decreased uptake is present in hypothyroidism. This test should not be done on pregnant women.

Thyroid ultrasound: This exam helps to differentiate between different types of nodules of the thyroid gland.

Fine-needle aspiration: For this test, a small needle is inserted into the thyroid gland in order to get a sample of thyroid tissue, usually from a nodule. The tissue is then observed under a microscope to look for any signs of cancer.


Thyroid Problems Treatment

Medications

Medications for hyperthyroidism
Beta-blockers: This class of medications works by blocking many of the body’s responses to hyperthyroidism. It decreases tremor, nervousness, and agitation. It also reduces the fast heart rate. It is given as tablets to the person with mild to moderate symptoms, and as an IV preparation to the person with the severe form of hyperthyroidism (thyrotoxic crisis).
Propylthiouracil: This antithyroid drug works by blocking thyroid hormone synthesis. It takes about a week after starting the medication for full therapeutic effect. Common mild side effects include rash, itching, and mild fever. More rare, serious side effects include a decrease in white blood cell count, which can decrease the ability to fight off infection. Therefore, a high fever should prompt a call to the doctor.
Methimazole (Tapazole): This antithyroid drug also works by blocking thyroid hormone synthesis. It may take slightly longer than propylthiouracil to achieve full effect. It has similar side effects as propylthiouracil and may also cause a decreased white blood cell count.
Iodide (Lugol’s solution, Strong iodine): This medication works by inhibiting the release of thyroid hormone from the overfunctioning thyroid gland. It must be used in conjunction with an antithyroid drug because the iodine can be used to increase the amount of thyroid hormone and worsen the hyperthyroidism. Common side effects include nausea and a metallic taste in the mouth.

Medications for hypothyroidism
L-thyroxine: This medication is the mainstay of thyroid hormone replacement therapy in hypothyroidism. This is a synthetic form of thyroxine. The body tissues convert it to the active product L-triiodothyronine. Side effects are rare, and it has an excellent safety record.
L-triiodothyronine: This is rarely used alone as thyroid hormone replacement, because it has less uniform potency than L-thyroxine. Its use can cause rapid increases in L-triiodothyronine concentration, which can be dangerous in the elderly and in people with cardiac disease. It may be used in combination with L-thyroxine for people who have poor symptomatic relief with L-thyroxine alone.


Surgery

Surgery for hyperthyroidism may involve removal of much of the thyroid tissue, leaving some intact to continue to produce thyroid hormone. Risks in this procedure include damage to nerves that control the vocal cords, damage to the parathyroid glands, which lie just behind the thyroid gland, and bleeding causing breathing problems. Hypothyroidism may also occur, but occurs less frequently than in radioactive iodine treatment. Persistent hyperthyroidism may also occur. If so, the entire thyroid gland is removed. In general, in the hands of an experienced surgeon, this is considered an effective and relatively safe procedure.


Next Steps

Follow-up

Anyone diagnosed with Graves disease should stop smoking immediately because smoking increases the risk of progression to Graves eye disease.


Follow the medication schedule prescribed by your doctor. In addition, ask what side effects the medications may cause. Also discuss with your doctor the kinds of symptoms that would prompt a call to the doctor or a visit to the emergency department.


Prevention

There is no known way to prevent hyperthyroidism or hypothyroidism.

Outlook

Most people with either hypothyroidism or hyperthyroidism, with proper diagnosis and treatment, can control their condition with no long-term effects. However, those with undiagnosed disease may progress to coma or thyrotoxic crisis, with death rates approaching 50%.

Graves eye disease has been treated with corticosteroid medication, radiotherapy, and surgery with varying success.