Dr. MJ Bazos MD, Patient Handout

The influence of the thyroid gland is both far-reaching and critical to normal body function. It affects heart rate, cholesterol level, body weight, energy level, muscle strength, skin condition, vision, menstrual regularity, mental state and a host of other conditions. Despite its pervasive influence, however, the thyroid gland and its disorders are still not widely understood among the general public.

The thyroid is a butterfly shaped gland which wraps around the front part of the windpipe just below the Adam's apple. It produces hormones that regulate the body's metabolism and organ function. Thyroid hormone influences essentially every organ, every tissue and every cell in the body.

The most common thyroid disorder is an underactive thyroid, or hypothyroidism. This results when the thyroid fails to produce enough hormone. Less frequently, an overactive thyroid condition, or hyperthyroidism, occurs when the thyroid produces more thyroid hormone than is needed. If properly treated, patients with thyroid disorders lead normal, active lives. When left untreated, however, thyroid disorders can affect the patient's cardiovascular system, reproductive system and other major organs.

How the Thyroid Functions

The thyroid gland operates as part of a feedback mechanism involving the hypothalamus and the pituitary gland. First, the hypothalamus sends a signal to the pituitary gland through a hormone called TRH (thyrotropin releasing hormone). When the pituitary gland receives this signal, it releases TSH (thyroid stimulating hormone) to the thyroid gland. Upon receiving TSH, the thyroid responds by releasing two of its own hormones, T4 and T3, which then enter the bloodstream and affect the metabolism of the heart, liver, muscle and other organs. T4 is the main hormone released by the thyroid. T3 is made in the tissue after T4 to T3 conversion. Finally, he pituitary "monitors" the level of thyroid hormone in the blood and increases or decreases the amount of TSH released, which then changes the amount of thyroid hormone in the blood.


The most common type of thyroid disorder, hypothyroidism (underactive thyroid) occurs when the thyroid gland fails to produce enough thyroid hormone -- hormones which influence essentially every organ, every tissue and every cell in the body. Hypothyroidism affects an estimated 11 million Americans, particularly women and the elderly.

In the U.S., the most common type of hypothyroidism is Hashimoto's disease, a condition caused when the immune system produces killer lymphocytes that destroy the thyroid. As the damaged thyroid gland produces less thyroid hormones, the pituitary gland secretes more thyroid-stimulating hormone (TSH) to encourage the thyroid to work harder. This increased demand on the thyroid may cause it to enlarge, resulting in what is commonly known as a goiter. Antibodies are produced that serve as a diagnostic test for Autoimmune Disease.

Signs and Symptoms

In the case of mild thyroid failure, patients often do not show obvious symptoms and thus may not even be aware of their condition. Left untreated, however, mild thyroid failure can progress to where symptoms begin to surface. Some of the signs and symptoms of hypothyroidism include:

Symptoms of Hypothyroid

Detection and Diagnosis

Hypothyroidism may be difficult to detect because its often vague signs and symptoms are easily confused with other conditions, such as the natural aging process, menopause or stress. Many patients remain undiagnosed and untreated for years due to their lack of awareness of hypothyroidism and its signs and symptoms.

Fortunately, even mild hypothyroidism can be detected by a sensitive TSH (thyroid stimulating hormone) test, which enables physicians to identify thyroid disorders much earlier than with previous tests. By detecting hypothyroidism in its early stages, physicians may administer treatment and prevent the onset of symptoms.


The goal for treating hypothyroidism is to restore normal blood levels of thyroid hormone by replacing missing hormone. The treatment of choice for hypothyroidism involves supplementing the body's naturally produced hormone with a synthetic hormone tablet, levothyroxine sodium, which is generally taken for life.

After levothyroxine sodium therapy has been prescribed, periodic TSH tests are needed to monitor thyroid hormone levels. Because patient dosage requirements may change over time according to age, body weight, cardiovascular status and other diseases or medications, it is essential to monitor patients' medication needs on a regular basis. Monitoring precise dosages effectively prevents recurrence of symptoms of hypothyroidism and prevents over-replacement, which can in turn lead to hyperthyroidism.

Hypothyroid patients should not switch to different brands of levothyroxine sodium without consulting a physician. Both the American Association of Clinical Endocrinologists (AACE) and the American Thyroid Association (ATA) have released clinical guidelines recommending that patients be retested and their dosages adjusted accordingly if they switch levothyroxine sodium products. AACE further advocates that physicians treat patients with the same brand of levothyroxine throughout their lifetime. There is no place for Armour Thyroid in therapy. Beware of pseudoscientific non- diseases such as Wilson's.


Hyperthyroidism, a less common thyroid disorder, occurs when the thyroid gland becomes overactive and produces too much thyroid hormone. It affects approximately one to two million Americans, and is more prevalent among women, particularly those in their 30s and 40s. The most common form of this disorder is Graves' disease, the illness that affected Olympic athlete Gail Devers and former First Lady Barbara Bush. The cause of Graves' disease is unknown.

Signs and Symptoms

The spectrum of possible signs and symptoms resulting from an overactive thyroid includes:

Symptoms of Hyperthyroid


Treatment of an overactive thyroid may be complex and requires a long-term care plan. Once diagnosis is confirmed, treatment involves reducing the amount of thyroid hormone produced by the gland. Treatment methods for hyperthyroidism include antithyroid drug therapy, which blocks thyroid hormone production; radioactive iodine treatment, in which the overactive thyroid is disabled and reduced in size; and thyroid surgery to remove part or all of the gland, which is usually used to treat very young patients with Graves' disease and older patients with diseased thyroid glands.

Radioactive iodine therapy is currently the treatment of choice in most cases in the United States. Patients are given a dose of Radioactive iodine that essentially "shuts down" thyroid hormone production. Normal hormone levels must often be restored through levothyroxine sodium tablets. These patients require careful lifetime management to ensure they are receiving the proper dosage of thyroid medication.

Surgery is a good option for some, especially if a nodule is present that is suspicious of FNA.


A Johns Hopkins University study published in the Journal of the American Medical Association proposes routine testing for mild thyroid failure among the general adult population. It concluded that periodic screening men and women 35 and older at regular intervals is as cost-effective a health strategy as screening for more common medical conditions such as high cholesterol or high blood pressure. In making this determination, the study involved the use of the test widely considered to provide the most accurate measure of thyroid gland activity the sensitive thyroid-stimulating hormone (TSH) test.

In the past, doctors were unable to detect thyroid disorder until a patient's symptoms were fairly advanced. With the sensitive TSH test, however, physicians are able to diagnose thyroid disorders at an earlier stage in many cases, even before patients begin to experience symptoms. TSH tests, due to their high degree of sensitivity, enable physicians to detect even slight abnormalities in thyroid function. Early detection and treatment of thyroid disorder allows physicians to prevent the onset of disease symptoms and curb potential organ effects for their patients.

Prior to the introduction of the TSH test, the standard blood tests or thyroid disorders measured the levels of thyroid hormones (T4 and T3) in the blood. Research showed, however, that these hormone levels could be within the normal range even when the thyroid was not functioning normally. The TSH test offers a marked advance by identifying the amount of thyroid-stimulating hormone produced by the pituitary gland, the organ that signals the thyroid gland to produce more or less T4 and T3 based on the body's need. In effect, the TSH test takes advantage of the "wisdom" of the pituitary gland, the organ that first recognizes thyroid dysfunction, and therefore provide a more exact measure of thyroid failure.

A TSH test is administered by drawing a small blood sample and sending it to a laboratory for analysis. The laboratory will read the level of TSH, and based on a reported normal value range, it will determine whether the level is below normal (hyperthyroid), above normal (hypothyroid) or within the normal range (euthyroid).

People who believe they may have a thyroid disorder should ask their primary care physician or an endocrinologist to have their TSH level assessed. In support of this precise tool for measuring thyroid activity, the American Association of Clinical Endocrinologists released clinical practice guidelines strongly advocating the use of TSH tests for diagnosing thyroid conditions.

Beyond disease diagnosis, TSH tests play a critical role in helping physicians manage thyroid disorders. In this capacity, TSH tests are used to determine precise medication treatment dosages for patients with hypothyroidism and hyperthyroidism, as well as to monitor changes in dosage requirements over time.