Wisdom Wednesday: The Thyroid Profile

The TSH (thyroid stimulating hormone) is the gold standard for evaluating thyroid health. TSH is a pituitary hormone that directs the thyroid to make T4. The normal lab range is 0.4 – 4.5 ulU/L. However, the functional range is much narrower from 1-2 ulU/L. This functional range has been recommended by the American Board of Endocrinology since 2003, but has been ignored by most physicians.

As a minimum, I also recommend running a T3 and T4. Approximately 97% of the thyroid hormone produced by the thyroid gland is in the form of T4. This is the inactive, stable form that circulates in your blood stream. It is called T4 because it is a cholesterol ring with four molecules of iodine attached to it.

When the body’s basic metabolism requires stimulation, the liver removes one molecule of iodine from T4 making T3, the active form of thyroid hormone. This is under the direction of the adrenal glands which take their orders from the hypothalamus and pituitary (home of TSH).

Most thyroid issues are related to poor conversion of T4 to T3, so including these tests when evaluating the thyroid is a must.

Under high levels of stress, the liver can remove the wrong iodine molecule creating ‘reverse T3’. It is indistinguishable from normal T3 and must be measured directly. This is a common occurrence in American Indians and those of Irish decent. Reverse T3 does not have any metabolic function and appears to be a safety valve when stress levels are so high that excess T3 might be released from the liver. Again, this test is seldom run in traditional medical practices.

Wisdom Wednesday: Hashimoto’s Thyroiditis

Hashimoto’s thyroiditis is a condition in which your immune system attacks your thyroid. The thyroid gland is part of your endocrine system, which produces hormones that coordinate many of your body’s activities.

The thyroid is responsible for general metabolism. It facilitates the Krebs’s Citric Acid Cycle to provide energy for every cell in the body. Thyroid hormone is what gets you out of bed in the morning. During the day, various stressors stimulate the adrenals to produce additional hormones to further facilitate general metabolism.

The inflammation from Hashimoto’s thyroiditis often leads to an underactive thyroid gland (hypothyroidism).

Hashimoto’s disease is the most common cause of hypothyroidism in the United States. It primarily affects middle-aged women but also can occur in men and women of any age and in children. It is estimated that one in three cases of hypothyroidism is caused by Hashimoto’s disease, but I feel that statistic is low and it’s much closer to 50% of cases clinically in my office.

The signs and symptoms of hypothyroidism include fatigue, increased sensitivity to cold, constipation, pale, dry skin, puffy face, hoarse voice, unexplained weight gain, hair loss (especially the lateral third of the eyebrows) and depression. The two male patients currently in my practice with Hashimoto’s thyroiditis are both underweight. One has none of the common symptoms but does suffer from seizures and apnea, both associated with this disease. The other exhibits constipation as the only common symptom.

The low diagnostic rate is due to a lack of testing. The TSH (thyroid stimulating hormone) is the “gold standard” for diagnosing a thyroid problem. However, the TSH is a pituitary hormone that stimulates the thyroid and not really a thyroid hormone. It works through negative feedback. The hypothalamus monitors T3 and T4 production (the real thyroid hormones). When the level of T3 or T4 drops, the hypothalamus tells the pituitary gland to release more TSH, this stimulates the thyroid to make more hormone. As the thyroid hormone levels rise, the hypothalamus tells the pituitary to make less TSH. So TSH regulates thyroid hormone production and is a useful tool in looking for thyroid problems.

However, often the TSH is well within medical norms and a significant thyroid issue exists. In part this is due to the wide range of normal set by the laboratory industry. The norm is 0.4 to 4.5 uIU/mL. The American College of Endocrinology established a normal range of 1.0 to 2.0 uIU/mL in 2002 that has been largely ignored.

Wisdom Wednesday: Thyroid Disease

The American College of Endocrinology (ACE) is the educational and scientific arm of the American Association of Clinical Endocrinologists (AACE). ACE has begun an awareness program designed to increase dialogue between patients, their physicians, and pharmacists. This program is available to the public at www.thyroidawareness.com. If you want more information after reading this blog, please visit their web site.

AACE president Dr. R. Mack Harrell, who is a thyroid specialist, stated “Thyroid hormone is the leading prescription drug in our country, and there are a lot of misconceptions about what thyroid disease is and what the thyroid does.”

The thyroid manufactures thyroid hormone from cholesterol and four molecules of iodine. This product is called T4. T4 is then released into the blood stream where it does nothing. T4 is the stable form of thyroid hormone. When your metabolism needs a boost, one of the iodine molecules is stripped from T4 creating T3. This is the active form of the hormone and stimulates general metabolism. Your ability to get out of bed in the morning and start your day is dependent on T3.

Eighty percent of T3 is created in the liver; the remaining twenty percent is formed in the kidneys. However, T4 to T3 conversion is under the control of the adrenals. Healthy thyroid hormone levels are dependent on the thyroid, liver, kidneys and adrenals. The function of all these glands and organs is controlled by the pituitary gland.

Standard Treatment for Underactive Thyroid Gland Still Best

A expert panel reviewing treatments for hypothyroidism has concluded that the drug levothyroxine (L-T4) should remain the standard of care.

The updated guidelines from the American Thyroid Association were published recently in the journal Thyroid.

The thyroid gland produces hormones that control the way every cell in the body uses energy. For example, thyroid hormones control how fast you burn calories and how fast your heart beats. If the thyroid gland produces too little thyroid hormone to control these activities the condition is called hypothyroidism.

A task force convened by the thyroid association reviewed available medical literature and found no evidence that other types of thyroid hormone replacements are better than L-T4, which has long been the standard of care for patients with hypothyroidism. Brand names for L-T4 include Synthroid and Levoxyl.

However, while L-T4 is effective in most patients, some do not regain ideal health when taking L-T4 alone, the authors noted.

The guidelines “provide useful, up-to-date information on why to treat, including subclinical disease, who to treat, and how to treat hypothyroidism,” Dr. Hossein Gharib, president of the thyroid association, said in a journal news release.

“Information is evidence-based and recommendations are graded. I think they will be used extensively by all clinical endocrinologists, especially by our members,” added Gharib, a professor of medicine at the Mayo Clinic College of Medicine in Rochester, Minn.