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THE THYROID GLAND: LOW FUNCTIONING AND HIGH FUNCTIONING, HYPOTHYROIDISM AND HYPERTHYROIDISM.

By Dr. Keith E. Lewis
May 22, 2008


The thyroid gland is a butterfly-shaped organ located in the neck. Its main function is to produce thyroid hormone. Thyroid hormones control metabolic rate. It is the "master metabolizer" gland.

The thyroid gland uses iodine mostly found in food such as seafood, bread, and salt to produce thyroid hormones. The two most important thyroid hormones are thyroxin (T4) and triiodothyronin (T3). While a small amount of T3 is actually made in the thyroid gland, most of it is converted in the tissues from T4 released from the thyroid gland into the blood. T3, however, is the active hormone that affects the metabolism in cells. T3 is much more powerful than T4 in terms of the affect on metabolism.  

Excess amounts of thyroid hormone, hyperthyroidism, overly stimulates the body.  Results are increased heart rate, anxiety, and weight loss, while a lack of thyroid hormone, hypothyroidism, can cause depression, sluggishness, weight gain, heart failure, thinning of the hair, brittling of the nails, and no energy. Hyperthyroidism is rare. Only about 1% of the population experiences this. While mild subclinical hypothyroidism may be much more common than most people think, clinical hypothyroidism, is common, experts believe 80% of our population experiences this to some degree.

The most common cause of overt hypothyroidism in United States is an autoimmune disorder known as Hashimoto's thyroiditis. This condition is basically characterized by an overactive immune system and in that response floods the thyroid gland with white blood cells and they are basically attacking the body itself.  Hashimoto is more common in women than in men and there is a genetic component to the disease.

Worldwide, however, lack of dietary iodine can cause hypothyroidism. Iodine is necessary for the synthesis of thyroid hormone. At least most table salt is iodized.  Iodine typically has not been considered to be a huge problem. Other than iodine, thyroid function can be affected by a number of other nutrients including zinc and selenium. Deficiencies in either of these have been shown to increase the risk of hypothyroidism.

Hypothyroidism is typically treated with supplemental thyroid hormones. These hormones typically are synthetic in nature. There are several different approaches to the treatment of hypothyroidism. One of course, as I said, being synthetic hormones and naturally desiccated thyroid hormone from animals.  

A combination of drugs provides fixed ratios of T3 and T4. The choice of which form of thyroid hormone to use is an individual decision to be made on the basis of blood test and effectiveness of the therapy. The majority of thyroid hormone is produced by the thyroid gland and produces T4. T4 only slightly affects body's metabolic rate. The most active hormone is T3. To supply the necessary T3, the liver and other tissues convert T4 to T3. T4 and T3 are essential for regulating metabolic processes throughout the body including maintaining the basal metabolic rate, making more glucose available to meet the elevated metabolic demand, stimulating new protein synthesis, increasing metabolism of lipids, and conversion of cholesterol into bile acids, activating lipoprotein lipase, and increasing sensitivity of adipose tissue to hormones that stimulate the breakdown of fat, increasing cardiac output and blood flow, and increasing neural transmission. If untreated, chronic hypothyroidism can result in myxedema, a rare life-threatening condition, mental dysfunction, stupor, cardiovascular collapse, and coma can develop after worsening of chronic hypothyroidism. The patients may pass into a hypothalamic stupor, coma, and die. Again this is rare but nevertheless possibility does exist.

I have seen a variety of patients in our practice and I believe the medical literature would also support the same that oftentimes patients with a variety of different symptoms have been misdiagnosed for one condition and in fact they were experiencing thyroid condition. Some of those conditions would include depression and other psychiatric disorders, panic attacks, anxiety, depression, phobias, and obsessive-compulsive disorders which are commonly encountered in hypothyroidism and hyperthyroidism.  

Subclinical hypothyroidism is the most encountered organic cause of depression.  Reduced cardiac output in overt hypothyroidism: Cardiac contractility and cardiac output are decreased and vascular resistance is increased. These changes also affect people with clinical hypothyroidism but to a lesser degree.

High blood pressure: Hypothyroidism is often accompanied by diastolic hypertension that in conjunction with elevated cholesterol may promote atherosclerosis. Hypertension is relatively common among patients with laboratory evidence of hypothyroidism.

High cholesterol: Hypothyroidism is characterized by hypercholesterolemia and a marked increase in low-density lipoproteins and apolipoprotein A. These changes accelerate atherosclerosis which causes coronary artery disease.  

Subclinical hypothyroidism has been associated with endothelial dysfunction, aortic atherosclerosis, and myocardial infarction. Thyroid hormone replacement therapy may slow the progression of coronary artery disease.

Elevated C reactive protein: Clinical and subclinical hypothyroidism is associated with increased levels of low-grade inflammation as indicated by elevated C-reactive protein which may be a risk factor for the development of cardiovascular disease.

Other organ systems affected by Hypothyroidism:

Musculoskelatal system: Hypothyroid patients may exhibit joint aches and effusions and even pseudogout.

Reproductive system problems: In women, hypothyroidism is associated with menstrual irregularities, absence of ovulation, and infertility.

Pregnancy complications: Subclinical and postpartum hypothyroidism is gaining recognition as a serious health problem among women.

Several blood tests used actually measure thyroid function, one being TSH, thyroid stimulating hormone. This hormone is actually produced in the anterior pituitary gland of the brain, basically tells the thyroid to produce thyroid hormone. Another test commonly used is T3 and T4. These typically are protein-bound tests which do not give very much information in terms of truly how the thyroid is functioning. These tests should be performed in their preformed state or free state, T3 free, T4 free.

There currently is a great deal of controversy concerning thyroid hormone replacement therapies using synthetic thyroid hormone versus a more natural thyroid hormone such as Armour Thyroid. I will not discuss this in any detail, but we will move on to nutrients or nutritional supplements that actually enhance thyroid production.

Nutritional supplements which have shown to be effective in improving thyroidism performance:

Iodine and minerals: Iodine is required by the body to form thyroid hormone and iodine deficiency can lead to goiter which is an enlargement of the thyroid or hypothyroidism.  

Zinc is another supplement that is extremely important in the production of thyroid hormone, especially T3.  

Selenium is required for appropriate thyroid hormone synthesis, activation, and metabolism. Adequate selenium supports efficient thyroid hormone synthesis and metabolism and protects the thyroid gland from damage caused by excessive exposure to iodide.  

Vitamins: Several research studies have suggested that antioxidant vitamins such as vitamin C and E can reduce the oxidative stress caused by hypothyroidism. If you have been experiencing any of these symptoms that have previously been mentioned, it certainly warrants contacting your physician or a qualified healthcare provider to discuss these symptoms. As I previously stated, thyroid dysfunction and some other symptoms associated with that have often times been misdiagnosed.  The proper blood studies, as I said previously, thyroid stimulating hormone (TSH) should be checked. Free T4, free T3, thyroid peroxidase and as well as thyroid antibody should also be tested in evaluating thyroid function. Once determining the functional status of the thyroid, the best treatment plan can be recommended for you. 
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