The thyroid gland is a butterfly-shaped gland located in the lower part of the neck. Though it weighs less than an ounce, the thyroid gland is responsible for many critical functions in the body. Every single muscle, organ and cell in the body depends on adequate thyroid hormone levels for achieving and maintaining optimal functioning.
Thyroid hormone acts as the body's metabolic regulator. In a hypothyroid state, the thyroid gland is releasing inadequate amounts of thyroid hormone to meet the body's metabolic demands, and the metabolic rate is therefore reduced. In a hyperthyroid state, the thyroid gland is releasing excess amounts of thyroid hormone that results in an elevated metabolic rate.
The thyroid gland secretes approximately one teaspoon of thyroid hormone over an entire year. This teaspoon of thyroid hormone must drive the metabolic rate of every single cell in the body. Small variations in this amount will have wide ramifications on the health of the individual.
It is impossible for the body to function at an optimum level of health if there is inadequate production of thyroid hormone. What happens when the thyroid gland produces an inadequate amount of thyroid hormone? A constellation of symptoms develops. These symptoms are collectively referred to as hypothyroidism.
These are the signs and symptoms of hypothyroidism:
Brittle nails, Cold hands and feet, Cold intolerance, Constipation, Depression, Difficulty swallowing, Dry skin, Elevated Cholesterol, Essential Hypertension, Eyelid swelling, Fatigue, Hair loss, Hoarseness, Hypotension, Inability to concentrate, Infertility, Irritability, Menstrual Irregularities, Muscle Cramps, Muscle Weakness, Nervousness, Poor memory, Puffy eyes, Slower heartbeat, Throat pain, and Weight Gain.
How Common Is Hypothyroidism?
The prevalence of hypothyroidism is staggering. The Colorado Thyroid Disease Prevalence Study estimated that the rate of hypothyroidism in the general population was approximately 10%. In the United States, this may mean that 13 million adults have an undiagnosed hypothyroid condition.
Although this study used blood testing alone to diagnose a hypothyroid condition, my research has shown that relying solely on blood tests for this diagnosis will result in missing at least 30% of those who have a hypothyroid condition. A holistic approach, which takes into account the laboratory tests, the basal body temperatures as well as the patient's signs and symptoms will identify many more individuals suffering from hypothyroidism. It is my opinion that the true figure for hypothyroidism is closer to 40% of the population or approximately 52 million adult Americans.
The thyroid gland produces two major hormones, Thyroxine (T4) and Triiodothyronine (T3). These two hormones work inside the cells of the body, primarily influencing the metabolism of the cells. In other words, thyroid hormone helps the cell machinery produce energy.
When there is an adequate amount of thyroid hormone, the cell machinery functions normally and the metabolism of the cells (and the body) occurs at a normal level. When there is an inadequate amount of thyroid hormone produced (i.e., hypothyroidism), the metabolism of the cells (and the body) will decline, and the signs and symptoms of hypothyroidism will be present.
The thyroid produces much more T4 (approximately 80%) than T3 (approximately 20%). T3 is much more active than T4 (about 300% more active) and T3 is the thyroid hormone that actually increases the metabolism inside the cells. The majority of T4 is actually converted into T3 inside the cells of the body.
How Is Hypothyroidism Diagnosed? The Conventional Approach
The conventional approach to diagnosing hypothyroidism primarily revolves around the measurement of thyroid blood tests, primarily the thyroid stimulating hormone (TSH) test. TSH Normal Range: 0.4-4.5mIU/L, TSH Hypothyroid: > 4.5mIU/L.
If the TSH is elevated, it is a sign that the pituitary gland is sensing a low thyroid hormone level in the body, and the TSH is being secreted in order to stimulate the thyroid gland to produce more thyroid hormone. If the TSH test is normal, many physicians believe that automatically rules out a hypothyroid state.
The Problems with the TSH Test
The TSH test has been the ‘gold standard' in conventional medicine for diagnosing hypothyroidism for over 30 years. The normal range for the TSH test reported in most laboratories is from 0.4 - 4.5 mIU/L. When TSH values fall above this range (i.e., >4.5mIU/L), a diagnosis of hypothyroidism is given.
This reference range was established to include 95% of the population. Therefore, 5% of the population, which falls outside of this reference range, should be classified as having a thyroid disorder. However, as reported in the Colorado Thyroid Study (mentioned above), many researchers believe that the true incidence of hypothyroidism is significantly higher than 5%.
Dr. AP Weetman, professor of medicine, wrote in the British Medical Journal, "Even within the reference range of around 0.5-4.5 mIU/L, a high thyroid stimulating hormone concentration (>2mIU/L) was associated with an increased risk of future hypothyroidism.
The simplest explanation is that thyroid disease is so common that many people predisposed to thyroid failure are included in a laboratory's reference population, which raises the question whether thyroid replacement is adequate in patients with thyroid stimulating hormone levels above 2 mIU/L.
The high frequency of overt and subclinical hypothyroidism observed raises another contentious issue--namely, whether screening for hypothyroidism is worthwhile." It has been my experience that relying solely on the TSH test will result in under-diagnosing many individuals who are suffering from hypothyroidism - up to 30% of the population.
Should the TSH ‘Normal' Range be Changed?
There is great controversy in conventional medicine about where the ‘normal' TSH range should be set. There are many physicians and organizations who believe the ‘normal' upper limit of the TSH range should be lowered from 4.5mIU/l to 3mIU/l.
This small change may result in a doubling of the numbers of individuals diagnosed as hypothyroid via blood tests - from approximately 13 million to 26 million individuals. My experience has clearly shown the TSH reference ranges need to be altered. The present TSH ‘normal' Range is 0.5 - 4.5 (mIU/L). A proposed TSH ‘normal' range that is much more clinically relevant would be 0.5 - 2.0 (mIU/L).
So, what should be the ‘normal' TSH range? It is not an easy question to answer. It must be understood that the TSH test is only one measure of thyroid function. I do not think the TSH test should be used as the sole test, without regard to other lab tests, the physical exam as well as the history of the patient. Each patient is a unique biochemical individual. Some may do better at a TSH of 1.0mIU/L, while another may do better at a TSH of 3.0mIU/L.
That is why it is so important to do a complete holistic workup which includes looking at the rest of the thyroid blood tests as well as evaluating the nutritional status of the patient. Only with a complete holistic approach can you achieve the best results. Having said that, my experience has shown that the vast majority of patients have optimal thyroid function when the TSH is between 0.3-2.0 mIU/L.
(This article was excerpted, in part, from Overcoming Thyroid Disorders, 2nd Edition)
1. Canaris, Gay, et al. The Colorado Thyroid Disease Prevalence Study. Arch. Intern. Med. Vol 160, Feb 28, 2000
2. Harrison's Principles of Internal Medicine. 14th Edition. 1998
3. Weetman, A.P. "Fortnightly review: Hypothyroidism: screening and subclinical disease." British Medical Journal. 1997;314:1175 919 April
Dr. David Brownstein, M.D.
David Brownstein, M.D. is a family physician who utilizes the best of conventional and alternative therapies.
He is the Medical Director for the Center for Holistic Medicine in West Bloomfield, MI.