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A metabolic approach to hypothyroidism.

The body makes more than one type of thyroid hormone. T2, which is diiodothyronine; T4, which is thyroxine; and T3, which is triiodothyronine. The thyroid gland is the body regulator. Consequently, lack of optimal levels of the body's thyroid hormones will affect every metabolic function in the body.

The signs and symptoms of hypothyroidism are numerous:

* agitation o allergies

* anxiety/panic attacks

* arrhythmias

* blepharospasm

* brittle nails

* carpal tunnel syndrome

* coarse, dry hair

* cold hands and feet

* constipation

* decreased cardiac output

* decreased memory

* decreased sexual interest

* deposition of mucin in connective tissues

* depression

* diffuse hair loss

* dizziness/vertigo

* down-turned mouth

* drooping eyelids

* dry, itchy ear canals

* dull facial expression

* dysmenorrhea

* elbow keratosis

* endometriosis

* excess formation of cerumen

* fat buildup at the clavicles

* fatigue

* fibrocystic breast disease

* fluid retention

* gallstones

* headaches

* high blood pressure

* hoarse, husky voice

* hypercholesterolemia

* hyperinsulinemia

* hypoglycemia

* hypotension

* inability to concentrate

* increased appetite

* increased risk of developing asthma

* increased susceptibility to bruising

* infertility

* insomnia

* intolerance to cold temperatures

* iron deficiency anemia

* irregularities in menstrual cycle

* joint pain or stiffness

* loss of hair from legs, armpits, arms

* loss of outer one-third of the eyebrows

* loss or thinning of eyelashes

* low body temperature

* mild elevation of liver enzymes

* morning stiffness

* muscle and joint pain

* muscle cramps

* muscle weakness

* muscular pain

* nocturia

* nutritional imbalances

* paramnesias


* poor circulation

* poor night vision

* produces abnormal waves on ECG

* puffy face

* recurrent miscarriages

* reduced heart rate

* rough, dry skin

* sleep apnea

* slow movements

* slow speech

* slower reflexes

* wollen body, especially legs, feet, hands, and abdomen

* swollen eyelids

* tinnitus

* weight gain

* yellowish coloring of the skin

Even though patients may have symptoms of hypothyroidism, it does not necessarily mean that they need to be started on thyroid medication. Looking at the cause of thyroid dysfunction is very helpful. T3 is five times stronger than T4. So anything that affects the conversion of T4 to T3 can give the patient symptoms of hypothyroidism.

The following are factors that may cause an inability to convert T4 to T3:

* aging process

* high-dose alpha lipoic acid (600 mg or more qd)

* calcium excess

* medications

* beta-blockers

* chemotherapy

* estrogen replacement therapy

* lithium

* oral contraceptives

* phenytoin

* theophylline

* copper excess

* diabetes

* dietary factors

* excessive alcohol intake

* low-carbohydrate diet

* low-fat diet

* low-protein diet

* soy

* too many cruciferous vegetables

* too many walnuts

* dioxins

* fluoride

* inadequate production of DHEA or Cortisol

* lead toxicity

* mercury toxicity

* nutritional deficiencies

* iodine

* iron

* selenium

* vitamins A, B2, B6, and B12

* zinc

* PCBs

* pesticides

* phthalates

* radiation

* stress

* surgery

Furthermore, the conversion of T4 to T3 requires the enzyme 5'-deiodinase. There are three types of deiodinases. Type 1 is located in the thyroid, liver, and kidneys and plays an important role in the production of T3. Type 2 is found in the pituitary, hypothalamus, and brown fat and converts T4 to T3. Type 3 catalyzes deiodination of the inner ring of T4 and T3, which inactivates the hormone. Factors that affect 5'-deiodinase production include selenium deficiency, cadmium, mercury, or lead toxicity, starvation, inadequate protein intake, high-carbohydrate diet, elevated cortisol levels, chronic illness, and decreased kidney or liver function. Inflammation also affects 5'-deiodination production.

Likewise, iron deficiency anemia can impair the body's response to T3, which may also give the patient symptoms of hypothyroidism. Some patients may benefit from detoxification of the GI tract and/or liver, which may additionally improve thyroid function. Furthermore, various factors may improve the conversion of T4 to the more active T3, including Ashwagandha, glucagon, growth hormone, high-protein diet, insulin, iodine, iron, melatonin, potassium, selenium, testosterone, thyrosine, vitamins A, B2, and E, and zinc.

There are also components that are associated with low T3 or increased reverse T3. Bettering these factors may improve thyroid function:

* aging process

* diabetes

* elevated levels of IL-6 or TNF-alpha

* fasting

* free radical production

* increases epinephrine or norepinephrine

* prolonged illness

* stress

* toxic metal exposure

Likewise, if the reverse T3 level is elevated, then it will further inhibit the conversion of T4 to T3. Causes of abnormal reverse T3 levels should be treated, such as yo-yo dieting, heavy metal toxicity, infections, and physical and mental stress. Also, elevated reverse T3 is common in chronic fatigue syndrome and fibromyalgia. Free T3 and reverse T3 occupy the same receptor sites; however, T3 activates the receptor and reverse T3 does not. Consequently, if reverse T3 is high, the patient will have symptoms of hypothyroidism, even if the patient's labs are otherwise normal. Since reverse T3 is derived from T4, then lowering the patient's T4 dose or taking the patient off T4 will aid in lowing reverse T3 levels. Also, prescribing T3 will lower the TSH and subsequent production of T4 by the thyroid gland and inappropriate conversion of reverse T3. Furthermore, decreasing stress, growth hormone replacement, and giving selenium or iodine if the patient is deficient in either nutrient will lower reverse T3 levels.

If the etiology of the problem cannot be found and resolved in order to restore optimal thyroid function, medication may need to be used. Medical studies have shown that many patients benefit from replacement of both T3 and T4. Ninety percent of thyroid hormone molecules that bind with thyroid receptors are T3; the remainder are T4. T3 has a direct effect on the mitochondria and heart. Consequently, giving desiccated thyroid hormone (T3 + T4) may be the optimal treatment for many patients or to have their thyroid medicine compounded by a compounding pharmacy. Thyroid medication should also be taken on an empty stomach, since calcium in vitamins or calcium contained in foods can interfere with the absorption of thyroid medication. The following drugs or agents can also affect thyroid absorption, usage, and excretion:

* aluminum hydroxide

* amiodarone

* bile acid sequestrants

* carbamazepine

* cimetidine

* clomiphene

* Dilantin

* ferrous sulfate

* haloperidol

* lactose

* lithium

* metoclopramide

* oral contraceptives

* phenobarbital

* phenytoin

* rifampin

* ritonavir

* sertraline

* sucralfate

It is also important to consider the health of the patient before prescribing thyroid hormone replacement. It is imperative to make sure that the adrenal glands are functioning optimally before giving a patient thyroid medication. If the patient has hypoadrenalism (adrenal fatigue), then treatment of the adrenal fatigue should commence for six to eight weeks before starting thyroid medication. Likewise, if the patient has had an acute myocardial infarction, then the prescriber should wait at least two months after the diagnosis before instituting thyroid replacement. Furthermore, low magnesium levels and chronic exposure to mold may interfere with patients' ability to tolerate thyroid hormone supplementation. Additionally, iron levels must be optimal for perfect thyroid function. Ferritin levels should be over 100 ng/ml. If a woman is cycling, then ferritin levels of over 130 ng/ml are suggested.

Some patients may be resistant to thyroid medication. This phenomenon may be related to mitochondrial dysfunction. Other genetic thyroid problems can occur. Over 100 different mutations have been found in one of the primary genes for thyroid receptors. Receptors that are not functioning optimally may prevent a sufficient supply of hormones that are in the blood from reaching the mitochondria and the nucleus of the cell.

Hypothyroidism may be associated with other diseases such as attention deficit/hyperactivity disorder, cardiovascular disease, chronic fatigue, fibromyalgia, and depression. A low ratio of T3 to reverse T3 is a predictor of mortality in congestive heart failure patients. Also, in people with chronic congestive heart failure, V-tach is associated with low T3 or increased reverse T3 levels. Furthermore, low T3 is predictive of an increased risk of developing atrial fibrillation post coronary artery bypass graft (CABG) surgery. Having an elevated reverse T3 level is a strong predictor of mortality in the first year after an acute myocardial infarction. Likewise, elevated levels of homocysteine and CRP may be more common in patients with hypothyroidism.

In conclusion, optimal thyroid function requires adequate nutritional intake. Hypothyroidism may have many etiologies such as toxin exposure, other hormonal dysfunction, and medication usage, to name a few. It is paramount to look at the etiologies of thyroid dysfunction before considering thyroid hormone replacement. When a prescription is needed, most patients require replacement of both T3 and T4 to optimize thyroid function.

This article is an excerpt from: P. Smith, What You Must Know About Women's Hormones. Garden City Park: Square One Publishers; 2010.

References to this article are located in that text.

by Pamela W. Smith, MD, MPH

Director of the Fellowship in Anti-Aging, Regenerative, and Functional Medicine Codirector of the Master's Program in Medical Science with a concentration in Metabolic and Nutritional Medicine, University of South Florida College of Medicine
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Author:Smith, Pamela W.
Publication:Townsend Letter
Article Type:Report
Geographic Code:1USA
Date:Jan 1, 2012
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