Thyroid Function

The thyroid is a small butterfly-shaped gland located in the front of the neck. The hormones of the thyroid gland regulate the metabolism of every cell in the body and an imbalance will affect virtually every body function. An underactive thyroid causes the body’s metabolic rate to slow down. Common symptoms are fatigue, increased need for sleep, weight gain, depression, and general apathy. A general sensitivity to cold, recurrent infections, menstrual problems, dry skin, hair loss and memory or concentration problems is typical. The palms of the hands can become carrot-colored, the face puffy and the muscles and joints can become stiff and achy.

Deficiency of thyroid hormone may be due to lack of stimulation from the pituitary gland, defective hormone synthesis or impaired conversion of the less-active hormone T4 to the active hormone T3. The T3 thyroid hormone is four times more active than T4 inside your cells. The pituitary gland regulates the production of thyroid hormone by releasing TSH (thyroid stimulating hormone) which tells the thyroid to make more T4. The T4 hormone is then released from the thyroid gland to travel to every cell in your body. The cells will then take the T4 hormone, convert it to the more active T3 increasing the utilization of fat, protein and carbohydrates in the metabolic processes of the cell.


The combination of high TSH and low thyroid hormone (T4) usually indicates that the body is not making enough thyroid hormone and is defined as primary hypothyroidism. When the TSH produced by the pituitary as well as the thyroid hormone (T4) is low, the pituitary is responsible for low thyroid function and this is termed secondary hypothyroidism. The third cause of low thyroid function is called cellular hypothyroidism and medically shows up as normal blood values of T4 and TSH. In cellular hypothyroidism the less-active hormone T4 is poorly converted to the active hormone T3.

About 95% of the cases of low thyroid function are primary; in other words the thyroid gland is not able to properly synthesize enough thyroid hormone. The thyroid hormone T4 is made by adding iodine to the amino acid L-tyrosine. In the past the most common cause of hypothyroidism was iodine deficiency. Often an iodine deficiency will lead to the development of an enlarged thyroid gland commonly called a goiter. Due to the addition of iodine to table salt, an iodine deficiency is rare in modern times. People who still develop goiters may be ingesting too much goitrogens-food that block iodine utilization. These foods include turnips, cabbage, mustard, soybean, peanuts and millet. Cooking usually inactivates goitrogens.

Currently the most frequent cause of hypothyroidism is Hashimoto’s disease, an inflammation of the thyroid gland caused by an attack of the body’s own immune system. The cause of the autoimmune reaction is presently unknown. Women are the most susceptible to hypothyroidism during times of stress, menopause and pregnancy. Further causes can include chemical pollutants, such as pesticides and PCB’s that leak into food and water blocking receptors or causing DNA damage to the cells.

The diagnosis of hypothyroidism by laboratory methods is primarily based on the results of TSH and T4 levels. The problem is that a person may be suffering from sub-clinical hypothyroidism even though the blood tests may come back normal. Functional thyroid activity can be determined by measuring basal body temperatures and by a clinical assessment of the signs and symptoms of hypothyroidism. For example if a person has low basal body temperatures, fatigue, dry skin, and depression they may be suffering from hypothyroidism though their blood values are normal. Basal body temperatures are measured under the armpit before rising in the morning starting the second day of menstruation with a normal temperature being 36.6-36.8 C.

Dietary treatment of hypothyroidism should begin with adequate nutrition and exercise. Exercise stimulates the thyroid gland and increases cellular sensitivity to the thyroid hormone. The diet should be low in goitrogens and high in foods rich in the trace minerals zinc, copper and selenium as well as iodine. Good sources of iodine include sea fish, sea vegetables (kelp, arame, nori, wakame, dulse, kombu) and iodized salt. The maximum recommended dose of iodine is 600mcg/day for any length of time because too much iodine can actually inhibit the thyroid gland. Sources of zinc include seafood, liver, chicken, oatmeal, spinach, nuts and seeds. Copper is found in organ meats, beans, nuts, seeds and eggs. Selenium is high in brazil nuts, seafood, chard, and orange juice. The vitamins riboflavin (B2), niacin (B3), pyridoxine (B6), vitamin E and Vitamin C are also necessary for normal thyroid hormone production. The best sources of the B-vitamins are nutritional yeast, whole grains and liver. Good dietary sources of vitamin E include wheat germ oil, sunflower seeds, almonds and pecans. Vitamin C sources include acerola berries, orange juice, peppers and other citrus. The amino acid L-Tyrosine is the backbone of the thyroid hormone and can be found in higher amounts in cheese, wild meats, granola, chocolate, yogurt and oatmeal.


In the case of hypothyroidism if nutritional and lifestyle intervention do not re-establish normal thyroid activity, prescription of thyroid hormones is necessary. Although synthetic hormones such as synthroid or levothyroid containing T4 are most commonly prescribed, there are other choices. Some people find that they still have hypothyroid symptoms while being on Synthroid and may actually do better with a combination therapy of both T4 and T3. Many naturopathic doctors prefer the use of desiccated natural thyroid that contains both T4 and T3 hormones. The main concern over the natural alternatives is that it can lack consistency. The other choice is a combination of synthetic T4 and T3 which provides the consistency that whole natural desiccated is thought to lack. Thyroid hormone therapy is recommended to be taken on an empty stomach to increase absorption.

About 2% of people suffer from hypothyroidism. Since thyroid dysfunction can mimic other health concerns and it is important to address any health concerns with a qualified doctor.

The two major thyroid hormones are triiodothyronine (T3) and thyroxin (T4). Daily production of the thyroid gland is about 80 – 100 micrograms of thyroxin and 20 micrograms oftriiodothyronine. T3 is by far the main thyroid hormone found in the target cells. Its volume of distribution in the human body is 3 – 5 times greater than that of T4. The daily production and plasma levels of T4 and T3 generally decline with age, favoring the appearance of a clinical syndrome called hypothyroidism.

Thyroid Hormone Deficiency Syndrome



Puffy face and swollen eyelids

Morning fatigue

Dry skin and hair

Somnolence or sleepiness

Diffuse hair loss


Cold hands and feet



Headache or migraine

A pinched blood pressure

Sensitive to cold

A tendency to weight gain or obesity

Morning stiffness

Slow Achilles tendon reflexes

Muscle & joint pain

Carotene color of the soles of the feet

Menstrual disorders

Treatment of Thyroid hormone deficiency

Different thyroid preparations are sold on the market today. The most frequently prescribed contains only of the thyroid hormones. T4, but others can contain T3 alone and finally, a combination of T4 and T3 either as a mixture or as desiccated thyroid from animal origin. However, according to Thierry Hertoghe, MD, a world-recognized leader in clinical endocrinology, thyroid hormone replacement therapy is best done with prescriptions that contain both T4 and T3.