Hair trace elements and hypothyroidism - Letters to the Editor - Letter to the Editor

Townsend Letter for Doctors and Patients, Feb-March, 2004 by David L. Watts

Editor:

As a Clinical Psychologist and Licensed Nutritional Consultant, Dr. Malter has a unique and keen insight into the psychophysiology of stress and its reflection in hair tissue mineral analysis (HTMA) patterns. His experience of using HTMA for evaluating the mind/body interaction spans over 20 years. An excellent point is raised by his commentary, in that a majority of people experiencing physical and emotional problems fall outside the "medical/disease" model. They can be classified as having sub-clinical conditions, i.e. falling within the normal medical ranges, but experiencing real physical and emotional symptoms. This is particularly true in relation to thyroid dysfunction.

As Dr. Malter mentioned, we often see patients with many of the classic symptoms of hypothyroidism, particularly depression, yet their thyroid function may show no clinical abnormality according to the "medical/disease" model. The HTMA can often provide insight into their sub-clinical conditions.

Occurrence of Hypothyroidism

It has been estimated by Barnes, et al., that 40% of the American population suffers from hypothyroidism and is the most common complaint seen by doctors in this country. (1) This estimation was made over 25 years ago and if we include sub-clinical hypothyroidism we can conservatively raise this estimation to over 50%. Severe clinical hypothyroidism is readily evident from blood tests, however sub-clinical thyroid insufficiency is not easily detected through normal tests. I have described sub-clinical hypothyroidism as a syndrome rather than a disease and is characterized by fatigue, depression, cold sensitivity, weight gain and changes in the texture of the hair and skin.

Thyroid insufficiency affects females at a greater frequency than males. From our database of over 2,000 patients submitted with hypothyroid predominate symptoms, 90% were females. The reason for this gender difference has been discussed elsewhere and will not be reviewed here. (2)

Nutrition and the Thyroid

Iodine

There are a number of nutrients that affect the thyroid. The most recognized being iodine. Iodine deficiency is associated with endemic colloid goiter--a condition that occurred in areas of low iodine soils prior to its prevention with the introduction of iodized salt. Idiopathic nontoxic goiter is identical to endemic goiter but is not associated with iodine. In fact, iodides can actually reduce all thyroid gland activities by inhibiting thyrotropin--possibly by inhibiting the hypothalamus. Reduced thyroid activity is often seen even in the presence of normal iodine levels. (3), (4) A great deal of emphasis is placed upon iodine in assessing thyroid status, but there are many other factors that are important.

Iron and Vitamin A

Iron and vitamin A deficiencies are prevalent in areas of endemic goiter, although iodine intake is adequate. It is now recognized that the response to iodine therapy is ineffective in the presence of iron deficiency. Iron is required for the conversion of L-phenylalanine to L-tyrosine and may be reduced by over 50% with iron deficiency. Many patients with hypothyroidism respond to vitamin A therapy. (5)

Selenium, Zinc and Chromium

Selenium deficiency can contribute to hypothyroidism due to its involvement in the conversion of T4 to active T3. Selenium is a constituent of the enzyme 1 iodothyronine deiodinase (IDI), an enzyme responsible for the peripheral conversion of T4 to T3 in the liver and kidneys. This enzyme is markedly reduced in selenium deficiency. (6)

Zinc influences the secretion of thyroid-stimulating hormone (TSH). Therefore, zinc deficiency or a low zinc to copper (Zn/Cu) ratio can be involved in lowered thyroid expression.

A number of research studies have found an interaction between chromium and thyroid activity. The mechanism is not yet understood, however this association may be explained through HTMA patterns. (7)

Thyroid Antagonists

Nutritional

Goitrogens are naturally occurring anti-thyroid substances found in foods that adversely affect the thyroid. These are commonly known foods and therefore will not be discussed here. Other nutritional factors known to inhibit thyroid function include: Calcium, Vitamin D, Cobalt (B12), PABA, Molybdenum, Bromine, Copper, Lithium, Lead and Mercury.

Endocrine

Hormones antagonistic to the thyroid include: Estrogen, Insulin, Parathyroid.

HTMA Patterns Associated with Decreased Thyroid Expression

The most common metabolic type indicating diminished thyroid activity in HTMA patterns is the Slow Metabolic Type 1. This neuroendocrine pattern indicates parasympathetic dominance. The primary TMA ratios found with reduced thyroid activity include:

Elevated Ca/P (>2.63)

Elevated Ca/K (>4.2)

Elevated Ca/Mg (>7)

Reduced Zn/Cu (<8)

Reduced Fe/Cu (<0.9)

Reduced Na/Mg (<4)

Reduced K/Co (<2000)

Reduced K/Li (<2500)

Reduced Fe/Pb (<4.4)

Reduced Fe/Hg (<22)

Reduced Se/Hg (<0.8)

Reduced Zn/Cd (<500)

Reduced Zn/Hg (<200)

Elevation of the Ca/Mg ratio indicates a relative increase in parathyroid hormone as well as insulin production. A reduced Zn/Cu ratio indicates a reduction in progesterone relative to estrogen in the female. The relationship of chromium and thyroid activity could be explained by chromium's effect upon insulin sensitivity. Reducing insulin levels would result in improved thyroid hormone activity. The increased cellular immune response common in the Slow Metabolic type could contribute to thyroid disorders due to an autoimmune response.