By Kim Furtado, N.D

When a post-menopausal woman recently presented to my office with serious concerns of hypothyroidism which was diagnosed at age 35, she described what a majority of my clients reveal.  Simply the management of thyroid hormone dosing has not proven to alleviate her suffering.  Many clients, despite being on significant doses of replacement hormone, still feel terrible.  Tired all the time, and at wits end with many clinical concerns, they turn to naturopathic medicine to understand better the root cause of their symptoms.

These women exhibit persistent signs and symptoms of hypothyroidism including weight gain with diminished food intake, extreme fatigue, cold intolerance, constipation, poor circulation, fluid retention, ringing in the ears, poor memory, dry skin and hair, hair loss, broken nails, and slow thinking.

Certain lab values may or may not be altered with hypothyroidism. Sometimes the labs fluctuate, or sometimes women report their doctors will only monitor using one lab test, TSH.  Commonly also, women may have normal TSH, but exhibit all the symptoms of an under-functioning thyroid gland.

Complete blood counts may show anemia; chemistry screen’s may show elevated serum cholesterol; thyroid panel’s may show decreased T3 uptake, total T4 and free T4 with elevated TSH,  Some patients may not exhibit any laboratory changes, but have low basal body temperature readings.  If auto-immune labs were even checked, often they are coming back positive, indicating another layer of pathology.

So how is it by treating the root cause of disease can anyone get their thyroid back online?  First and foremost, we look to the liver’s function. Because while the thyroid hormone is produced by the gland (or dosed as medicine), the body still has to be able to metabolize it and utilize it. That conversion is mostly done by the liver, and if someone is not responding to thyroid medicine properly or has the symptoms of hypothyroid and is told by a doctor that the labs are normal, it is possible that the real problem lies in how efficiently the liver is doing its job to send activated thyroid hormone to the cells to use.


And guess what disrupts this process?  Yes, commonly found pollutants in our environment can disrupt our endocrine system.  And yes, improving liver function through nutrition, herbal medicine and stress management tools are often the only way to regain function of thyroid hormone.  Detoxification is what gets the fatigue to lift, the metabolic rate to be healed so that weight loss can be achieved.  Resolving many chronic symptoms of thyroid disorder can begin with effective detoxification support and targeted nutritional therapy.

The main chemicals that affect thyroid function are:

Polychlorinated biphenols (PCBs) and Dioxins. PCB’s were once used in electrical transformers, capacitators, plasticizers and adhesives. Although many are no longer used in the U.S. they still persist in the environment. Dioxin is formed as a by-product of industrial processes involving chlorine such as waste incineration, chemical and pesticide manufacturing and paper bleaching.  The main way we are currently exposed to dioxins and PCB’s is through our food. It is a contaminant in meat, dairy and fish.

PCB’s and Dioxins induce thyroid hormone metabolism through an enzyme called UDP-glucuronyl transferase. This simply means they alter liver function of the enzyme that metabolizes thyroid hormone. They also directly attack the thyroid gland and thyroid hormone carrier proteins. There are numerous studies linking PCBs and Dioxins to thyroid dysfunction.

Pesticides have also been linked to thyroid disease in numerous studies. We are exposed to pesticides everyday whether we chose to be or not. They contaminate our air, water, food, soil, playground equipment, personal care products and more. There are numerous studies that link pesticides to thyroid dysfunction. Specifically Maneb and mancozeb which are sprayed on fruits such as bananas and has been found to alter thyroid stimulating hormone (TSH), inhibit thyroid peroxidase enzyme, and cause thyroid nodules.

A study of women married to men who sprayed pesticides on agriculture for a living had increased rates of thyroid disease. The study was published in the American Journal of epidemiology, online, January 8th 2010. It looked at 16,500 women living in Iowa and North Carolina who were married to men using pesticides at work in the 1990’s. 12.5 percent of the women developed thyroid disease. This is a 1.2 to 1.4 fold increase than the general female population. It is interesting to note that these women didn’t actually use the pesticides themselves but were exposed second-hand through their husbands.

Pentachlorophenol (PCP) is a chemical used in industry and agriculture. We are exposed without even knowing it exists. It is used as a wood preservative and produces toxic by-products that contaminate our air, food and water. It too is linked to alteration of thyroid hormones and the formation of a goiter. A goiter is an enlargement of the thyroid gland. It is not cancer but typically is a signal that something is wrong with the gland.

Bisphenol-A (BPA) is another common chemical that we are exposed to everyday through the lining of metal food cans, dental sealants and plastic bottles. It too is linked to thyroid disorders. Even at low doses consistent with what the average person would be exposed to there are links to changes in thyroid hormones.

Heavy metals are found to affect the thyroid as well. One of the main heavy metals studied is cadmium. Cadmium is a component of cigarette smoke and a product of industry. It is in the air, soil and water of most cities. We are exposed through cigarette smoke, food grown in contaminated soil, air pollution and water contamination. There are numerous studies linking thyroid disease to cadmium exposure. In one study 636 children in Germany had their blood tested for thyroid hormones and correlated abnormalities to urine and blood levels of heavy metals. It was determined that children with alterations in thyroid hormones had high blood levels of cadmium.

Mercury is also linked to thyroid disease in women and children. Methylmercury, which is found in fish, is linked to alterations in thyroid hormones via the mechanism of depleting selenium. Selenium is a mineral that is essential for proper thyroid function.

Lead is another heavy metal that we are exposed to on a daily basis through our food, air and water. It too is linked to thyroid disorders in many studies. One of note shows how sensitive a woman’s hormonal system is compared to men. Women’s hormones appear to be more interconnected than men’s hormones. For example many women develop thyroid disease during pregnancy due to increases in estrogen and progesterone. One study compared men and women’s blood levels of lead and mercury to alterations in thyroid hormones and found women were more affected by the heavy metals.

Perfluorooctanoic Acid (PFOA) is found in stain and water resistant coatings for carpet, furniture, fast-food containers, paints, and foams. We are often exposed without knowing. These chemicals build up in our adipose tissue, or fat, and alter thyroid function. The National Health and Nutrition Examination Survey (NHANS) looked at 3,973 adults and measured PFOA levels. It determined high concentrations of PFOAs are linked to thyroid disease.

Halides (such as Bromines, Chlorine, Fluoride) Bromines are common endocrine disruptors and can be found in a number of places in your everyday world, including pesticides, plastics (used to make computer), bakery goods, soda, medications, fire retardants, and bromine-based hot tub and swimming pool treatments.

Because these compounds are halides, they compete for the same receptors that are used in the thyroid gland (among other places) to capture iodine. This can inhibit thyroid hormone production resulting in a low thyroid state.


Learn more at the Collaborative for Health and the Environment  about public health minded health care providers’ work, policy guiding white papers, and search their online Toxicant and Disease Database for lists of chemicals that affect various health issues.

Thyroid disorders – hypothyroidism

Causes    Grouped by strength of evidence

Strong Evidence


ionizing radiation


PCBs (polychlorinated biphenyls), not otherwise specified


radioactive iodine (I131)









Good Evidence


dioxins / TCDD

ethylene thiourea (ETU)












Limited Evidence


carbon disulfide







organochlorine pesticides


PBDEs (polybrominated diphenyl ethers), not otherwise specified

pentachlorophenol (PCP)