Friday, June 14, 2024

Why Screening and Commonly Prescribed Thyroid Drugs Often Fail to Relieve Symptoms

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By Dr. Mercola

Your thyroid gland, located in the front of your neck, influences almost every cell in your body. Thyroid hormones regulate your metabolism, and are required for growth and development in children and nearly every physiological process in your body.

When your thyroid levels are unbalanced, it can spell trouble for your overall health and wellness. Evidence suggests nearly 60 percent of people with suboptimal thyroid function are unaware of their condition.1 While prevalent, it is often easily treatable and may reverse symptoms of other health conditions.

Poor thyroid function is linked to health conditions such as fibromyalgia, irritable bowel syndrome, eczema, gum disease and autoimmune disorders. Symptoms of low function and the health conditions affected by low levels are varied, as the hormone is used throughout your body.

Women are five to eight times more likely than men to have low thyroid function and 1 in 8 women will develop a thyroid disorder in her lifetime.2 Understanding the basics of how your thyroid functions and what may cause a dysfunction is important to your overall health.

Thyroid Function

Your thyroid gland is shaped like a butterfly on your neck just under your voice box and secretes four hormones: T1, T2, T3 and T4. The number indicates the number of molecules of iodide attached to the hormone. These hormones interact with other hormones, such as insulin, cortisol and sex hormones.

Your hypothalamus secretes thyrotropin-releasing hormone (TRH) that triggers the pituitary gland to release thyroid stimulating hormone (TSH) that then causes your thyroid to release T4. Almost 90 percent of your thyroid hormone is released in an inactive form of T4. Your liver then converts T4 to T3 with the help of an enzyme. T2 is currently the least understood form of thyroid hormone and is the subject of a number of ongoing studies.

When everything is working properly, your body makes enough T4 that is converted to T3 to control the metabolism of every cell in your body. T3 is critical in the communication of messages to your DNA to increase your metabolism by burning fat. In this way, it helps keep you lean. Nutritional imbalances, toxic exposures, allergens, infections and stress can disrupt this hormonal balance, leading to a series of health complications including hypothyroidism, hyperthyroidism and thyroid cancer.

Thyroid Cancer Acts Differently Than Other Cancers

You may have been swayed by advertisements from an industry-funded foundation3 to be screened for thyroid cancer, but the U.S. Preventive Services Task Force has added this screening process to their “don’t-do-it category” in recommendations published in the Journal of the American Medical Association.4

The task force believes the consequences of thyroid cancer screening far outweigh the benefits. Although most cancer screenings help detect early disease and increase the potential for successful treatment, in this case early screening may actually backfire.

In many cases thyroid cancer screening will yield a false positive result, finding cancers that would never grow into life-threatening tumors.5 However, once discovered, most physicians feel obligated to recommend treatment, which often includes removal of the thyroid gland, and which may have significant side effects.

Surgeons may accidently sever nerves that control speech and swallowing, or remove the parathyroid gland that regulates calcium levels in your body. In an accompanying editorial, Dr. H. Gilbert Welch, of Dartmouth Institute for Health Policy and Clinical Practice, discussed problems with overdiagnosis of thyroid cancer.

Data from the SEER program demonstrated the incidence of thyroid cancer had remained relatively stable until 1990, after which it tripled.6 However, more interesting is that despite this rapid increase, mortality from thyroid cancer has remained stable, an indication cancers are identified and treated that don’t require treatment. Welch said:7

“Patients with newly diagnosed thyroid cancer typically have been treated aggressively. As of 2013 in the United States, over 80 percent underwent total thyroidectomy and subsequently required lifelong thyroid replacement therapy.”

Do You Have Underactive Thyroid Function?

In this informative video, Dr. Jonathan Wright discusses the measurement of thyroid function and how it should be compared against symptoms you may be experiencing. This was demonstrated in a recent European study in which researchers compared results of treatment against lab testing and symptoms.8

The authors were interested in the clinical effectiveness of treatment with the drug levothyroxine (Synthroid) after patients were diagnosed with low thyroid function. The number of people diagnosed in the U.S. has risen to the point levothyroxine is the most prescribed medication, outdistancing statins in 2015.9

A study from Johns Hopkins found nearly 15 percent of all older Americans were taking levothyroxine.10 However, as popular as this medication appears to be, the European study found the drug had no significant effect on older Europeans with mild symptoms of hypothyroidism.11 Physicians often order a TSH test as part of a routine panel of blood tests, prescribing drugs when the numbers are slightly elevated, although the patient may not complain of significant symptoms.

The study participants had higher than normal TSH level at least twice and had complaints of being tired. The researchers assessed cognitive speed, hand strength, weight and blood pressure prior to splitting the group, giving half levothyroxine and half a placebo. After one year of intervention, the researchers found TSH levels returned to normal in the group taking the drugs, but the participants’ complaints did not improve over the year in either group.

Flame-Retardant Chemicals Affect Thyroid Function

The researchers attributed the changes in TSH levels to age in the population studied, as the average participant was 74 years. However, other research has demonstrated environmental toxins may be responsible for a change in your thyroid function, and even for an increasing number of papillary thyroid cancer.12

Lead researcher Dr. Julie Ann Sosa, professor of surgery and medicine at Duke University School of Medicine, said, “Recent studies suggest that environmental factors may, in part, be responsible for this increase.” The research focused on polybrominated diphenyl ethers (PBDEs), a class of flame-retardant chemicals.

Previous animal studies had demonstrated a link between PBDEs and thyroid function, so Sosa and her colleagues collected dust samples from the homes of 140 participants already diagnosed with papillary thyroid cancer who had lived in their home an average of 10 years.

The researchers used blood samples to assess exposure to PBDEs and found those living in homes with high levels of BDE-209 were twice as likely to have thyroid cancer. Those with high levels of TCEP dust were four times more likely to have large aggressive tumors.

Water Contamination May Trigger Thyroid Disease

Nearly 100 percent of people living in the U.S. have perchlorate in their body, but according to scientists, Arizona is one of the six most perchlorate-polluted states.13 As perchlorate remains stable in water, it may easily invade drinking water supplies. The chemical is known to disrupt health by preventing iodide uptake at the thyroid gland. Your thyroid gland requires iodide in order to produce thyroid hormone.14 Thus if the perchlorate prevents iodide uptake, it reduces the amount of thyroid hormones in your body.

Perchlorate may also slow brain development in infants. C. Loren Buck, Ph.D., of Northern Arizona University,15 will lead a two-year study to evaluate the effects of the chemical on citizens in Yuma, Arizona. The process for the biomolecular substitution of perchlorate for iodide is called the Finkelstein Reaction.16 This reaction is not limited to perchlorate in the thyroid gland, but also occurs with other additives found in city water, namely fluoride.17,18

A British study found a strong correlation between areas where fluoride content was highest with higher risk of developing underactive thyroid function. In fact, in areas where the levels of fluoride exceeded 0.3 milligrams per liter (mg/L) the risk of low thyroid function rose by 30 percent.19

In the U.S., the minimum standards for drinking water fluoridation are set at 0.7 mg/L by the U.S. Health and Human Services.20 This means the risk of low thyroid function as a result of poor iodide uptake may be even higher in Americans than those found in the British study, based on higher levels of fluoridation.

Natural Strategies to Support Your Thyroid Function

A diagnosis of suboptimal thyroid function is best made with a combination of blood testing and screening for clinical symptoms. Symptoms of low thyroid function may include:

Unexplained fatigue


Dry skin


Feeling cold

Brain fog

Unexplained weight gain

Low libido

Hair loss

There are several natural strategies you may consider to help support your thyroid function and improve your health. These include:

Water filtration

As I discuss in a previous article, “Why Filtering Your Water is a Necessity,” fluoride is not the only chemical polluting your drinking water. While filtering the whole house is important to prevent chlorine from evaporating or aerosolizing into the air, fluoride removal is most important in your drinking water.

Unfortunately, most tap water contains a vast array of disinfection byproducts, chemicals, radiation, heavy metals and even pharmaceutical drugs. Fluoride, which is still being added to many municipal water supplies, is yet another factor that can make the water you drink each day more harmful than healing.


An herb native to Asia and India, it has been a powerful tool in Ayurvedic medicine for thousands of years. It functions as an adaptogen, meaning it helps your body adapt to challenges by balancing your immune system, metabolism and hormonal systems.21

The root contains the highest concentration of the active ingredients in the plant and helps modulate hormone balances, including your thyroid hormone. It has also demonstrated positive effects on estrogen and progesterone balance as women move toward menopause.

The root reduces cortisol levels, restores insulin sensitivity and helps to stabilize your mood, even if depression isn’t part of your thyroid condition.22 Other research indicates it may protect your brain from oxidative stress and improve your energy level.23

Natural desiccated thyroid

Natural desiccated thyroid (NDT) is a prescription medication that may be referred to as natural thyroid, thyroid extract, or by the brand names Nature-Throid or Amour Thyroid.24 NDT contains T4, T3, calcium and other elements a natural thyroid gland would produce.

In a randomized, double-blind, crossover study, researchers compared NDT against levothyroxine in 70 patients, ages 18 to 65 years, who suffered from primary hypothyroidism.25 The patients took either medication for 16 weeks.

Afterward, patients were asked which they preferred and nearly 50 percent preferred the NDT versus 19 percent who preferred the levothyroxine. Those taking the NDT lost an average of 3 pounds while those taking the levothyroxine didn’t lose any weight.

Another study in the New England Journal of Medicine demonstrated a natural thyroid supplement was better at controlling mental functioning as it supplied both T3 and T4; T3 does 90 percent of the work of your thyroid hormones.26

If your doctor or endocrinologist will not consider switching you from levothyroxine to an NDT preparation, you may want to share this article and some of the available research with them, as a synthetic preparation is rarely the best choice to treat hypothyroidism.


This is a requirement for normal thyroid hormone function. In this video Dr. Jorge Flechas discusses the rampant iodine deficiency that plagues industrialized nations and the doses that may be necessary to reverse this trend.

Avoid sources of bromine

Bromine appears to play a large role in the rising number of people suffering from iodine insufficiency. Bromines are found in pesticides, plastics, baked goods, soft drinks and fire retardants.

Vitamins and amino acids

Vitamins B1227 and A28 with amino acid tyrosine29 have demonstrated beneficial effects in people who suffer from suboptimal thyroid function.


This is an extract of the sap from an Indian myrrh tree, which enhances the conversion of T4 to T3 in your body.30 Traditionally, the supplement was used to treat low metabolism, a symptom of suboptimal thyroid function. In an animal model, researchers found rats given guggul had increased uptake of iodine from their food and increased activity of thyroid enzymes with increased oxygen consumption.31

The supplement also demonstrated increased blood concentration of T3 hormone from T4 conversion,32 and increased the activity of the enzyme responsible for converting T4 to T3.33 It is likely unsafe during pregnancy and you should thoroughly evaluate the interactions with your physician before using it.34

Korean ginseng

This is an adaptogen like ashwagandha and contains properties that block production of excessive amounts of reverse T3 (rT3). Asian practitioners developed a fermented ginseng preparation that was absorbed better, faster and stayed in your body longer.35

A human study looked at the impact of this preparation on thyroid hormone levels and found that treatment by injection resulted in better clinical outcomes, healthy increase of T3 and T4 levels and a reduction in rT3.36


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