You likely know that many of the synthetic chemicals in our environment can disrupt our hormones. While we tend to associate “hormones” with puberty or sex, they actually modulate everything from mood and appetite to immunity and metabolism.
Our endocrine system is a series of glands that releases hormones, but certain chemicals and genetic conditions can disrupt it. When our hormones are out of balance, our bodies can’t function optimally.
One of the most common types of endocrine disruption causes thyroid issues. Despite more than 200 million Americans having a thyroid disorder, it is notoriously under-diagnosed. Why, especially when they can seriously impair one’s health and happiness?
How Your Thyroid Works
First, let’s explore this vital organ and how it affects the rest of your body. The thyroid is a relatively small, butterfly-shaped gland at the front of your neck. Its hormone regulates the metabolism of cells throughout your body. That, in turn, affects your energy level, your muscles’ ability to generate force, your digestion, your immunity, and even your heart rate.
Thyroid cells work by converting iodine from your food into two types of hormones: thyroxine (T4) and triiodothyronine (T3). T3 and T4 travel through your bloodstream to modulate cellular metabolism in every major body system. Obviously, low levels of either T3 or T4 cause metabolism to slow down. This is called hypothyroidism (“hypo-” means “under”) and contributes to fatigue, depression, and weight gain.
On the flip side, too much T3 or T4 is called hyperthyroidism (“hyper” meaning “over”), and it essentially kicks your systems into overdrive. Symptoms include irritability, weight loss, and sleep disorders.
Here’s where it gets tricky. The thyroid itself depends on another gland, the pituitary gland, to stimulate its activity. This aptly named Thyroid-Stimulating Hormone (TSH) is a bit like a thermostat: when your T3 or T4 levels drop, the pituitary gland sends a message to the thyroid to turn on. When they’re too high, it stops producing TSH.
When checking your thyroid health, most doctors order a TSH test. They assume that if TSH is normal, the thyroid itself will be.
Unfortunately, that’s not always true.
What Causes Thyroid Disorders?
Inadequate or Excessive Iodine Intake
As the thyroid depends on iodine to produce T3 and T4, an iodine deficiency can certainly contribute to hypothyroidism. In such cases, the pituitary gland works overtime, causing the thyroid to enlarge in a condition called goiter. That’s more common in developing countries, though, where iodine is depleted. We mostly obtain iodine from certain vegetables that absorb it from the soil, as well as seafood. Mountainous regions and those with extensive mono-cropping tend to have iodine-deprived soil.
Too much iodine causes hyperthyroidism and can increase your risk of thyroid cancer. This typically isn’t a problem unless you pour tons of salt on your food (which is admittedly a problem in the U.S.) and/or take iodine supplements as well.
Assuming that dietary iodine isn’t an issue, thyroid disorders can be caused by autoimmune disease. The two most common autoimmune thyroid disorders are Graves’ disease and Hashimoto’s thyroiditis, which cause hyperthyroidism and hypothyroidism, respectively.
Graves’ is the primary cause of hyperthyroidism in areas where iodine is plentiful. Women are 10 times more likely to develop Graves than men. In this autoimmune disease, the body’s immune cells attack the TSH receptors. This means the pituitary gland will keep plugging away, sending errant messages to make more T3 and T4 even though there is already enough.
In Hashimoto’s, the immune system directly attacks the thyroid, preventing it from creating enough T3 and T4. The pituitary gland’s signals will go ignored. Also, the initial inflammatory response provokes a state of hyperactivity, which means people with Hashimoto’s may have both hyper- and hypothyroid symptoms.
In either condition, adjusting your iodine intake may not fix the issue. Unfortunately, it’s not clear what causes these autoimmune disorders. They’re typically treated with supplemental thyroid hormones.
Why Are Thyroid Disorders Hard to Diagnose?
Thyroid Disorders and Gender Bias
It’s worth noting that thyroid problems are 5-8 times more likely to affect women than men. As the medical community has an unfortunate tendency to dismiss women’s concerns as “stress,” this means that thyroid disorders often go undiagnosed. Worse, iodine deficiency is much likelier during pregnancy and can lead to severe birth defects.
Also, many symptoms of thyroid disorders, especially fatigue and mental illness, are common in other conditions. Due to prevailing sexist assumptions in medicine, physicians are often more likely to diagnose female patients with those conditions than with a thyroid disorder.
The problem is that all the antidepressants and weight-loss programs in the world won’t help if the thyroid is fundamentally impaired. Unfortunately, the medical community has yet to even agree on a “normal” level for T3, T4, or TSH. Many are reluctant to perform advanced thyroid screening if a patient has “subclinical” disorder. But with 11% of all tested patients showing some sort of thyroid imbalance, why are we ignoring this issue?
Thyroid Testing Issues
The initial screening test for thyroid disorders is the TSH test, which, as mentioned, only measures the amount of TSH produced by the pituitary gland. The problem is (a) those levels may be normal but an autoimmune response or toxin is directly impairing the thyroid, or (b) an overactive thyroid confuses the pituitary, suppressing TSH.
The “normal” range for TSH is 0.4-4.0 mIU/L of blood, If you fall within that broad range, most physicians won’t proceed with further testing. However, everything from what you ate that day to how much sleep you got can affect your levels. Many endocrine specialists now recommend that the normal range be changed to 0.4 to 2.5 mIU/L. If you suspect hyperthyroidism and your test result was marked “normal” because it was 3.0 mIU/L, you should ask for further testing.
Once we start measuring the actual T3 and T4 levels, it gets even more complicated. These are the tests of how much thyroid hormone is being produced. Ideally, you have 100-200 ng/dL of T3 and 5-12 μg/dL of T4. There’s also a “Free T4” that assesses the amount of T4 actually moving throughout your body, and it’s generally about 0.8-1.8 ng/dL.
All those numbers are just that, though: numbers. They can and do vary throughout the day depending on your diet and activity level. That’s why you must advocate for yourself to perform multiple tests along with close monitoring of your symptoms.
Differences in T3 vs T4 Deficiency or Hyperactivity
The thyroid mostly produces T4, which regulates your metabolism, body temperature, and mood. T3 makes up only 20% of your thyroid’s output but is much more potent, with significant effects on digestion. Some people have high T3 if not T4, which is linked to hyperthyroidism. Other cases of hyperthyroidism are indicated by too much T4 but a low TSH.
Meanwhile, low T4 can point to thyroid disease. If the TSH level is normal or high while T4 is low, that’s often a sign that the thyroid is impaired. On the flip side, low T4 and low TSH often points to trouble with the pituitary gland.
And to make things even more complicated, the thyroid itself may technically be fine, but your immune system attacks it by mistake, impairing its function. These autoimmune disorders can be detected by testing the level of thyroid antibodies in the blood.
In short, testing for thyroid disorders is complicated!
Common Thyroid Disorder Symptoms
Hypothyroidism, whether due to low iodine intake, Hashimoto’s, or other factors, typically causes:
- Fatigue and lethargy
- Always feeling cold
- Slow metabolism and consequent weight gain
- Memory and focus issues
- Dry skin and brittle nails
- Hair loss
- Joint pain and stiffness
- Excessive or prolonged menstrual periods
Hypothyroidism shares a lot of symptoms with depression, ADHD, iron or B12 deficiency, all of which can also exacerbate thyroid disorders. That’s why it’s crucial to perform multiple tests and evaluate your overall lifestyle and occurrence of symptoms.
Hyperthyroidism, whether due to high iodine levels, Graves’, or other factors, typically causes:
- Anxiety and nervousness
- Frequent sweating and feelings of being overheated
- Rapid or excessive weight loss
- Irritability or manic behavior
- Trouble sleeping
- Irritable bowel syndrome
- Hair loss
- Irregular or missed periods
Hyperthyroidism may initially appear to be an anxiety disorder, manic depression, or sleep disorder. Again, detailed testing and careful lifestyle monitoring are necessary to get answers.
Chemicals’ Effects on the Thyroid
As you know, synthetic chemicals can have harsh and cumulative effects on our bodies. Hormone disruption is a common symptom of toxin exposure, and your thyroid is no exception. Some of the best-known culprits for thyroid toxicity include:
- Octinoxate, commonly found in chemical sunscreens
- Perchlorate, which has leached into our soil and drinking water from industrial operations
- Polychlorinated biphenyls, or PCBs, banned lubricants and industrial additives that continue to linger in our environment
- Paraquat, a common herbicide, and benomyl and maneb/mancozeb, common fungicides
- Polybrominated diphenyl ethers (PBDEs), used as flame retardants in many electronics, furniture items, and synthetic blankets and towels
- Phthalates, which appear in everything from household cleaners to vinyl products to cosmetics
- PFOA, used in nonstick cookware, stain-resistant textiles, and some food packaging
- Bisphenol A (BPA), a key ingredient in many plastic containers for food and beverages
- Triclosan, a common antibacterial agent found in hand soap and sanitizer
Nutrition for Thyroid Health
As mentioned above, the thyroid depends on iodine. Notwithstanding any genetic or environmental factors, you can usually boost your thyroid by consuming iodine-rich foods, which include:
- Fish (especially cod, halibut, and tuna) and shellfish (especially shrimp, crab, and squid)
- Seaweed (kelp, nori, kombu, wakame)
- Dairy products
- Green leafy vegetables grown in iodine-rich soil
Adults should aim to consume about 150 mcg of iodine per day. Pregnant and breastfeeding people need much more — up to 290 mcg per day. Note that some foods contain goitrogens, so named because they contribute to goiter by impairing your iodine conversion. Common offenders include:
- Cruciferous vegetables (especially cabbage, Brussels sprouts, broccoli, cauliflower)
- Soy products (especially tofu and tempeh)
Obviously, those foods have plenty of health benefits, so we don’t recommend cutting them out completely. As always, a good balance is essential to a nutritious diet. Avoid overly salted, processed foods, and eat a nice mix of lean proteins and vitamin-rich vegetables. If you’re vegan or vegetarian, try to add iodine-fortified foods to make up for the lack of seafood and dairy.
For as important and delicate as the thyroid is, it’s disturbing that thyroid disorders are so widely underdiagnosed — especially when we are surrounded by toxic chemicals that can impair it. Your best chance at healthy thyroid function is to advocate for yourself. Don’t be afraid to ask for additional testing. Monitor your symptoms and adjust your diet and lifestyle accordingly. Thyroid disorders negatively affect almost every aspect of your well-being. With a bit of research and conscientious consumption, you can help protect this vital organ and ensure its optimal function.
This article was inspired by an interview with endocrine specialist and Hashimoto’s expert Dr. Gupta, author of Reversing Hashimoto’s.