Get to Know Your Hypothalamus-Pituitary-Thyroid Axis

Your ability to maintain good health and equilibrium happens through a multitude of "axes" that connect throughout your body. Many of these axes are linked to your Hypothalamus and Pituitary glands in your brain. When an axis goes into imbalance, you may suffer any number of symptoms from fatigue and depression to unexplainable weight fluctuation and irregularities in fertility.

In this article, we will be focusing on the Hypothalamus-Pituitary-Thyroid Axis, or your HPT Axis. Thyroid imbalances are on the rise, particularly autoimmune-related thyroid dysfunction in which the immune system targets the thyroid gland.

An Introduction to the Thyroid Gland and the HPT Axis

The thyroid is a butterfly-shaped gland in the neck, located in front of the throat and just above the sternum.The thyroid makes thyroid hormone, without which we would die. Thyroid hormone travels throughout the body regulating growth and development, controlling how fast our cells burn energy, and influencing everything from nutrient absorption to heart rate to fertility. It influences these processes by binding to thyroid hormone receptors inside of cells.

The hypothalamus and pituitary gland in the brain regulate thyroid function via a “pass it down the line” approach. Basically, the hypothalamus tells the pituitary to tell the thyroid to make thyroid hormone.You may have heard of “TSH” (thyroid stimulating hormone) if you’ve had thyroid testing. TSH is how the pituitary tells the thyroid to make thyroid hormone.

As with the HPA axis, communication goes both ways along the HPT axis. Thyroid hormone talks back to the hypothalamus to regulate its own production by the thyroid. High levels of circulating thyroid hormone tell the hypothalamus that the body needs less of it. In response, the pituitary gland makes less TSH and the thyroid cuts back on hormone synthesis. Low levels of circulating thyroid hormone instead trigger a signal for increased production, with increased levels of TSH mediating this.

Thyroid hormone exists in different forms, including T4, T3 and reverse T3 (rT3). The thyroid produces mostly T4, which is inactive as a hormone, and small amounts of T3, which is active. Most T3 comes from conversion of T4 in various parts of the body. T4 is also converted into rT3, which binds to thyroid hormone receptors but doesn’t activate them like T3 does.

Iodine and thyroid function

Thyroid hormone contains iodine. The T4 form contains 4 iodine atoms. T3 and rT3 contain 3. The thyroid needs around 60 micrograms (mcg) of iodine daily to produce thyroid hormone.

Severe iodine deficiency is rare in Western countries, though there may be mild-to-moderate iodine deficiency, particularly in pregnant and breastfeeding women who have higher requirements for iodine. Also, certain chemicals can inhibit iodine uptake by the thyroid. These include bromate (a flour preservative), fluoride (a cavity preventer commonly found in drinking water), and chlorine (a disinfectant commonly found in drinking water, swimming pools, hot tubs, etc).

That said, there is a trend for supplementing with excessive amounts of iodine. Too much iodine can be a problem. In some folks, iodine excess causes overproduction of thyroid hormone (hyperthyroidism). In others, excess iodine may instead suppress thyroid hormone production. In rat studies, chronic high iodine intake increased incidence of autoimmune thyroid disease and in human population studies was associated with incidence of thyroid cancer.

The RDA for most adults is around 150 micrograms (mcg) daily. For pregnant or lactating women, it’s 220mcg and 290 mcg, respectively. While seaweeds from a clean area can be a good food-based source of iodine, be aware that iodine content can range widely. For instance, iodine content in kelp ranges from around a dozen mcg to over 8000 mcg. The American Thyroid Association recommends limiting intake of iodine from supplements and seaweeds to less than 500 mcg daily.

Hypothyroidism (Should this be an H3 for SEO?)

Hypothyroidism is when the thyroid doesn’t make enough thyroid hormone. It can happen if there’s an iodine deficiency or, sometimes, if there is a problem with the pituitary gland or hypothalamus. Autoimmune attack on the thyroid (Hashimoto’s disease) can also cause hypothyroidism.

Some signs of hypothyroidism include…

1. fatigue
2. mind fog
3. depression
4. goiter (enlarged thyroid gland)
5. difficulty losing weight
6. dry skin
7. dry and/or thinning hair
8. muscular weakness
9. constipation
10. cold-sensitivity
11. hoarse voice
12. swollen joints
13. irregular fertility cycle
14. slow pulse rate

Sometimes people have symptoms of hypothyroidism even if the thyroid is making proper levels of T4, or even when on thyroid medication that solely contains T4 (eg. levothyroxine). Why? Because sometimes conversion of the inactive T4 form of the hormone to T3 doesn’t happen sufficiently. Or, too much T4 is being converted into the inactive rT3. Either situation can result from: High stress, trauma, severe injury or illness, aging, alcoholism or other chronic chemical exposure or circumstances that influences liver health, kidney disease, type 2 diabetes, severe caloric restriction and other factors.

Foods for supporting thyroid function…

Salmon/cold water oily fish - Source of vitamin D and anti-inflammatory omega 3’s.

Selenium-rich foods - Support for conversion of T4 to T3. Brazil nuts, fish, lean meat, onions, garlic, chives, leeks, mushrooms, tomatoes, cooked cruciferous veggies, nutritional yeast, grass-fed butter.

Zinc-rich foods - Support conversion of T4 to T3. Pumpkin seeds, Brazil nuts, herring, poultry, lean red meat, cucumbers, peas, carrots, beets.

Iron-rich foods - Support for thyroid hormone production. Pair with vitamin C-rich foods for better iron uptake. Separate intake of iron-rich foods from thyroid medications by several hours. Salmon, shellfish, poultry, tomatoes, legumes, dark leafy greens, beets, prunes, figs.

Brightly colored produce - Antioxidant and anti-inflammatory support.

Foods to minimize with low thyroid function…

Soy - May decrease T3 levels. Regular intake may induce symptoms of low thyroid function.

Gluten - Inflammatory.

Refined foods in general - Inflammatory.

Raw cruciferous veggies - Contain “goitrogens” that suppress thyroid function. eg. Broccoli, Brussels sprouts, cauliflower, kale, radishes and others. Light steaming or other cooking methods will reduce goitrogen content.

Other goitrogen-containing foods can be found here.

Some herbs to support thyroid function…

It’s best to work with a trained practitioner for this. The thyroid can be tricky to work with and may swing back and forth between under- and over-active in some people. Also, don’t combine these herbs with thyroid medication unless working with a trained herbal practitioner and your prescribing doctor.

Milky Oat Tops (Avena sativa or Avena fatua) - Nourishing stress-reducing tonic that provide tyrosine, a building block of thyroid hormone.

Guggal (Commiphora mukul) - May promote the T4-to-T3 conversion.

Ashwagandha (Withania somnifera) - For proper immune system function. May increase T4. Stress support.

Blackseed (Nigella sativa) - May provide support with various aspects of Hashimoto’s

Hyperthyroidism

Hyperthyroidism is when too much thyroid hormone is produced. The thyroid may be inflamed and leaking excess thyroid hormone into circulation. Or, thyroid nodules may be present that overproduce thyroid hormone. Alternatively, the issue may be Grave’s disease, an autoimmune disorder where antibodies bind to and stimulate the thyroid. Another common reason for hyperthyroidism is over dosing with thyroid medication.

Some signs of hyperthyroidism…

1. unintentional weight loss
2. increased appetite
3. heart palpitations
4. elevated heart rate
5. insomnia
6. tremor/shakiness
7. restlessness
8. anxiety
9. excess sweating
10. fertility cycle irregularities
11. dry skin
12. dry or brittle hair
13. lowered tolerance to heat
14. increased frequency of bowel movements
15. goiter (enlarged thyroid gland)
16. fatigue
17. muscle weakness

Some foods for support with elevated thyroid function…

Raw cruciferous veggies - Contain chemicals that reduce iodine uptake by the thyroid.

Traditional forms of soy - Contain flavonoids that slow thyroid function. eg. Edamame, miso, tempeh, tamari. Soy contains certain flavonoids that impact thyroid function. Note! Please avoid: all processed forms such as soy milk, soy-based fake meats, textured vegetable protein, purified soy isoflavones.

Foods metabolized into thiocyanates - These are chemicals that reduce iodine uptake by the thyroid. Lima beans, flaxseed, sweet potatoes, sorghum.

Brightly colored produce - Antioxidant and anti-inflammatory support.

Foods to minimize with elevated thyroid function…

Dairy - High in iodine due to iodine-based utter disinfectants used prior to milking.

Commercial bread - May contain excessive amounts of iodine.

Gluten - May exacerbate autoimmune thyroid disease.

Refined foods in general - Inflammatory.

Herbal support with elevated thyroid function

Keep in mind that hyperthyroidism can be severe and even life threatening. Work with a trained herbal practitioner and see your doctor immediately if you are having strong symptoms of an overactive thyroid. Because it’s harder to suppress a function in the body than it is to promote it herbally-speaking, a practitioner will usually have you switch up your thyroid herbs regularly to keep the body responding.

Bugleweed (Lycopus virginicus) and Gypsywort (Lycopus europaeus) - Long history of traditional use. May reduce thyroid symptoms by multiple mechanisms. Support for proper heart function.

Lemon Balm (Melissa officinalis) - May reduce thyroid symptoms by multiple mechanisms, including reduced T4 to T3 conversion. Has recently become popular with herbalists for the thyroid. Calms the heart.

Motherwort (Leonurus cardiaca) - May reduce thyroid symptoms by multiple mechanisms. Calms the heart (I personally use it for this and notice when I stop taking it.)

So there you are…the thyroid and HPT axis in a nutshell!

This information has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease. 

If you are pregnant, nursing, taking medication, or have a medical condition, consult your physician before using this product. 

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