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…
- mind fog
- goiter (enlarged thyroid gland)
- difficulty losing weight
- dry skin
- dry and/or thinning hair
- muscular weakness
- hoarse voice
- swollen joints
- irregular fertility cycle
- 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…
Foods to minimize with low thyroid function…
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 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…
- unintentional weight loss
- increased appetite
- heart palpitations
- elevated heart rate
- excess sweating
- fertility cycle irregularities
- dry skin
- dry or brittle hair
- lowered tolerance to heat
- increased frequency of bowel movements
- goiter (enlarged thyroid gland)
- muscle weakness
Some foods for support with elevated thyroid function…
Foods to minimize with elevated thyroid function…
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.
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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