The thyroid, an essential gland that can suffer from pathologies
Thyroid, hypothyroidism, hyperthyroidism, TSH—these are words that can seem complicated. This article will shed light on the different elements you need to know about the thyroid and its disorders.
What is the thyroid?
The thyroid gland is a small, butterfly-shaped endocrine gland, weighing approximately 20g, located at the base of the neck. Among other things, it synthesizes thyroid hormones*, which control the body's basal metabolism. Thyroid hormones are therefore essential for regulating bodily functions and metabolism.
* What is a hormone? Hormones are chemical messengers produced by different organs in our body that act on cells in other organs. These cells have specific receptors for a particular type of hormone. There are many hormones in our body, and their regulation is finely tuned. Generally, a disruption in hormonal regulation leads to repercussions on the body's functions.
What is the role of the thyroid?
The thyroid is an endocrine gland. This means that it secretes hormones. The hormones secreted by the thyroid are T3, T4, and calcitonin.
The thyroid gland plays a role in modulating basal metabolism via T3 and T4. It contributes to maintaining body temperature, reflexes, growth, and muscle strength. The thyroid hormones T3 and T4 control basal metabolism, that is, resting energy expenditure. Resting energy expenditure is linked to maintaining vital functions; simply put, it's the energy expended relative to the body's minimum operating level, much like an engine idling.
The thyroid, through calcitonin, plays a role in calcium metabolism.
What are thyroid hormones?
Generally, when we talk about thyroid hormones, we're referring to T3 (triiodothyronine) and T4 (thyroxine). Thyroid hormones are produced from tyrosine and iodine. Iodine intake* is absolutely essential for thyroid function and is included in thyroid hormones. The thyroid primarily produces T4, which is then converted to T3 elsewhere in the body. T3 has greater activity than T4. T4 can be considered a mobilizable reserve form of thyroid hormones; deiodinases convert T4 to T3 to increase the amount of active hormones. There is also a form of thyroid hormone degradation called rT3 (reverse T3).
*FYI: Iodine allergy is a myth and does not exist. There are allergies to iodine-based products (e.g., povidone in Betadine), but not to iodine itself.
Calcitonin, less well-known, is a hormone that plays a role in calcium metabolism; it is balanced with PTH, which is secreted by the parathyroid glands.
The thyroid can malfunction
The thyroid, like any organ, can malfunction. Thyroid diseases vary in severity, but generally lead to changes in the secretion of thyroid hormones, which in turn impact the body's metabolism.
What is TSH?
The thyroid gland is controlled by the hypothalamic-pituitary axis. The hypothalamus, via TRH (tractive hormone hormone), triggers the pituitary gland to secrete TSH (thyroid-stimulating hormone). TSH controls thyroid metabolism and the production of thyroid hormones.
What are the main thyroid disorders?
The thyroid can be affected by various diseases:
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Graves' disease: an autoimmune disease that results in the development of hyperthyroidism
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Thyroid atrophy: this isn't really a disease, it's a process linked to aging. The thyroid gland loses volume and function, leading to hypothyroidism.
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Thyroiditis: these are inflammations of the thyroid that alter the synthesis of thyroid hormones.
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Hashimoto's thyroiditis, of autoimmune origin, which causes hypothyroidism
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De Quervain's thyroiditis (or subacute thyroiditis), of viral origin, causes pain, goiter and hyperthyroidism.
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Riedel's thyroiditis
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Parasitic thyroiditis (Chagas disease) caused by the trypanosome
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Goiter: it's more of a symptom than a disease. It's an increase, sometimes dramatic, in the size of the thyroid gland. It's found as a symptom in some thyroid diseases.
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thyroid cancer
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Nodules: they are common and vary in size. Nodules are grouped into subcategories.
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The secreting nodules: they cause hyperthyroidism
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non-secreting and harmless nodules
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Cancerous nodules are rarer. They are often large nodules that need to be removed.
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What are the symptoms of a thyroid that is not functioning properly?
Thyroid regulation problems, which cause over- or under-production of thyroid hormones, lead to multiple symptoms affecting several bodily functions. Whether it's hyperthyroidism or hypothyroidism, thyroid dysfunction impacts quality of life.
The main signs that reveal hypothyroidism
Hypothyroidism is linked to thyroid dysfunction. Hypothyroidism is a decrease in the amount of active thyroid hormones T3 and T4, below the body's needs. Hypothyroidism leads to decreased stimulation of various organs and is recognizable by the following symptoms:
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Hair and eyebrow loss
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Feeling cold, difficulty warming up
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Significant overall fatigue.
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Slower reflexes
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Muscle fatigue, low strength
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Feeling of shortness of breath
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Slowed intestinal transit, constipation
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Weight gain
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Hearing difficulties
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Lack of energy
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Absence, or near absence, of libido
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Increased cholesterol levels
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Concentration and memory problems
The main signs that reveal hyperthyroidism
Like hypothyroidism, hyperthyroidism is also caused by thyroid dysfunction. Hyperthyroidism is an increase in the amount of active thyroid hormones T3 and T4, above the body's needs. Hypothyroidism leads to decreased stimulation of various organs and is recognizable by the following symptoms:
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Feeling hot all the time
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Excessive sweating
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Mood disorders: excessive emotionality, mood swings
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Hyperactivity
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Weight loss
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Difficulty falling asleep and poor sleep quality
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Disrupted bowel movements: accelerated transit, diarrhea
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Feeling like you're always hungry
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Lack of muscle strength
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Tremors
What are the common causes of hyperthyroidism and hypothyroidism?
Various diseases can cause hyperthyroidism and hypothyroidism.
Causes of hypothyroidism:
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Thyroid atrophy
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Congenital hypothyroidism
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Thyroid removal (replacement therapy is usually offered)
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Incorrect dosage of replacement therapy (not enough levothyroxine)
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Hashimoto's disease
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A disruption in TSH secretion (decrease): this is central hypothyroidism
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Insufficient iodine intake
Causes of hyperthyroidism:
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Postpartum thyroiditis, which sometimes occurs after pregnancy
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Thyroid nodules
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Graves' disease
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De Quervain's viral thyroiditis
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Incorrect dosage of replacement therapy (too much levothyroxine)
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Medical treatment
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A disruption in TSH secretion (increase): this is central hyperthyroidism
Diagnosing thyroid disorders
If you have several symptoms suggestive of a thyroid disorder (goiter, signs of hyperthyroidism, signs of hypothyroidism), it is recommended that you consult a healthcare professional who can perform a clinical examination and prescribe tests to measure thyroid hormones and TSH levels. These medical tests will help refine the diagnosis and allow for the recommendation of appropriate treatment if necessary. In cases of severe hypothyroidism, hormone replacement therapy may be prescribed. These treatments are complex to implement, as it is often necessary to proceed by trial and error to find the ideal dosage that achieves euthyroidism.
Some endocrinologists also believe that too many people are put on replacement therapy when it is not necessary; depending on the case, lifestyle and dietary measures can restore a balance of thyroid hormones.
What is the role of TSH in thyroid disorders?
TSH ( thyroid-stimulating hormone ) or thyrotropin is secreted by the pituitary gland under the action of TRH ( thyrotropin-releasing hormone ) or thyrotropic hormone secreted by the hypothalamus.
TSH is measured in the blood during thyroid function tests. TSH helps control the production of thyroid hormones; its level rises to increase thyroid hormone production and falls to decrease it. Its secretion is a response to hormone levels (this is called negative feedback ). Quite simple...
TSH elevated
When TSH levels rise, it indicates insufficient production of T3 and T4 hormones. This is a telltale sign of hypothyroidism. Thyroid hormone levels are then measured to confirm the diagnosis.
More rarely, there may be a central origin to the increase in TSH, which in this case leads to hyperthyroidism.
TSH decreased
When TSH levels decrease, it indicates that the production of T3 and T4 hormones is excessive. This is a telltale sign of hyperthyroidism. A thyroid hormone test is then performed to confirm the diagnosis.
More rarely, there may be a central origin to the decrease in TSH, which in this case leads to hypothyroidism.
What nutrients are essential for thyroid function?
To function properly and synthesize thyroid hormones, the thyroid needs essential nutrients (see our article: " How to take care of your thyroid with diet? ") . Thyroid function, and therefore euthyroidism (the proper balance of thyroid hormones), is thus dependent on nutritional intake.
The two main nutrients essential for thyroid function are:
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Selenium is an integral part of the selenoproteins found in the thyroid gland. Selenium deficiencies have been shown to be linked to a number of thyroid disorders, and selenium supplementation has been shown to improve their status.
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Iodine is an essential component of thyroid hormones. Iodine intake is crucial, and a deficiency leads to decreased hormone production, resulting in subclinical hypothyroidism. Nutritional iodine deficiency also impacts fetal development during pregnancy, particularly brain development. Iodine deficiency is the origin of the term "cretinism in the Alps"; in the past, mountain dwellers were often iodine deficient, resulting in hypothyroidism and intellectual disability in children. Nowadays, salt is artificially iodized (it must be labeled "iodized salt") to ensure iodine intake for the entire population. Conversely, while iodine deficiency is detrimental to thyroid function, an excess is equally harmful and also causes hypothyroidism.
Other nutrients are also beneficial to thyroid function:
What foods should you eat to maintain your thyroid health?
Certain foods can be goitrogenic (they promote the development of a goiter) and should be avoided in excess if you have thyroid problems. These include, in particular, soy and cruciferous vegetables (cabbage, broccoli, cauliflower, Brussels sprouts).
To ensure an adequate intake of essential nutrients for thyroid function, it is best to consume foods that contain:
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iodine (iodized salt, seafood, fish, milk and dairy products...)
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Selenium (found in oily fish, seafood, eggs, Brazil nuts, whole grains, etc.)
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Tyrosine (found in cheeses, eggs, meats, cod, legumes, etc.)
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B vitamins (brewer's yeast, offal, legumes, eggs, cheeses, fish)
How to take care of your thyroid naturally?
In cases of thyroid disorders, it is beneficial to implement lifestyle and dietary measures.
Certain common foods and behaviors should be avoided:
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excessive coffee consumption
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excessive alcohol consumption
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excessive consumption of goitrogenic foods
It is important to prioritize the consumption of foods that contain nutrients essential to the thyroid, particularly iodine, selenium, and zinc.
Dietary supplements can also prove useful. Indeed, depending on their formulation, they can provide essential nutrients and utilize herbal remedies with regulatory properties, such as Guggul.
At Phytocea , we have created a special thyroid food supplement: Thyro. Thyro is a food supplement that provides a natural supply of iodine , selenium , tyrosine , zinc , and B vitamins . In Thyro, we have incorporated Guggul for its thyroid-regulating properties and its ability to facilitate iodine absorption.
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Sources
HAS guidelines for hypothyroidism
HAS guidelines for subclinical hypothyroidism
