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Hormones are chemical messengers and a part of the body’s endocrine system.
Endocrine glands produce hormones which, then, travel through the bloodstream to tissues and organs to control or take part in many processes that occur in a human body.
Our body secretes more than 50 hormones and estrogen is one of them.
Estrogen is a vital hormone for our health and wellbeing, it participates in numerous functions which is why it is important to inspect its relationship with thyroid.
Role of estrogen
Estrogen is usually referred to as “female hormone”, but it is more than that.
The term estrogen is a group of chemically similar hormones such as estrone (E1), estradiol (E2), and estriol (E3). Although estrogen is considered a female hormone, men have it too in lower amounts.
According to Organic Lifestyle Magazine, in women, the greatest portion of estrogen is produced in the ovaries (although fat and adrenal glands produce some it too) “and other reproductive tissues. Since men lack this female anatomy, they produce estrogen through a process involving an enzyme aromatase which converts testosterone into estradiol.”
Before we discuss the relationship between estrogen and thyroid, it is important to understand the role of this hormone. Estrogen is vital for estrus cycle which influences female reproductive capacity.
The hormone has a wide array of effects on both reproductive system and the rest of your body. Estrogen regulates or influences the following functions:
- Estrogen increases fat storage around hips and thighs thus giving women more curved and contoured appearance
- In the brain, estrogen helps maintain body temperature, may delay memory loss, protects nerve cells from damage
- Estrogen is a significant factor in the maintenance of human skin through improved collagen quality and content, increased skin thickness, and enhanced blood supply to the skin
- Prevents bone loss
- May play a role in heart health
Relationship between estrogen and thyroid function
The idea that estrogen is associated with thyroid function comes after many studies showed that thyroid disorders are more prevalent in women than in men.
For example, the European Journal of Endocrinology published a study which analyzed data from 94,009 participants.
Findings revealed that the prevalence of formerly diagnosed hyperthyroidism was 2.5% in women and 0.6% in men while hypothyroidism affected 4.8% of ladies and 0.9% of males.
Based on these results, scientists concluded that thyroid dysfunction is more common in women than in men[i], although the risk of developing these health problems increases with age.
Research whose findings were published in the Clinical Endocrinology confirmed that women were more likely than men to develop both hyper- and hypothyroidism[ii].
On the other hand, a separate study showed that in overt immune hypothyroidism, 94.9% women and 91.3% of men reported at least one hypothyroidism-related symptom with dry skin, shortness of breath, and tiredness being the most common.
A growing body of evidence, like studies mentioned above, confirms that women are more susceptible to thyroid diseases than men, thus alluding to the role of estrogen. It is also important to mention that women are more prone to the goitrogenic effect of iodine deficiency, according to the study from the Journal of Clinical Endocrinology and Metabolism[iv].
When discussing the existence of the estrogen-thyroid relationship, it is necessary to mention the hormone indirectly contributes to thyroid economy by raising the thyroxine-binding globulin[v] (TBG), a type of globulin or protein produced in the liver.
The TBG is a circulating protein that reversibly binds thyroid hormones T3 and T4, and carries them into the bloodstream.
Estrogen receptors in thyroid tissue
Bearing in mind the link between estrogen and thyroid gland function, scientists started wondering if there are estrogen receptors in thyroid tissue.
At this point, studies show conflicting results, but it’s only due to limited research about this subject.
For example, a review of studies published in the Journal of Thyroid Research revealed that discovery of estrogen receptors (ER) in thyroid tissue dates back to 1981 and these receptors play a big role in tumors and carcinoma affecting the gland[vi].
On the other hand, a study from 2003 found that contrary to the earlier reports the ER is not detectable in thyroid tissues and the impact of estrogen on thyroid is more likely to be indirect[vii].
Furthermore, the Medical Science Monitor published a research that showed only ERβ receptors are found in thyroid tissue, but their expression doesn’t have significant specifications for differentiation between benign and malign lesions of the thyroid gland[viii].
One thing is for sure, we will have to wait for more studies on this subject in order to find out for sure whether estrogen receptors (both or just one) are expressed in thyroid tissue and their roles.
Estrogen dominance and hypothyroidism
Estrogen dominance is a condition that can affect both men and women and, as you can conclude by its name, it refers to the hormonal imbalance that occurs when there’s too much estrogen compared to other hormones in the body.
Your health and efficacy of a number of processes in your body depend on hormonal balance. In women, estrogen dominance occurs when the body has normal or excessive levels of this hormone and little to no progesterone.
Estrogen dominance is indicated by various symptoms including[ix]:
- Allergies, asthma, hives
- Breast tenderness and higher risk of breast cancer
- Cold hands or feet
- Dry eyes
- Enhanced symptoms of PMS
- Faster aging process
- Hair loss
- Increased risk or incidence of autoimmune conditions (including Hashimoto’s thyroiditis)
- Irregular menstrual periods
- Low libido
- Mood swings
- Sinus congestion
- Thyroid dysfunction
- Trouble sleeping
- Weight gain
Do any of the above-mentioned symptoms seem familiar? You’re right, some signs of estrogen dominance are also symptoms of hypothyroidism or underactive thyroid gland.
Hypothyroid patients experience symptoms such as weight gain, fatigue, hair loss, irritability or mood swings, low libido, and others.
This isn’t just some random coincidence; hypothyroidism is connected with estrogen dominance.
For example, a study from the journal Endocrine Research discovered that Hashimoto’s thyroiditis patients have a high prevalence of polycystic ovary syndrome. Hashimoto’s thyroiditis (HT) is an autoimmune condition and the most common cause of hypothyroidism.
Scientists also found that high incidence of polycystic ovary syndrome in HT patients is a result of increased estrogen to progesterone ratio which is directly involved in high anti-TPO (thyroid peroxidase antibody) levels[x].
Thyroid peroxidase is an enzyme from thyroid gland which plays an important role in the production of thyroid hormones.
Presence of TPO antibodies indicates that cause of thyroid disease is an autoimmune disorder, in this case, Hashimoto’s thyroiditis.
In hypothyroidism, particularly with an autoimmune component, the body isn’t able to detoxify estrogen properly.
As a result, estrogen levels accumulate, and the body contains an abnormal concentration of this hormone. This is when the estrogen dominance occurs.
Excessive estrogen levels block the function of the butterfly-shaped gland and contribute to the onset of hypothyroidism in more ways than one.
Too much estrogen inhibits the proteolytic enzymes (enzymes that digest protein) that allow your thyroid gland to produce hormones. As a result, the most important action of this gland decreases or stops.
At the same time, abnormally high levels of estrogen prevent the liver from converting T4 into T3 and they also slow down metabolism. When your metabolism is slow, the body is unable to use thyroid hormones efficiently.
Prolonged exposure to excessive estrogen leads to the above-mentioned rise of the anti-TPO antibodies which are linked to Hashimoto’s, which is also confirmed by a study from the Molecular and Cellular Endocrinology[xi].
Estrogen and hyperthyroidism
Evidence about estrogen and hyperthyroidism relationship is limited, but not nonexistent. A group of scientists from China discovered that increased expression of estrogen receptors is strongly associated with the development of Graves’ disease.
Graves’ disease is an autoimmune condition that is also known as one of the most common causes of hyperthyroidism, an overactive thyroid gland. Researchers also found that estrogen could be a promoting factor for Graves’ disease.
Differences in gender and age among patients who suffer from this autoimmune condition are related to the effects of estrogen on its receptors[xii].
Thyroid and menopause
If we bear in mind that estrogen is involved the relationship between estrogen and thyroid is evident, then it’s impossible not to wonder whether menopause and thyroid gland are also connected. During menopause, the function of ovaries stops which also decreases estrogen levels in the body.
Hypothyroidism can increase or aggravate symptoms associated with menopause. Evidence shows that ladies with a thyroid disorder and severe menopause-related symptoms, experienced tremendous relief after they received treatment for the problem with the thyroid gland[xiii].
Essentially, these findings indicate that menopausal women who experience severe symptoms should get their thyroid hormones checked and receive a treatment for underlying disorder in order to experience relief.
When discussing the relationship between thyroid and menopause, it is also useful to mention that hypothyroidism can contribute to the onset of complications associated with the “change”.
For instance, the most common complication of menopause is osteoporosis or loss of bone density and evidence shows that hypothyroidism can induce loss of bone density[xiv] too. The highest risk of this complication is among Caucasian women with low body fat.
In addition, menopause increases the risk of cardiovascular diseases and a growing body of evidence confirms that hypothyroidism can also raise the odds of developing heart diseases[xv] too.
Estrogen therapy and hypothyroidism
Low levels of estrogen associated with menopause are generally treated with estrogen therapy. As you already know, hypothyroidism also requires the use of hormone replacement in order to supply the body with thyroid hormone that this gland doesn’t produce sufficiently.
If you have some thyroid disorder and you’ve also entered menopause, the best thing to do is to consult your healthcare provider. Your doctor will inform you about the adequate treatment for declining levels of the much-needed hormone in a way it doesn’t affect hypothyroidism therapy.
A study from the journal Thyroid found that oral estrogen therapy increases T4 dosage requirements in hypothyroid women and it can also “alter thehttps://thyroidadvisor.com/know-thyroid-feedback-loop/ pituitary-thyroid axis in euthyroid” ladies.
On the other hand, transdermal estrogen therapy doesn’t “affect TBG levels” nor it alters thyroid function.
Based on these findings, scientists concluded that transdermal estrogen could be a “preferable modality for postmenopausal women who” also take T4 hormone[xvi]. Again, you should consult your doctor about the ideal treatment for your condition.
Estrogen is present in both female and in lower amounts in the male body, and it is a much-needed hormone for our health and wellbeing.
Women are more prone to thyroid disorders than men, and this only confirms the role of this hormone in the functioning of this gland. Studies show the impact of estrogen on thyroid is indirect but evident and meaningful. Estrogen dominance, a common problem, is also associated with Hashimoto’s thyroiditis and hypothyroidism.
The relationship between thyroid and estrogen is also indicated by the fact that hypothyroidism aggravates symptoms of menopause, which is characterized by low estrogen.
[i] Bjoro T, Holmen J, Kruger O, et al. Prevalence of thyroid disease, thyroid dysfunction, and thyroid peroxidase antibodies in a large, unselected population. The Health Study of Nord-Trondelag (HUNT). European Journal of Endocrinology 2000 Jun, 143, 639-647 http://www.eje-online.org/content/143/5/639.full.pdf
[ii] Vanderpump MPJ, Tunbrldge WMG, French JM, et al. The incidence of thyroid disorders in the community: a twenty-year follow-up of the Whickham Survey. Clinical Endocrinology 1995 Jul; 43(1):55-68. Doi: 10.1111/j.1365-2265.1995.tb01894.x http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2265.1995.tb01894.x/full
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[iv] Laurberg P, Pedersen KM, Hreidarsson A, et al. Iodine intake and the pattern of thyroid disorders: a comparative epidemiological study of thyroid abnormalities in the elderly in Iceland and in Jutland, Denmark. Journal of Clinical Endocrinology and Metabolism 1998 Mar;83(3):765-769. Doi: 10.1210/jcem.83.3.4624 https://academic.oup.com/jcem/article/83/3/765/2865144
[v] Ben-Rafael Z, Struass JF, Arendash-Durand B, et al. Changes in thyroid function tests and sex hormone binding globulin associated with treatment by gonadotropin. Fertility and Sterility 1987 Aug;48(2):318-320. Doi: 10.1016/S0015-0282(16)59363-7 http://europepmc.org/abstract/med/3111894
[vi] Santin AP, Weber Furlanetto T. Role of estrogen in thyroid function and growth regulation. Journal of Thyroid Research 2011 Feb. Doi: 10.4061/2011/875125 https://www.hindawi.com/journals/jtr/2011/875125/#B7
[vii] Arain SA, Shah MH, Meo SA, Jamal Q. Estrogen receptors in human thyroid gland: An immunohistochemical study. Saudi Medical Journal 2003 Feb;24(2):174-8 https://www.ncbi.nlm.nih.gov/pubmed/12682683
[x] Arduc A,Aycicek Dogan B, Bilmez S, et al. High prevalence of Hashimoto’s thyroiditis in patients with polycystic ovary syndrome: does the imbalance between estradiol and progesterone play a role? Endocrine Research 2015;40(4):204-10. Doi: 10.3109/07435800.1015730 https://www.ncbi.nlm.nih.gov/pubmed/25822940
[xi] Wang SH, Myc A, Koenig RJ, et al. 2-Methoxyestradiol, an endogenous estrogen metabolite, induces thyroid cell apoptosis. Molecular and Cellular Endocrinology 2000 Jul 25;165(1-2):163-72 https://www.ncbi.nlm.nih.gov/pubmed/10940494
[xiii] Badawy A, State O, Sherief S. Can thyroid dysfunction explicate severe menopausal symptoms? Journal of Obstetrics and Gynaecology 2007 Jul;27(5):503-5. Doi: 10.1080/01443610701405812 https://www.ncbi.nlm.nih.gov/pubmed/17701801
[xiv] Tuchendler D, Bolanowski M. The influence of thyroid dysfunction on bone metabolism. Thyroid Research 2014 Nov, 7(12). Doi: 10.1186/s13044-014-0012-0 https://thyroidresearchjournal.biomedcentral.com/articles/10.1186/s13044-014-0012-0
[xvi] Mazer NA. Interaction of estrogen therapy and thyroid hormone replacement in postmenopausal women. Thyroid 2004;14 Suppl 1:S27-34. Doi: 10.1089/105072504323024561 https://www.ncbi.nlm.nih.gov/pubmed/15142374