A thyroid disease is a medical condition impairing the function of the thyroid. It is the most common endocrinopathy ever. Affects 10% of the adult population. Five times more common in women. The thyroid hormones act on nearly every cell in the body. Imbalance in production of thyroid hormones arises from dysfunction of the thyroid gland itself, the pituitary gland, which produces thyroid-stimulating hormone (TSH), or the hypothalamus, which regulates the pituitary gland via thyrotropin-releasing hormone (TRH). Concentrations of TSH increase with age, requiring age-corrected tests. Moreover, the thyroid gland continuously interacts with the ovaries, and the thyroid hormones are involved in almost all phases of reproduction. Thyroid dysfunctions are relatively common among women of reproductive age, and can affect fertility in various ways, resulting in anovulatory cycles, high prolactin levels, and sex hormone imbalances. Undiagnosed and untreated thyroid disease can be a cause of subfertility. Subclinical hypothyroidism (SCH), also known as mild thyroid failure, is diagnosed when peripheral thyroid hormone levels are within the normal reference laboratory range, but serum thyroid-stimulating hormone levels are mildly elevated. Thyroid autoimmunity (TAI) is characterized by the presence of anti-thyroid antibodies, which include anti-thyroperoxidase and anti-thyroglobulin antibodies. SCH and TAI may remain latent, asymptomatic, or even undiagnosed for an extended period. It has also been demonstrated that controlled ovarian hyperstimulation has a significant impact on thyroid function, particularly in women with TAI.

Thyroid disorders include:

it is a heterogeneous group of diseases

a) morphological changes (goiter - enlargement of the thyroid gland, thyroid tumor)
b) functional changes (hypothyreosis- abnormally decreased activity, hyperthyroidism - abnormally increased activity, autoimmune thyreopathy)

Autoimmune thyroid disease

The principal diseases of the human thyroid gland are goiter (diffuse or nodular), hyperthyroidism, hypothyroidism, autoimmune thyroiditis, and neoplasm. The thyroiditis types cause inflammation of thyroid tissue and can release preformed hormone from the colloid space, causing thyrotoxicosis, which is transient and followed by recovery or development of hypothyroidism. In acute and subacute thyroiditis, thyroid tenderness and neck pain are often present. On the other hand, silent thyroiditis is devoid of the local symptoms.

Hyperthyroidism 
Hyperthyroidism, also known as over active thyroid and hyperthyreosis, is the condition that occurs due to excessive production of thyroid hormone by the thyroid gland. Signs and symptoms vary between people and may include irritability, muscle weakness, sleeping problems, a fast heartbeat, poor tolerance of heat, diarrhea, enlargement of the thyroid, and weight loss. Symptoms are typically less in the old and during pregnancy. Hyperthyroidism occurs in about 0.2-0.4% of all pregnancies. Most cases are due to Graves’ disease although less common causes (e.g. toxic nodules and thyroiditis) may be seen. An uncommon complication is thyroid storm in which an event such as an infection results in worsening symptoms such as confusion and a high temperature and often results in death.

Hypothyroidism
Hypothyroidism, often called underactive thyroid or low thyroid and sometimes hypothyreosis, is a common disorder of the endocrine system in which the thyroid gland does not produce enough thyroid hormone. It can cause a number of symptoms, such as poor ability to tolerate cold, a feeling of tiredness, and weight gain. In children, hypothyroidism leads to delays in growth and intellectual development, which is called cretinism in severe cases. Hypothyroidism is common in pregnancy with an estimated prevalence of 2-3% and 0.3-0.5% for subclinical and overt hypothyroidism.

Thyroid cancers
In most cases, thyroid cancer presents as a painless mass in the neck. It is very unusual for thyroid cancers to present with symptoms, unless they have been neglected. One may be able to feel a hard nodule in the neck. Diagnosis is made using a needle biopsy and various radiological studies. Thyroidectomy and dissection of central neck compartment is initial step in treatment of thyroid cancer in majority of cases.

Associated diseases

Autoimmune thyroid disease
  • Autoimmune thyroiditis
Hyperthyroidism
  • congestive heart failure
  • coronary artery disease
  • Sjögren syndrome
  • rheumatoid arthritis
  • arthritis psoriatica
  • chronic periarthritis
  • Myasthenia gravis
  • diabetes mellitus
Hypothyroidism
  • depression
  • congestive Heart Failure
  • coronary Artery Disease
  • hyperlipidemia
  • Carpal Tunnel Syndrome
  • fibromyalgia
  • anemia
  • diabetes
  • myxedema
Thyroid cancers
  • swollen lymph nodes
  • diarrhea
  • cough
  • high blood pressure
  • hypothyroidism
  • Hashimoto's thyroiditis
  • thyroid nodules
Complications

Autoimmune thyroid disease
Common general complications include:
  • goiter
  • heart problems
  • mental health issues
  • birth defects
Hyperthyroidism
Common general complications include:
  • heart problems
  • britlle bones
  • eye problems
  • red, swollen skin
Hypothyroidism
  • goiter (a swelling of the neck or larynx resulting from enlargement of the thyroid gland (thyromegaly
  • heart problems
  • mental health issues
  • peripheral neuropathy (damage to or disease affecting nerves, which may impair sensation, movement, gland or organ function, or other aspects of health)
  • myxedema
  • infertility
  • birth defects
Thyroid cancers
      Spread of the cancer to the lungs, bones, or other parts of the body.
Risk factors

Autoimmune thyroid disease
  • smoking 
  • iodine excess 
  • family history of thyroid nodules
Hyperthyroidism
  • certain viral infections
  • pregnancy
  • a history of other autoimmune disorders
  • age
  • gender - women are more likely than men to develop hyperthyroidism
  • genetic factors - a family history of toxic diffuse goiter
  • other factors - start taking iodine supplements, this can increase your risk of hyperthyroidism
  • thyroid surgery
  • stress
  • smoking
  • diet 
Hypothyroidism 
  • a family history of thyroid dinase
  • autoimmune disorders (type 1 diabetes, rheumatoid arthritis)
  • thyroid surgery
  • exposed to radiation to your neck 
Thyroid cancers
  • gender and age
  • a diet low in iodine
  • radiation - exposure to ionizing radiation is a well-documented risk factor for cancer, the thyroid may be irradiated more than other tissues because of its position in the body and its ability to concentrate iodine

Male Infertility

The two most common types of thyroid diseases are hypothyroidism and hyperthyroidism. Studies assessing the role of hypo- and hyperthyroidism in male infertility have also been conducted in human subjects. Hypothyroidism may result in a decrease in the sex hormone binding globulin (SHBG) levels and a decrease in total serum testosterone levels, as well as a decrease in the LH and the follicle stimulating hormone (FSH) levels. In cases of prolonged pre-pubertal hypothyroidism due to drop in LH and FSH levels, the Leydig and Sertoli cells, respectively are less stimulated to differentiate into mature cells, negatively affecting spermatogenesis. This increases the number of cells in the testes but decreases the number of mature cells. Thus, in patients with hypothyroidism, increased testicular size is observed along with a significant drop in mature germ cells within the seminiferous tubules. 

Fortunately, hypothyroidism is very rare in males with an occurrence rate of only 0.1% in the general population. 

Hypothyroidism adversely affected semen quality by compromising semen volume and progressive sperm motility. 

It is therefore evident that hypothyroidism adversely affects male fertility. Similarly, all the studies on hyperthyroidism also reported adverse effects on male reproductive organs and fertility. Male infertility is more common than previously thought in males with hyperthyroidism, possibly in correlation with elevated levels of testosterone, LH, and FSH. Hyperthyroidism delays Leydig cell development and adversely affects spermatogenesis.

Female Infertility

Autoimmune thyroid diseases (AITD);  are the most common autoimmune conditions encountered in females in reproductive age characterized by presence of antibodies against to some structure of thyroid gland such as thyroglobulin (TG), thyroid peroxidase (TPO) and thyroid microsomale (TM). All AITD, to some extent, have implications for fertility and obstetrics. The presence of antithyroid antibodies may react against the structures of the placenta or fertilized egg and cause problems in embryo implantation. 

The older the woman, the higher the probability of anti-TPO antibodies. Anti-TPO antibodies increase with age.
Hypothyreoidism – negatively affects the rate of abortion, especially in the first trimester. Abortions occur 2 times more often. It also negatively affects sexual function such as decreased desire, increased pain in sex and also affects the orgasm of women.

Women with hypothyreosis often have oligomenorrhea, amenorrhea. Despite an increased prolactin, anovulation is present. Therefore, the menstrual cycle is completely affected.

Autoimmune thyroid disease

In regards to the prevention of autoimmune thyroiditis, there is no real access to adopt to avoid. People with personal or family history of autoimmune disease should also be controlled.

Hyperthyroidism

Naturally occurring hyperthyroidism cannot be prevented. Hyperthyroidism caused by taking too much thyroid drugs can be prevented. Periodically get blood tests to control thyroid levels.

Hypothyroidism

Hypothyroidism may be prevented in a population by adding iodine to commonly used foods. This public health measure has eliminated endemic childhood hypothyroidism in countries where it was once common.

Thyroid cancers

Number of people with thyroid caner do not have/display any known risk factors which makes it difficult to prevent it. Nevertheless, avoiding radiation exposure can significantly reduce the risk of development of cancer.

Autoimmune thyroid disease

The symptoms are often related to the stage of thyroiditis. There are many different signs and symptoms for thyroiditis, none of which are exclusively limited to this disease. Many of the signs imitate symptoms of other diseases, so thyroiditis can sometimes be difficult to diagnose. Common hypothyroid symptoms manifest when thyroid cell damage is slow and chronic, and may include fatigue, weight gain, feeling "fuzzy headed," depression, dry skin, and constipation. Other, rarer symptoms include swelling of the legs, vague aches and pains, decreased concentration and so on. When conditions become more severe, depending on the type of thyroiditis, one may start to see puffiness around the eyes, slowing of the heart rate, a drop in body temperature, or even incipient heart failure. On the other hand, if the thyroid cell damage is acute, the thyroid hormone within the gland leaks out into the bloodstream causing symptoms of thyrotoxicosis, which is similar to those of hyperthyroidism. These symptoms include weight loss, irritability, anxiety, insomnia, fast heart rate, and fatigue. Elevated levels of thyroid hormone in the bloodstream cause both conditions, but thyrotoxicosis is the term used with thyroiditis since the thyroid gland is not overactive, as in the case of hyperthyroidism.

Hyperthyroidism

Hyperthyroidism may be asymptomatic or present with significant symptoms. Some of the symptoms of hyperthyroidism include nervousness, irritability, increased perspiration, heart racing, hand tremors, anxiety, difficulty sleeping, thinning of the skin, fine brittle hair, and muscular weakness—especially in the upper arms and thighs.

Hypothyroidism

People with hypothyroidism often have no or only mild symptoms. Numerous symptoms and signs are associated with hypothyroidism, and can be related to the underlying cause, or a direct effect of having not enough thyroid hormones.

  • fatigue    
  • dry, coarse skin
  • feeling cold    
  • cool extremities
  • poor memory and concentration  
  • myxedema (mucopolysaccharide deposits in the skin)
  • constipation, dyspepsia    
  • hair loss
  • weight gain with poor appetite    
  • slow pulse rate
  • shortness of breath  
  • swelling of the limbs
  • hoarse voice    
  • delayed relaxation of tendon reflexes
  • in females, heavy menstrual periods (and later light periods)    
  • carpal tunnel syndrome
  • abnormal sensation
  • pleural effusion, ascites, pericardial effusion
  • poor hearing

Thyroid cancers

Most often the first symptom of thyroid cancer is a nodule in the thyroid region of the neck. However, many adults have small nodules in their thyroids, but typically under 5% of these nodules are found to be cancerous. Sometimes the first sign is an enlarged lymph node. Later symptoms that can be present are pain in the anterior region of the neck and changes in voice due to an involvement of the recurrent laryngeal nerve.

Yoga

Yoga normalizes the function of the thyroid, pituitary, pineal and adrenal glands by stimulating it.

Pharmacotherapy 

Levothyroxine is a stereoisomer of thyroxine which is degraded much slower and can be administered once daily in patients with hypothyroidism. Natural thyroid hormone from pigs is also used, especially for people who cannot tolerate the synthetic version. Graves' disease may be treated with the thioamide drugs propylthiouracil, carbimazole ormethimazole, or rarely with Lugol's solution. Hyperthyroidism as well as thyroid tumors may be treated with radioactive iodine. Percutaneous Ethanol Injections, PEI, for therapy of recurrent thyroid cysts and metastatic thyroid cancer lymph nodes is an alternative to the usual surgical method.

Surgical therapy

Thyroid surgery is performed for a variety of reasons. A nodule or lobe of the thyroid is sometimes removed for biopsy or for the presence of an autonomously function igadenoma causing hyperthyroidism. A large majority of the thyroid may be removed, a subtotal thyroidectomy, to treat the hyperthyroidism of Graves' disease, or to remove agoitre that is unsightly or impinges on vital structures.

A complete thyroidectomy of the entire thyroid, including associated lymph nodes, is the preferred treatment for thyroid cancer. Removal of the bulk of the thyroid gland usually produces hypothyroidism, unless the person takes thyroid hormone replacement. Consequently, individuals who have undergone a total thyroidectomy are typically placed on thyroid hormone replacement for the remainder of their lives. Higher than normal doses are often administered to prevent recurrence.

If the thyroid gland must be removed surgically, care must be taken to avoid damage to adjacent structures, the parathyroid glands and the recurrent laryngeal nerve. Both are susceptible to accidental removal and/or injury during thyroid surgery. The parathyroid glands produce parathyroid hormone (PTH), a hormone needed to maintain adequate amounts of calcium in the blood. Removal results in hypoparathyroidism and a need for supplemental calcium and vitamin D each day. In the event the blood supply to any one of the parathyroid glands is endangered through surgery, the parathyroid gland(s) involved may be re-implanted in surrounding muscle tissue. The recurrent laryngeal nerves provide motor control for all external muscles of the larynx except for the cricothyroid muscle, which also runs along the posterior thyroid. Accidental laceration of either of the two or both recurrent laryngeal nerves may cause paralysis of the vocal cords and their associated muscles, changing the voice quality.

Other therapies

Radioiodine therapy

Large goiters that cause symptoms but do not harbor cancer, after evaluation and biopsy of suspicious nodules, can be treated by an alternative therapy with radioiodine. The iodine uptake can be high in countries with iodine deficiency, but low in iodine sufficient countries. The 1999 release of recombinant human TSH, Thyrogen, in the USA, can boost the uptake to 50-60% allowing the therapy with Iodine 131. The gland shrinks by 50-60% but can cause hypothyroidism and rarely pain syndrome, which arises due to radiation thyroiditis. It is short lived and treated by steroids.

When treating infertility caused by thyroid disease, fertility treatment may be a effective option. This can be in the form of in-vitro fertilisation (IVF) depending on your conditions.

We recommend thyroid screening before IVF. In particular, thyroid stimulating hormone (TSH) and (thyroxine) fT4, as well as antibodies. The basic laboratory test for suspected thyroid dysfunction is the determination of thyroid stimulating hormone concentration in the blood.

If TSH is normal, thyroid malfunction may be excluded, with rare exceptions, and no further examination is needed. TSH elevations above 3.8-4.1 mIU / l have been shown in most cases for subclinical or fully developed hypothyroidism (decreased thyroid function). In some cases, serum concentration of the thyroid hormone (free thyroxine FT4) may also be added and we rarely investigate free trihydrate (FT3).

To explain the cause of hypothyroidism, serum concentrations of thyroid antibodies (more specific and more sensitive anti-thyroid TPOAb antibodies or less specific and sensitive anti-thyroglobulin antibodies - TgAb) and thyroid ultrasound are used. Thyroid antibody positivity is indicative of the autoimmune cause of hypothyroidism.

TSH decreased below 0.4 mIU / l (or 0.3-0.5 mIU / l according to the investigational method used). The causes of decreased (or suppressed) TSH may be more. In addition to increased thyroid gland activity (peripheral hyperthyroidism), central hypothyroidism (due to adenohypophysis) or suppression of TSH due to thyroid hormone treatment can be caused. To distinguish these causes, serum FT4 and FT3 should be investigated. Rather, in rare cases, the so-called TRH test is needed.

If hyperthyroidism (thyrotoxicosis, increased thyroid function) is confirmed in laboratory, its cause must be investigated. For this purpose, serum TSH receptor (TRAK) and thyroid ultrasound are tested in the first place. The TRAK positivity and a typical ultrasound finding are indicative of the autoimmune type of hyperthyroidism - Graves-Basedow's thyrotoxicosis.

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Sources

Hypothyroidism ―sourced from Wikipedia licensed under CC BY-SA 3.0
Hyperthyroidism ―sourced from Wikipedia licensed under CC BY-SA 3.0
THYROID ―sourced from World Heritage Encyclopedia licensed under CC BY-SA 3.0
Thyroid disease ―sourced from Wikipedia licensed under CC BY-SA 3.0
Autoimmune Thyroid Disorders ―by Iddah and Macharia licensed under CC BY 3.0
Thyroid disease in pregnancy ―sourced from Wikipedia licensed under CC BY-SA 3.0
Thyroid cancer ―sourced from Wikipedia licensed under CC BY-SA 3.0
Goitre ―sourced from Wikipedia licensed under CC BY-SA 3.0
Peripheral neuropathy ―sourced from Wikipedia licensed under CC BY-SA 3.0
Thyroid Function in Male Infertility ―by Krajewska-Kułak and Sengupta licensed under CC BY 4.0
Thyroid disorders and fertility ―by Karaca and Akpak licensed under CC BY-NC 4.0
Infertility ―sourced from Wikipedia licensed under CC BY-SA 3.0
Egg donation ―sourced from Wikipedia licensed under CC BY-SA 3.0
Assisted reproductive technology ―sourced from Wikipedia licensed under CC BY-SA 3.0
Radiation therapy ―sourced from Wikipedia licensed under CC BY-SA 3.0
Thyroiditis ―sourced from Wikipedia licensed under CC BY-SA 3.0
Thyroid scintigraphy ―by Perros licensed under CC BY-SA 3.0
Anterior thyroid ―by CFCF licensed under CC BY-SA 3.0
Thyoid-histology ―by Gille licensed under CC BY-SA 3.0
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