Postpartum thyroiditis

Postpartum thyroiditis
Postpartum thyroiditis
Specialty	Obstetrics

Last updated July 11, 2022

Postpartum thyroiditis refers to thyroid dysfunction occurring in the first 12 months after pregnancy ^[1] and may involve hyperthyroidism, hypothyroidism or the two sequentially. According to the National Institute of Health, postpartum thyroiditis affects about 8% of pregnancies.^[2] There are, however, different rates reported globally. This is likely due to the differing amounts of average postpartum follow times around the world, and due to humans' own innate differences. For example, in Bangkok, Thailand the rate is 1.1%, but in Brazil it is 13.3%.^[2] The first phase is typically hyperthyroidism. Then, the thyroid either returns to normal or a woman develops hypothyroidism. Of those women who experience hypothyroidism associated with postpartum thyroiditis, one in five will develop permanent hypothyroidism requiring lifelong treatment.

Postpartum thyroiditis is believed to result from the modifications to the immune system necessary in pregnancy, and histologically is a subacute lymphocytic thyroiditis. The process is normally self-limiting, but when conventional antibodies are found there is a high chance of this proceeding to permanent hypothyroidism. Postpartum thyroiditis is a member of the group of thyroiditis conditions known as resolving thyroiditis.

Signs and symptoms

The initial phase of hyperthyroid symptoms occurs transiently about two to six months postpartum.^[3] Typical symptoms include irritability, nervousness, palpitations, and heat intolerance. Hormonal disturbances during this phase tend to occur with lower intensity compared with the hypothyroid phase.^[3] As a result, the hyperthyroid phase may pass undetected. The second phase of hypothyroid symptoms is also transient and can occur anytime within the three- to twelve-month period postpartum.^[3] Women in this phase experience low energy, poor memory, impaired concentration, carelessness, dry skin, cold intolerance, and general aches and pains. After one year postpartum, euthyroid function resumes. Any case with hypothyroid symptoms extending beyond one year postpartum is not considered postpartum thyroiditis.^[3]

Women who test positive for thyroid antibodies may be at increased risk of developing symptoms associated with postpartum depression than women without thyroid antibodies.^[4]

Cause

During pregnancy, immunologic suppression occurs which induces tolerance to the presence of the fetus.^[5] Without this suppression, the fetus would be rejected causing miscarriage.^[5] As a result, following delivery, the immune system rebounds causing levels of thyroids antibodies to rise in susceptible women.^[6]

Specifically, the immunohistological features of susceptible women are indicated by:^[5]

antibodies to thyroglobulin (TgAb)
antibodies to thyroid peroxidase (TPOAb)
increase in TPOAb subclasses IgG1-IgG3
lymphocyte infiltration and follicle formation within thyroid gland (Hashimoto's thyroiditis)
T-cell changes (increased CD4:CD8 ratio)
TSH-receptor antibodies (TSH-R Abs)

Diagnosis

This condition is commonly undiagnosed by physicians due to either unfamiliarity with the disease, the subtlety of symptoms, or the attribution of the symptoms to the stresses of having a newborn.^[6] Usual screening begins with assessing the thyroid stimulating hormone (TSH) level. A suppressed TSH could represent the hyperthyroid phase, but warrants further testing to investigate for possible Graves' disease.^[6] A normal TSH with persistent symptoms could represent the shift between phases and requires repeat testing 4–6 weeks later; an elevated TSH at this time could indicate the hypothyroid phase.^[6]

Treatment

For most women, the hyperthyroid phase presents with very mild symptoms or is asymptomatic; intervention is usually not required. If symptomatic cases require treatment, a short course of beta-blockers would be effective.^[3]

Assessing treatment for the hypothyroid is more complex. Women with symptoms or a very high TSH level, or both, are usually prescribed a course of levothyroxine.^[3] Asymptomatic women with slightly elevated TSH levels who are planning subsequent pregnancies, should consider a course of treatment until completion of the family to avoid possible developmental complications in future children.^[3] Otherwise, treatment could be discontinued after one year postpartum.^{[ citation needed ]}

Prevalence

Women with type I diabetes mellitus have a threefold increase in the prevalence of postpartum thyroiditis than non-diabetic women in the same region.^[3]

According to Johns Hopkins, 3 in 100 women develop postpartum thyroiditis. Some risk factors include antithyroid antibodies, type 1 diabetes, history of thyroid problems, and family history of thyroid problems. According to the National Institute of Health, postpartum thyroiditis is especially common in Pakistan because it is an iodine-deficient country.^{[ citation needed ]}

Related Research Articles

Hyperthyroidism Thyroid gland disease that involves an overproduction of thyroid hormone.

Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormones by the thyroid gland. Thyrotoxicosis is the condition that occurs due to excessive thyroid hormone of any cause and therefore includes hyperthyroidism. It is noted that thyrotoxicosis is related to hyper-kinetic movement disorders including chorea and myoclonus. Some, however, use the terms interchangeably. Signs and symptoms vary between people and may include irritability, muscle weakness, sleeping problems, a fast heartbeat, heat intolerance, diarrhea, enlargement of the thyroid, hand tremor, and weight loss. Symptoms are typically less severe in the elderly and during pregnancy. 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. The opposite is hypothyroidism, when the thyroid gland does not make enough thyroid hormone.

The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The thyroid is located at the front of the neck, below the Adam's apple. Microscopically, the functional unit of the thyroid gland is the spherical thyroid follicle, lined with follicular cells (thyrocytes), and occasional parafollicular cells that surround a lumen containing colloid. The thyroid gland secretes three hormones: the two thyroid hormones – triiodothyronine (T₃) and thyroxine (T₄) – and a peptide hormone, calcitonin. The thyroid hormones influence the metabolic rate and protein synthesis, and in children, growth and development. Calcitonin plays a role in calcium homeostasis. Secretion of the two thyroid hormones is regulated by thyroid-stimulating hormone (TSH), which is secreted from the anterior pituitary gland. TSH is regulated by thyrotropin-releasing hormone (TRH), which is produced by the hypothalamus.

Graves disease Autoimmune endocrine disease

Graves' disease, also known as toxic diffuse goiter, is an autoimmune disease that affects the thyroid. It frequently results in and is the most common cause of hyperthyroidism. It also often results in an enlarged thyroid. Signs and symptoms of hyperthyroidism may include irritability, muscle weakness, sleeping problems, a fast heartbeat, poor tolerance of heat, diarrhea and unintentional weight loss. Other symptoms may include thickening of the skin on the shins, known as pretibial myxedema, and eye bulging, a condition caused by Graves' ophthalmopathy. About 25 to 80% of people with the condition develop eye problems.

Hypothyroidism is a 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, constipation, slow heart rate, depression, and weight gain. Occasionally there may be swelling of the front part of the neck due to goiter. Untreated cases of hypothyroidism during pregnancy can lead to delays in growth and intellectual development in the baby or congenital iodine deficiency syndrome.

Thyroid-stimulating hormone (also known as thyrotropin, thyrotropic hormone, or abbreviated TSH) is a pituitary hormone that stimulates the thyroid gland to produce thyroxine (T₄), and then triiodothyronine (T₃) which stimulates the metabolism of almost every tissue in the body. It is a glycoprotein hormone produced by thyrotrope cells in the anterior pituitary gland, which regulates the endocrine function of the thyroid.

Myxedema is a term used synonymously with severe hypothyroidism. However, the term is also used to describe a dermatological change that can occur in hyperthyroidism and (rare) paradoxical cases of hypothyroidism. In this latter sense, myxedema refers to deposition of mucopolysaccharides in the dermis, which results in swelling of the affected area. One manifestation of myxedema occurring in the lower limb is pretibial myxedema, a hallmark of Graves disease, an autoimmune form of hyperthyroidism. Myxedema can also occur in Hashimoto thyroiditis and other long-standing forms of hypothyroidism.

Hashimoto's thyroiditis, also known as chronic lymphocytic thyroiditis and Hashimoto's disease, is an autoimmune disease in which the thyroid gland is gradually destroyed. Early on, symptoms may not be noticed. Over time, the thyroid may enlarge, forming a painless goiter. Some people eventually develop hypothyroidism with accompanying weight gain, fatigue, constipation, depression, hair loss, and general pains. After many years the thyroid typically shrinks in size. Potential complications include thyroid lymphoma. Furthermore, because it is common for untreated patients of Hashimoto's to develop hypothyroidism, further complications can include, but are not limited to, high cholesterol, heart disease, heart failure, high blood pressure, myxedema, and potential pregnancy problems.

Levothyroxine, also known as L-thyroxine, is a manufactured form of the thyroid hormone thyroxine (T₄). It is used to treat thyroid hormone deficiency (hypothyroidism), including Hashimoto's disease and a severe form known as myxedema coma. It may also be used to treat and prevent certain types of thyroid tumors. It is not indicated for weight loss. Levothyroxine is taken by mouth or given by intravenous injection. Maximum effect from a specific dose can take up to six weeks to occur.

Ord's thyroiditis is a common form of thyroiditis, an autoimmune disease where the body's own antibodies fight the cells of the thyroid.

Complications of pregnancy are health problems that are related to pregnancy. Complications that occur primarily during childbirth are termed obstetric labor complications, and problems that occur primarily after childbirth are termed puerperal disorders. Severe complications of pregnancy, childbirth, and the puerperium are present in 1.6% of mothers in the US, and in 1.5% of mothers in Canada. In the immediate postpartum period (puerperium), 87% to 94% of women report at least one health problem. Long-term health problems are reported by 31% of women.

Thyroid disease is a medical condition that affects the function of the thyroid gland. The thyroid gland is located at the front of the neck and produces thyroid hormones that travel through the blood to help regulate many other organs, meaning that it is an endocrine organ. These hormones normally act in the body to regulate energy use, infant development, and childhood development.

Thyroiditis is the inflammation of the thyroid gland. The thyroid gland is located on the front of the neck below the laryngeal prominence, and makes hormones that control metabolism.

De Quervain's thyroiditis, also known as subacute granulomatous thyroiditis or giant cell thyroiditis, is a member of the group of thyroiditis conditions known as resolving thyroiditis. People of all ages and genders may be affected.

Subacute lymphocytic thyroiditis is a form of thyroiditis. Subacute lymphocytic thyroiditis may occur at any age and is more common in females. A variant of subacute lymphocytic thyroiditis occurs postpartum: postpartum thyroiditis. Both of these entities can be considered subtypes of Hashimoto's thyroiditis and have an autoimmune basis. Anti-thyroid antibodies are common in all three and the underlying histology is similar. This disorder should not be confused with de Quervain's thyroiditis which is another form of subacute thyroiditis.

The hypothalamic–pituitary–thyroid axis is part of the neuroendocrine system responsible for the regulation of metabolism and also responds to stress.

Autoimmune thyroiditis, is a chronic disease in which the body interprets the thyroid glands and its hormone products T3, T4 and TSH as threats, therefore producing special antibodies that target the thyroid's cells, thereby destroying it. It may present with hypothyroidism or hyperthyroidism and with or without a goiter.

Thyroid disease in pregnancy can affect the health of the mother as well as the child before and after delivery. Thyroid disorders are prevalent in women of child-bearing age and for this reason commonly present as a pre-existing disease in pregnancy, or after childbirth. Uncorrected thyroid dysfunction in pregnancy has adverse effects on fetal and maternal well-being. The deleterious effects of thyroid dysfunction can also extend beyond pregnancy and delivery to affect neurointellectual development in the early life of the child. Due to an increase in thyroxine binding globulin, an increase in placental type 3 deioidinase and the placental transfer of maternal thyroxine to the fetus, the demand for thyroid hormones is increased during pregnancy. The necessary increase in thyroid hormone production is facilitated by high human chorionic gonadotropin (hCG) concentrations, which bind the TSH receptor and stimulate the maternal thyroid to increase maternal thyroid hormone concentrations by roughly 50%. If the necessary increase in thyroid function cannot be met, this may cause a previously unnoticed (mild) thyroid disorder to worsen and become evident as gestational thyroid disease. Currently, there is not enough evidence to suggest that screening for thyroid dysfunction is beneficial, especially since treatment thyroid hormone supplementation may come with a risk of overtreatment. After women give birth, about 5% develop postpartum thyroiditis which can occur up to nine months afterwards. This is characterized by a short period of hyperthyroidism followed by a period of hypothyroidism; 20–40% remain permanently hypothyroid.

Antithyroid autoantibodies (or simply antithyroid antibodies) are autoantibodies targeted against one or more components on the thyroid. The most clinically relevant anti-thyroid autoantibodies are anti-thyroid peroxidase antibodies (anti-TPO antibodies, TPOAb), thyrotropin receptor antibodies (TRAb) and thyroglobulin antibodies (TgAb). TRAb's are subdivided into activating, blocking and neutral antibodies, depending on their effect on the TSH receptor. Anti-sodium/iodide (Anti–Na⁺/I⁻) symporter antibodies are a more recent discovery and their clinical relevance is still unknown. Graves' disease and Hashimoto's thyroiditis are commonly associated with the presence of anti-thyroid autoantibodies. Although there is overlap, anti-TPO antibodies are most commonly associated with Hashimoto's thyroiditis and activating TRAb's are most commonly associated with Graves' disease. Thyroid microsomal antibodies were a group of anti-thyroid antibodies; they were renamed after the identification of their target antigen (TPO).

Thyroid's secretory capacity is the maximum stimulated amount of thyroxine that the thyroid can produce in a given time-unit.

Thyroid disease in women is an autoimmune disease that affects the thyroid in women. This condition can have a profound effect during pregnancy and on the child. It also is called Hashimoto's thyroiditis (theye-royd-EYET-uhss). During pregnancy, the infant may be seriously affected and have a variety of birth defects. Many women with Hashimoto's disease develop an underactive thyroid. They may have mild or no symptoms at first, but symptoms tend to worsen over time. If a woman is pregnant and has symptoms of Hashimoto's disease, the clinician will do an exam and order one or more tests.

References

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1 2 Keely, Erin Joanne (March 2011). "Postpartum thyroiditis: an autoimmune thyroid disorder which predicts future thyroid health". Obstetric Medicine. 4 (1): 7–11. doi:10.1258/om.2010.100041. ISSN 1753-495X. PMC 4989649 . PMID 27579088.
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↑ Bokhari, R.; Bhatara, V.S.; Bandettini, F.; McMillan, J.M. (1998). "Postpartum psychosis and postpartum thyroiditis". Psychoneuroendocrinology. 23 (6): 643–650. doi:10.1016/S0306-4530(98)00034-1. PMID 9802134. S2CID 28530447.
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