Postpartum thyroiditis refers to

thyroid 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 thy ...

dysfunction occurring in the first 12 months after

pregnancy Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but ca ...

and may involve

hyperthyroidism 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 ...

hypothyroidism Hypothyroidism (also called ''underactive thyroid'', ''low thyroid'' or ''hypothyreosis'') 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 po ...

or the two sequentially. According to the National Institute of Health, postpartum thyroiditis affects about 8% of pregnancies. 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%. The first phase is typically hyperthyroidism. Then, the

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 The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...

necessary in pregnancy, and histologically is a

subacute lymphocytic thyroiditis 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 ...

. The process is normally self-limiting, but when conventional

antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

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. Typical symptoms include irritability, nervousness,

palpitations Palpitations are perceived abnormalities of the heartbeat characterized by awareness of cardiac muscle contractions in the chest, which is further characterized by the hard, fast and/or irregular beatings of the heart. Symptoms include a rapi ...

, and heat intolerance. Hormonal disturbances during this phase tend to occur with lower intensity compared with the hypothyroid phase. 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. 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 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 thy ...

function resumes. Any case with hypothyroid symptoms extending beyond one year postpartum is not considered postpartum thyroiditis. Women who test positive for thyroid antibodies may be at increased risk of developing symptoms associated with

postpartum depression Postpartum depression (PPD), also called postnatal depression, is a type of mood disorder associated with childbirth, which can affect both sexes. Symptoms may include extreme sadness, low energy, anxiety, crying episodes, irritability, and chan ...

than women without thyroid antibodies.

Cause

During pregnancy, immunologic suppression occurs which induces tolerance to the presence of the fetus.Premawardhana, L.D.K.E., Parkes, A.B., & Lazarus, J.H. (2004). Thyroiditis, postpartum. In Editor-in-Chief: Luciano Martini (Ed.), ''Encyclopedia of endocrine diseases'' (pp. 509–514). New York: Elsevier. Without this suppression, the fetus would be rejected causing miscarriage. As a result, following delivery, the immune system rebounds causing levels of thyroids antibodies to rise in susceptible women.Stagnaro-Green, A. (2000). Recognizing, understanding, and treating postpartum thyroiditis. ''Endocrinology & Metabolism Clinics of North America'', 29(2), 417–430. Specifically, the immunohistological features of susceptible women are indicated by: * antibodies to

thyroglobulin Thyroglobulin (Tg) is a 660 kDa, dimeric glycoprotein produced by the follicular cells of the thyroid and used entirely within the thyroid gland. Tg is secreted and accumulated at hundreds of grams per litre in the extracellular compartment o ...

(TgAb) * antibodies to

thyroid peroxidase Thyroid peroxidase, also called thyroperoxidase (TPO) or iodide peroxidase, is an enzyme expressed mainly in the thyroid where it is secreted into colloid. Thyroid peroxidase oxidizes iodide ions to form iodine atoms for addition onto tyrosine re ...

(TPOAb) * increase in TPOAb subclasses IgG1-IgG3 * lymphocyte infiltration and follicle formation within thyroid gland (

Hashimoto's thyroiditis 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 enlarg ...

) * T-cell changes (increased CD4:

CD8 CD8 (cluster of differentiation 8) is a transmembrane glycoprotein that serves as a co-receptor for the T-cell receptor (TCR). Along with the TCR, the CD8 co-receptor plays a role in T cell signaling and aiding with cytotoxic T cell-antigen int ...

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. Usual screening begins with assessing the

thyroid stimulating hormone 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 ...

(TSH) level. A suppressed TSH could represent the hyperthyroid phase, but warrants further testing to investigate for possible

Graves' disease Graves' disease (german: Morbus Basedow), 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 thyr ...

. 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.

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 Beta blockers, also spelled β-blockers, are a class of medications that are predominantly used to manage abnormal heart rhythms, and to protect the heart from a second heart attack after a first heart attack (secondary prevention). They are al ...

would be effective. 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 Levothyroxine, also known as -thyroxine, is a manufactured form of the thyroid hormone thyroxine (T4). It is used to treat hypothyroidism, thyroid hormone deficiency (hypothyroidism), including a severe form known as myxedema coma. It may also ...

. 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. Otherwise, treatment could be discontinued after one year postpartum.

Prevalence

Women with

type I diabetes mellitus Type 1 diabetes (T1D), formerly known as juvenile diabetes, is an autoimmune disease that originates when cells that make insulin (beta cells) are destroyed by the immune system. Insulin is a hormone required for the cells to use blood sugar for ...

have a threefold increase in the prevalence of postpartum thyroiditis than non-diabetic women in the same region. According to

Johns Hopkins Johns Hopkins (May 19, 1795 – December 24, 1873) was an American merchant, investor, and philanthropist. Born on a plantation, he left his home to start a career at the age of 17, and settled in Baltimore, Maryland where he remained for most ...

, 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 The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late 1 ...

, postpartum thyroiditis is especially common in Pakistan because it is an iodine-deficient country.

Signs and symptoms

Cause

Diagnosis

Treatment

Prevalence

References

Further reading