Postpartum thyroiditis is a type of thyroiditis,

inflammation Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', '' ...

of the

thyroid The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans, it is a butterfly-shaped gland located in the neck below the Adam's apple. It consists of two connected lobes. The lower two thirds of the lobes are connected by ...

, occurring in the first 12 months after

pregnancy Pregnancy is the time during which one or more offspring gestation, gestates inside a woman's uterus. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Conception (biology), Conception usually occurs ...

and typically involves

hyperthyroidism Hyperthyroidism is a endocrine disease in which the thyroid gland produces excessive amounts of thyroid hormones. Thyrotoxicosis is a condition that occurs due to elevated levels of thyroid hormones of any cause and therefore includes hyperth ...

followed by

hypothyroidism Hypothyroidism is an endocrine disease in which the thyroid gland does not produce enough thyroid hormones. It can cause a number of symptoms, such as cold intolerance, poor ability to tolerate cold, fatigue, extreme fatigue, muscle aches, co ...

which is most often temporary. Postpartum thyroiditis is believed to result from the modifications to the

immune system The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as Tumor immunology, cancer cells, Parasitic worm, parasitic ...

necessary in pregnancy, and histologically is the same as subacute lymphocytic thyroiditis also called silent thyroiditis or painless thyroiditis, a form of subacute thyroiditis. The process is normally self-limiting, but when thyroid antibodies are found there is a high chance of this proceeding to permanent hypothyroidism.

Signs and symptoms

The initial phase of hyperthyroid symptoms occurs transiently about two to six months postpartum. Typical symptoms include irritability, nervousness,

palpitations Palpitations occur when a person becomes aware of their heartbeat. The heartbeat may feel hard, fast, or uneven in their chest. Symptoms include a very fast or irregular heartbeat. Palpitations are a sensory symptom. They are often described as ...

, 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 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 perinatal depression, is a mood disorder which may be experienced by pregnant or postpartum women. Symptoms include extreme sadness, low energy, anxiety, crying episodes, irritability, and extreme cha ...

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 ...

(TgAb) * antibodies to

thyroid peroxidase Thyroid peroxidase, also called thyroperoxidase (TPO), thyroid specific peroxidase 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 ...

(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, Hashimoto's disease and autoimmune thyroiditis, is an autoimmune disease in which the thyroid gland is gradually destroyed. Early on, symptoms may not be noticed. Over ti ...

) * T-cell changes (increased

CD4 In molecular biology, CD4 (cluster of differentiation 4) is a glycoprotein that serves as a co-receptor for the T-cell receptor (TCR). CD4 is found on the surface of immune cells such as helper T cells, monocytes, macrophages, and dendritic c ...

CD8 CD8 (cluster of differentiation 8) is a transmembrane protein, 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 Cell signaling, signaling and aid ...

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 The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans, it is a butterfly-shaped gland located in the neck below the Adam's apple. It consists of two connected lobes. The lower two thirds of the lobes are connected by ...

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

Graves' disease Graves' disease, also known as toxic diffuse goiter or Basedow's disease, 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 thyro ...

. 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 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. 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.

Epidemiology

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

References

{{Pathology of pregnancy, childbirth and the puerperium Thyroid disease Pathology of pregnancy, childbirth and the puerperium