Hashimoto's Disease

Definition - What does Hashimoto's Disease mean?

Hashimoto's disease is a condition in which a person's immune system starts attacking the body's own thyroid (a small butterfly-shaped gland that sits at the base of the neck below the Adam's apple). Consequently, the thyroid gland becomes underactive and makes less thyroid hormones. An imbalance in thyroid hormone secretion can cause infertility.

FertilitySmarts explains Hashimoto's Disease

The thyroid gland produces thyroid hormones that regulate various bodily functions. In cases of autoimmune attack of the thyroid gland (such as in Hashimoto's thyroiditis), antibodies damage the thyroid gland reducing the production of thyroid hormones.

What exactly incites this autoimmune attack is not clear. However, the following factors may boost the risk of developing autoimmune thyroiditis:

  • Sex: Women are much more likely to develop Hashimoto's disease
  • Age: Hashimoto's disease commonly occurs during middle age but can affect individuals at any age
  • Hereditary: A family history of thyroid or other autoimmune illness maximizes the risk for Hashimoto's disease
  • People having another autoimmune disease like rheumatoid arthritis or lupus —are more prone to Hashimoto's disease
  • Exposure to radiation

Hashimoto's disease may be asymptomatic and be detected on routine screening of thyroid function or it may present with signs and symptoms of an underactive thyroid (or hypothyroidism). These include:

  • Fatigue and loss of energy
  • Constipation
  • Unexplained weight gain
  • Pale, dry skin
  • Puffy face
  • Enlarged tongue
  • Enhanced sensitivity to cold
  • Hair loss
  • Muscle aches and joint pain and stiffness
  • Heavy menstrual bleeding (menorrhagia)
  • Depression
  • Memory loss
  • Sleep apnea and excessive daytime sleepiness
  • Infertility

Thyroid hormone secretion is under the control of a pituitary hormone called thyroid-stimulating hormone (TSH), which in turn is under the control of a hormone released from the hypothalamus called thyrotropin-releasing hormone (TRH). When the thyroid hormone levels drop, TSH and TRH blood levels go up. TRH stimulates the pituitary gland to activate another hormone called prolactin that subsequently interferes with ovulation, eventually leading to infertility.

The presence of thyroid antibodies in a pregnant woman poses a significant risk of miscarriage or preterm delivery even if the TSH value is within the normal trimester-specific range. Thyroid antibodies can be detected in 17-33% of pregnant women with repeated miscarriages. An increased demand for thyroid hormones during pregnancy could account for this association between thyroid autoimmunity and recurrent pregnancy loss.

The diagnosis is confirmed by detecting low thyroid hormones and raised TSH levels in the blood. In pregnant women, trimester-specific TSH levels are evaluated rather than one standard value. Presence of anti-thyroid peroxidase antibodies also allows for accurate diagnosis of autoimmune thyroiditis. The treatment involves replacing thyroid hormones with synthetic agents.

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