Autoimmune thyroid diseases (AITDs) like Hashimoto’s and Grave’s disease are the most common organ-specific autoimmune disorders, affecting approximately 2–5% of the population. But the burden isn’t shared equally: women are five times more likely than men to develop Autoimmune thyroid diseases. Why the disparity?
This article explores why women are disproportionately affected by AITD and autoimmune diseases more broadly. We’ll cover:
- What the thyroid is and how it functions
- Key risk factors for developing Autoimmune thyroid diseases
- The role of hormones in autoimmune disease
- The link between PCOS and thyroid dysfunction
What Is the Thyroid?
The thyroid is a butterfly-shaped endocrine gland located in the lower front of the neck. It plays a central role in regulating metabolism, growth, and development by producing thyroid hormones and maintaining iodine balance in the body.
The gland primarily secretes two hormones:
- Thyroxine (T4) – the inactive form (about 90% of output)
- Triiodothyronine (T3) – the active form (about 10%), which is also produced by peripheral conversion of T4
T3 influences nearly every organ system by increasing metabolic rate and protein synthesis. The thyroid also contains parafollicular (C) cells, which produce calcitonin, a hormone that helps lower blood calcium levels and maintain calcium homeostasis by counteracting parathyroid hormone.
What Does the Thyroid Do?
The answer? Everything. Thyroid hormones affect virtually all nucleated cells in the body, enhancing their metabolic activity. Key effects include:
- Cardiovascular system: Increases heart rate, stroke volume, and cardiac output by enhancing calcium uptake in heart muscle cells. It also dilates blood vessels and activates the renin-angiotensin-aldosterone system, increasing blood volume.
- Metabolism and thermoregulation: Boosts basal metabolic rate, oxygen consumption, and heat production. This leads to increased glucose and fatty acid oxidation, thermogenesis, and heat dissipation—explaining heat intolerance in hyperthyroidism.
- Respiratory system: Elevates respiratory rate and ventilation to meet higher oxygen demands. T3 also stimulates erythropoietin and hemoglobin production, improving oxygen delivery.
- Skeletal system: Essential for fetal bone development and postnatal bone remodeling. It also breaks down extracellular matrix components like mucopolysaccharides (a type of sugar) .
- Nervous system: Enhances alertness, reflexes, and responsiveness. It also increases gastrointestinal tone and motility.
- Reproductive and endocrine systems: Regulates ovulation and spermatogenesis, modulates pituitary hormone release (stimulating growth hormone, inhibiting prolactin), and increases renal clearance of various substances.
What Causes Autoimmune thyroid diseases?
There’s no single cause of autoimmune thyroid disease—but researchers have identified a few key contributors:
- Genetics
- Epigenetics
- Environmental factors
While we can’t control our genes, environmental influences are where things get interesting: female sex hormones and pregnancy are consistently linked to increased AITD risk. While the exact hormonal culprit remains unclear, mounting evidence suggests that estrogen and other female hormones may modulate immune function in ways that predispose women to autoimmune disorders.
A study recently done on PCOS and thyroid function had some enlightening but grim findings.
PCOS and Thyroid Dysfunction
Women with PCOS tend to have:
- Elevated thyroid antibody levels
- Enlarged thyroid glands
- More hypoechogenic thyroid tissue (a marker of thyroiditis)
This suggests a higher prevalence of thyroid autoimmunity in PCOS patients. Interestingly, while hypothyroidism can lead to polycystic ovarian morphology, there’s no evidence that it causes PCOS itself.
So, are women with PCOS more prone to autoimmune disease? There’s a theoretical basis for this idea. PCOS is characterized by hyperestrogenism, and elevated estrogen levels have been proposed as a factor in the higher incidence of autoimmune conditions in women compared to men.
In short, women with PCOS could be at higher risk of autoimmune disease on top of the slew of other issues they already face. But it’s okay! Don’t get discouraged: we’ll keep making articles to support you through this journey. You can do this!
Wrapping up
For women navigating conditions like Autoimmune thyroid diseases or PCOS, knowledge is a powerful tool. It helps us ask better questions, advocate for ourselves, and push for research that reflects our realities.
While we don’t have all the answers yet, we’re getting closer. And every study, every conversation, every woman who shares her story brings us one step further. So if you’ve ever felt dismissed, confused, or alone in your health journey, know this: you’re not imagining things. You’re not alone. And your voice matters.
Let’s keep asking questions. Let’s keep pushing for answers. And let’s keep showing up—for ourselves and for each other.
Source
https://pmc.ncbi.nlm.nih.gov/articles/PMC4287775
