In this article:
- What is hypothyroidism?
- Understanding autoimmune disease In women
- Genetics, age, hormones
The results are staggering: one in eight women will develop hypothyroidism in her lifetime. There is some debate among medical researchers as to why women are at higher risk for hypothyroidism. We know that genetics, illness, and environmental factors may cause a person to develop this condition. But why are women 10x more likely to have hypothyroidism than men? Let's take a look at some of the risk factors that increase the odds for women.
What is hypothyroidism?
Hypothyroidism, or underactive thyroid, is a condition where your body does not produce enough thyroid hormone. Thyroid hormones impact every cell in your body. The thyroid is responsible for producing hormones that regulate vital processes such as metabolism, growth and development, and body temperature. When you do not have enough thyroid hormone, your system slows down.
Hypothyroidism disproportionality affects women compared to men. More often than not, the subtle signs that indicate a thyroid issue are brushed off or diagnosed as signs of aging, depression, and menopause. When hypothyroidism is left untreated, it can cause debilitating symptoms and adverse effects on your overall health and well-being. With the right dose of thyroid replacement medication and lifestyle changes, hypothyroidism is a manageable condition.
Hypothyroidism can be subclinical, which means your thyroid hormone levels are normal, but your thyroid-stimulating hormone (TSH) is mildly elevated. Some estimates suggest that between 3-8% of the population has subclinical hypothyroidism. Among this group, nearly 30% will develop primary hypothyroidism.
Understanding autoimmune disease in women
Women account for nearly 79% of people with autoimmune conditions. An autoimmune disease is where your body's immune system attacks its tissues. Usually, the immune system protects your body against foreign invaders such as bacteria and viruses by sending out proteins called antibodies. Sometimes, your immune system can become overactive or overly sensitive and attack your organs, including the thyroid gland.
The leading cause of hypothyroidism in the developed countries is the autoimmune disease Hashimoto's thyroiditis. In this disease, the thyroid gland is attacked by thyroperoxidase antibodies (TPO antibodies), resulting in chronic inflammation and eventual hypothyroidism.
There is much speculation as to why nearly 8 in 10 people with autoimmune diseases are female. In general, women's immune systems are better at responding to vaccines, infections, and trauma than men. They produce more antibodies. Men usually have more significant inflammation and increased mortality from infections. So, while women are better at fighting off infections, their more robust immune systems may turn against them by developing autoimmunity.
If you are curious about having hypothyroidism, specifically Hashimoto's, take a look at your close relatives. There is a strong genetic component to autoimmune diseases. One study found that first degree relatives of people with Hashimoto's have a nine times greater risk of developing Hashimoto's than the general population. Indeed, all autoimmune conditions tend to travel in families. Having one autoimmune disease increases your odds of polyautoimmunity, meaning you have multiple autoimmune conditions.
Hypothyroidism is commonly diagnosed in middle-aged women, although it occurs throughout the lifespan. Some studies find that hypothyroidism increases with age and often goes undiagnosed in older adults ages 65 and older.
In contrast to younger people where the symptoms are more visible, hypothyroidism is often missed because the symptoms are similar in age-related changes and illnesses. For example, constipation, fatigue, depression, and slow heart rate are often first considered changes related to age as opposed to declining thyroid function.
Aside from differences in immune function, the most apparent difference between men and women is in sex hormones. Estrogen plays a direct and indirect role in thyroid hormone production and availability in the body.
We know that estrogen increases the liver protein thyroxine-binding globulin (TBG), which binds to free thyroxine (T4) in your body. When TBG increases, there is less free T4 for cellular use, which can cause symptoms of hypothyroidism. Estrogen receptors may also play a role in thyroid cancers.
There is a possible connection between menopause and an underactive thyroid. Menopause occurs when a woman stops menstruating and thus is no longer able to get pregnant naturally. When a woman reaches menopause, her ovaries are no longer functioning and produce only minimal estrogen. The average age of menopause is 51. However, women can enter menopause as early as their 30s through their early 60s. There are many similarities in symptoms between menopause and hypothyroidism, which can make you feel confused about what is going on in your body.
Women can also develop hypothyroidism in pregnancy and the postpartum period. During pregnancy, high HCG levels can increase thyroid hormone levels that then cause a decrease in TSH. High estrogen levels may also impact the free thyroid hormone available for immediate use. Thyroid hormones are checked routinely during pregnancy. If hypothyroidism is detected, women must have treatment to prevent severe cognitive, neurological, and developmental defects at birth.
Postpartum thyroiditis is similar to Hashimoto's in that it is an autoimmune process characterized by the presence of TPO antibodies, anti-thyroglobulin, and thyroid inflammation. Women with a history of Hashimoto's, other autoimmune conditions, and a family history of thyroid disease are at higher risk for postpartum thyroiditis. Thyroiditis most commonly occurs in the first few months after delivery and then transitions to hypothyroidism within 4-8 months after birth. Many women regain their normal thyroid function, although 20% will continue to have hypothyroidism.
A note from Paloma Health
For women struggling with symptoms of hypothyroidism, it is essential to test your thyroid function. Sometimes these symptoms may be related to natural hormone changes such as in the menopause transition.