Hypothyroidism - How it Affects Women from Menstruation to Menopause

The thyroid plays a critical role in women’s health and hormones throughout the life cycle. The brain, thyroid, and ovaries (hypothalamic- pituitary- thyroid- gonadal, or HPTG, axis) work together to maintain healthy sex hormone levels (estrogen, progesterone, and testosterone). There is a close interplay between the thyroid and the ovaries.

The ovaries contain receptors for thyroid hormones and the thyroid contains receptors for estrogen and progesterone. This means that thyroid hormones (from the thyroid) are important for the health and functioning of the ovaries and estrogen and progesterone (from the ovaries) are important for the health and functioning of the thyroid. They are inextricably connected.

In fact, all aspects of reproductive function are dependent on optimal thyroid function. Poor thyroid function, such as in hypothyroidism (or an underactive thyroid), can have detrimental effects on menstrual cycles, fertility status, pregnancy outcomes, and the menopausal transition. Click here to learn more about hypothyroidism.

The more severe the hypothyroidism is, the more likely these problems are to occur and the worse they are likely to be. However, they can be fixed with treatment of hypothyroidism by replacement of thyroid hormones and/or interventions that reverse the disease process and restore thyroid function.

***In this blog, for simplicity, the term hypothyroidism will refer to overt hypothyroidism, Hashimoto’s disease, and subclinical hypothyroidism.***

Hypothyroidism & Menstruation

The thyroid helps regulate fluctuating sex hormone levels that control the menstrual cycle. Hypothyroidism can cause hormone imbalance and ovulatory dysfunction and thus menstrual irregularities including changes in cycle length and amount of bleeding.

Hypothyroidism can cause hormone imbalance:
- Hypothyroidism can cause low levels of all sex hormones. Alterations in hormone signals from the brain, including prolactin and gonadotropin-releasing hormone (GnRH), can prevent ovulation and even shut off the menstrual cycle entirely.
- Hypothyroidism can cause low progesterone levels, even after ovulation occurs (aka luteal defect/deficiency or LPD) by decreasing egg quality (healthy progesterone levels are important for supporting pregnancy). Lower AMH levels (an ovarian hormone important in egg development) and ovarian follicle counts indicate lower egg quality and quantity and have been found in women with hypothyroidism.
- Hypothyroidism can cause or contribute to estrogen dominance by inhibiting ovulation (decreasing progesterone), altering the metabolism of estrogen in the liver and gut (increasing estrogen), and decreasing sex hormone binding globulin (SHBG, increasing estrogen). Estrogen dominance can further disrupt the menstrual cycle by causing or worsening PMS, in addition to other associated health symptoms and risks - click here to learn more about estrogen dominance.
Hypothyroidism can cause anovulation:
- Hypothyroidism can prevent the mid-cycle release of a mature egg from an ovary (aka anovulation) and thus no progesterone is made in the luteal phase, or second half, of the cycle. (aka progesterone deficiency).
- Ovulation is necessary for normal, regular menstrual cycles and fertilization (i.e. getting pregnant). Irregular menstrual cycles/periods are a sign of anovulation but it can also be confirmed with lab testing.
Hypothyroidism can cause menstrual irregularities:
- Irregular cycles: short (periods <21 days apart, aka polymenorrhea), long (periods >35 days apart, aka oligomenorrhea), absent menstrual cycles (no periods, aka amenorrhea)
- Irregular periods: heavy bleeding (periods >7 days, soaking through menstrual products every 1-2 hours, passing clots the size of a quarter or larger), breakthrough bleeding (spotting between periods)

Hypothyroidism & Preconception/Pregnancy

The purpose of the menstrual cycle is to prepare the body for pregnancy each month by perfecting the uterine lining for fertilization. Hypothyroidism can hinder a woman’s ability to get pregnant, stay pregnant, and have a healthy pregnancy/baby.

Hypothyroidism can cause subfertility, infertility, & pregnancy complications
- The effects mentioned above on hormones, ovulation, and menstruation, can make it very difficult, or even impossible, to become pregnant and may increase the risk of miscarriage. But these aren’t the only factors affecting fertility and pregnancy.
- Studies have shown that thyroid antibodies, especially TPO-Ab (elevated in Hashimoto’s disease), can lead to pregnancy complications, even when thyroid function is normal (which is why it’s so important to test an full thyroid panel that includes thyroid antibodies, even if TSH, with or without a fT4, have been within range).
- The presence of maternal thyroid autoantibodies is strongly associated with first trimester miscarriage and preterm delivery. Thus, thyroid autoimmunity is an important risk factor for miscarriage and preterm birth.
- Additionally, the presence of maternal thyroid autoantibodies have been associated with various health problems affecting mom and baby including increased risk of pregnancy induced hypertension, gestational diabetes mellitus, neurodevelopmental issues, low birth weight, and admission to NICU.
- Hypothyroidism before or during pregnancy can increase the risk of persistent hypothyroidism after delivery and of developing postpartum thyroiditis (PPT, especially with a history of having antithyroid antibodies)

Postpartum thyroiditis is an autoimmune disease that causes inflammation of the thyroid after giving birth and can involve both hyper- and hypo-thyroid activity of the thyroid

Hypothyroidism & Menopause

The effects of hypothyroidism extend beyond reproduction in the premenopausal years, causing problems in the menopausal years including changes in the timing and symptoms of menopause. There is a strong link between menopause and the thyroid.

Hypothyroidism is associated with earlier menopause
- Hypothyroidism is associated with early menopause (<age 45), premature menopause (<age 40), and the last menstrual period occurring before the natural age of menopause (age 45-55).
- Menopause is the cessation of monthly menstrual cycles/periods, characterized by low sex hormones, marking the end of fertility, which happens naturally following the loss of ovarian function.
- Optimizing thyroid levels in the premenopausal years optimizes ovarian health and function for as long as possible, which isn’t only important for menstrual cycles and fertility, but may help delay an earlier onset of menopause.
Hypothyroidism may worsen menopausal symptoms or be masked by menopausal symptoms
- Hypothyroidism and menopause (including perimenopause, menopause, and postmenopause - click here to learn more about these terms) have overlapping symptoms, including:
  - Irregular cycles/periods, hot flashes, night sweats, cold sensitivity, fatigue, forgetfulness, weight gain, sleep disturbance, mood changes, hair loss, joint pain, low libido, headaches, bone loss, palpitations
- Hot flashes, night sweats, and cold sensitivity are especially misconstrued symptoms, as they are defining symptoms of both menopause and hypothyroidism, due to the role of estrogen and thyroid hormones in temperature regulation.
- Not to mention, many of these overlapping symptoms are also common, vague, and can (and likely do) have several other causes anywhere from poor nutrition/lifestyle to underlying health conditions.
- This can complicate a woman’s experience as they transition into menopause, go through menopause, and become postmenopausal in the following ways:
  - 1) Hypothyroid symptoms can be mistaken for menopausal symptoms (or vice versa) and thus mask an underlying thyroid disorder
  - 2) An underlying thyroid disorder can make menopausal symptoms worse and should be considered especially when symptoms are severe
Hypothyroidism is more common in menopause
- Older age and being female are both risk factors for thyroid disease.
  - The risk of developing hypothyroidism (and other thyroid diseases including nodular goiters and thyroid cancer) increases with age and is about 10x more prevalent in women than men.
  - It is common for middle-aged women going through menopause to have an underactive thyroid and 12–20% of women over the age of 60 years may have an underactive thyroid.
- Physiological changes in the body associated with menopause can increase the risk of developing hypothyroidism
  - Leaky gut is a risk factor of hashimoto’s disease, which is common in menopause due to changes in the microbiome - click here to learn more about leaky gut & Hashimoto’s disease).
  - Menopause “starves” the thyroid of estrogen, which nourishes the gland and its receptors, so the thyroid makes less thyroid hormones and the thyroid receptors aren’t able to use those thyroid hormones properly
    - This whole situation is compounded by natural aging, an underlying thyroid disorder, as well as other effects of low estrogen such as increased body-wide inflammation

Hypothyroidism has profoundly negative effects on women’s health and hormones, increasing the risk of menstrual disorders, fertility problems, and menopausal symptoms - if you're struggling with any of these, get your thyroid tested! Hypothyroidism can be evaluated simply with a consultation and lab testing and it can be treated successfully with non-invasive interventions that target the underlying causes. ANAMARIA Natural Medicine is a functional and naturopathic clinic dedicated to helping women blossom into abundant health by addressing health and hormone imbalances at their roots using natural, evidence-based, and wholistic approaches. For personalized care, get started by scheduling a free discovery call.

Written by Dr. Jordan Valdez, ND, RD

Contact Information: (Telemedicine Only)

Social: @anamaria.naturalmedicine

Email: connect@anamarianaturalmedicine.com

Website: www.anamarianaturalmedicine.com

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