Hysterectomy—technically, the removal of a woman’s uterus—is one of the most common surgeries in women. In some cases, the ovaries, fallopian tubes, and cervix are also removed. Removing the ovaries (oophorectomy) is estimated to occur in close to half of all hysterectomies. It’s estimated that by the age of 60, one in three women in the United States has had some type of hysterectomy.
Hysterectomy is performed to treat cancer of the uterus, cervix, or ovaries. But 90 percent of hysterectomies, however, are for benign conditions, including:
- Uterine fibroids that are causing bleeding, pain, or other symptoms
- Uterine prolapse, when the uterus drops into the vaginal canal
- Endometriosis, when tissue builds up around the uterus and other organs
- Thickening of the uterus
- Abnormal and chronic vaginal bleeding
- Chronic pain in the pelvic area
Having a hysterectomy affects your thyroid health in several ways:
- Hormonal changes after hysterectomy can negatively impact your thyroid function.
- If you take hormone replacement therapy (HRT) after hysterectomy, it can negatively affect your treatment for hypothyroidism.
- If you are postmenopausal, hysterectomy increases your risk of thyroid cancer.
Let’s explore these potential effects.
If you have not gone through menopause and have both of your ovaries removed during a hysterectomy, you enter “surgical menopause.” The drop in hormones, specifically estrogen and progesterone, triggers an immediate menopause. If one or both ovaries remain, you won’t menstruate, but you may still produce enough hormones to have what’s known as a “natural menopause” later.
Like natural menopause, surgical menopause can affect your thyroid. To understand how, you need to know how estrogen and progesterone — the hormones that drop dramatically after surgical menopause — interact with your thyroid.
After natural or surgical menopause, estrogen, and progesterone drop, but not necessarily evenly. You can end up in a situation where you have too much estrogen in comparison to your progesterone level — a condition known as estrogen dominance.
Estrogen dominance increases your levels of thyroid binding globulin, known as TBG. TBG attaches to your thyroid hormones and makes less thyroid hormone available to reach your cells and help them take in oxygen and energy. You can become more hypothyroid at the cellular level. An important note: Estrogen dominance does not increase thyroid stimulating hormone (TSH) levels, so they do not reflect the extent of your hypothyroidism.
What should you do? If you are hypothyroid and have a hysterectomy — especially one that removes one or both ovaries — make sure your doctor understands that while your TSH appears to be normal, your free thyroxine (Free T4) and free triiodothyronine (Free T3) may be affected. Make sure you periodically test Free T4 and Free T3. Based on the results, your dosage of thyroid hormone replacement may need to be adjusted to ensure optimal thyroid function.
Hormone Replacement Therapy and Your Thyroid
After surgical menopause, some women are prescribed HRT to relieve the onset of menopausal symptoms such as hot flashes. HRT medications include estrogen, progesterone, or both hormones.
Some common oral HRT medications include Premarin, Estrace, and Estratab. There are also combination oral estrogen/progesterone drugs, including Activella, Angeliq, and Prempro. (The U.S. Food and Drug Administration has a comprehensive list of hormonal medications that include estrogen.) In some cases, doctors may prescribe custom compounded bioidentical hormone capsules. HRT is also available as patches, gels, and creams.
When taken in an oral form, however, estrogen raises your TBG levels, reducing the amount of available thyroid hormone.
What should you do? If you are hypothyroid and have a hysterectomy with oophorectomy, taking any oral HRT medication that includes estrogen means that you will likely need an increased dose of thyroid hormone replacement medication to counteract the effects of the estrogen. You should have Free T4 and Free T3 levels evaluated, and your medication dosage adjusted to ensure that you are getting optimal thyroid hormone replacement.
An important note: Transdermal estrogen — estrogen patches, gels, and creams — does not elevate TBG levels, and as a result, does not appear to affect your thyroid. If you need HRT after hysterectomy, a transdermal delivery option may be a better choice for you if you are taking thyroid hormone replacement medication for hypothyroidism.
Thyroid Cancer Risk
Whether or not you have a preexisting thyroid condition, having a hysterectomy increases your risk of developing thyroid cancer. Thyroid cancer is now the fifth-most-common cancer in women.
Researchers have conducted a number of studies on hysterectomy and thyroid cancer. A critical study published in 2016 in the Journal of Clinical Endocrinology & Metabolism (JCEM) found that hysterectomy — whether or not the ovaries are removed — significantly increases the risk of developing thyroid cancer in postmenopausal women. A Finnish study found that the risk is highest in the first two years after the hysterectomy.
One interesting finding in the JCEM study: Using estrogen drugs actually reduces the risk of developing thyroid cancer in women who have had a hysterectomy, but who still had their ovaries. The risk reduction was the greatest in women who had estrogen therapy for 10 or more years.
What should you do? Given these findings, experts now recommend that when you are deciding to have a hysterectomy for a benign condition, your potential risk of thyroid cancer should be considered.
Researchers have not determined whether a hysterectomy itself is creating the increased risk of thyroid cancer, or if the gynecological conditions that lead to the hysterectomy are related to thyroid disease and thyroid cancer. If you do have a hysterectomy, however, it’s important to be alert to any potential signs or symptoms of thyroid cancer.