Endometrial hyperplasia is a precancerous condition in which the lining of the uterus, or endometrium, becomes unusually thick due to a hormonal imbalance. Endometrial hyperplasia may lead to various symptoms, such as heavy menstrual periods, spotting, and post-menopausal bleeding.

While risk factors vary, some conditions that cause too much of the hormone estrogen can lead to endometrial hyperplasia. Depending on the severity of the condition, treatment may involve observation, managing certain risk factors, medication, and surgery.

This article discusses the symptoms, causes, and risk factors of endometrial hyperplasia. It also covers how it’s diagnosed and treated.

Endometrial Hyperplasia Symptoms

Endometrial hyperplasia can cause abnormal uterine bleeding. This can include:

There are two types of endometrial hyperplasia:

  • Heavier than normal menstrual bleedingBleeding in between your periods, or spottingPost-menopausal bleeding

When to Call Your Healthcare Provider

Reach out to your healthcare provider if you:

  • Have pelvic pain or cramping and aren’t on your period
  • Experience any abnormal uterine bleeding (with or without accompanying low back pain*)
  • Feel weak or faint because of excessive uterine bleeding
  • Have a fever, in addition to abnormal uterine bleeding
  • Experience worsening and more frequent symptoms
  • Bleed after sex

*Endometrial hyperplasia is not associated with back pain, but endometrial cancer is.

Causes

Endometrial hyperplasia is caused by a hormonal imbalance, specifically too much estrogen compared to progesterone. Estrogen is the hormone that is responsible for causing the normal thickening of the endometrium during the first half of your menstrual cycle.

When balanced with the right amount of progesterone, your endometrium builds up, but then thins out. When there is too much estrogen, the lining is overstimulated and continues to thicken. Over time, that thickened lining begins to develop abnormal changes.

Risk Factors for Endometrial Hyperplasia

Conditions that cause excess estrogen that can lead to endometrial hyperplasia include:

Is Endometrial Hyperplasia Hereditary?

Studies suggest that certain types of endometrial hyperplasia and endometrial cancer are genetically similar. Because endometrial cancer can run in families, this suggests that there may be a hereditary component to endometrial hyperplasia as well.

  • ObesityAnovulation, or lack of ovulation, that may be caused by perimenopause or polycystic ovarian syndromeTaking hormones, like estrogen replacement medication or tamoxifen, which is used to treat certain types of breast cancersHormone-producing tumors

Obesity

Fat tissue converts other hormones to estrogen. This results in extra estrogen that stimulates the lining of the uterus in addition to the normal estrogen produced by your ovaries. If your BMI is over 35, you have a significantly increased risk of developing endometrial hyperplasia.

Anovulation

Anovulation happens when you don’t ovulate, meaning an egg doesn’t release from your ovaries. If you don’t ovulate, your ovary won’t increase its production of progesterone. This increase in progesterone is necessary for the lining of your uterus to shed. In other words, you won’t get your period.

In some types of anovulatory cycles, this leads to too much estrogen compared to progesterone. This unbalanced estrogen results in abnormal thickening of the endometrium. Eventually, you will have some type of abnormal uterine bleeding.

This may cause irregular and heavy periods or bleeding between your periods. Common causes of this type of hormonal imbalance include:

  • Perimenopause, which is the stage leading up to menopause
  • Polycystic ovarian syndrome (PCOS), which causes the ovaries to produce excess male hormones or androgens

Taking Hormones

Hormones that are taken as medications or hormone therapy can increase your estrogen levels relative to your progesterone. One example is estrogen replacement. If you’re taking estrogen replacement and still have a uterus, you need to take some form of a progestin (progesterone). This helps prevent your endometrium from being overstimulated when taking estrogen.

Another hormonal medication that can cause abnormal thickening of the endometrium is tamoxifen. Tamoxifen is a drug that is called a selective estrogen receptor modulator or SERM. SERMs are drugs that affect the estrogen-sensitive parts of your body in different ways.

Tamoxifen is often used in the treatment of hormone-sensitive breast cancers. That’s because it opposes the effects of estrogen in the breast tissue. However, tamoxifen stimulates the estrogen receptors in the lining of the uterus. It acts like an estrogen and can cause endometrial hyperplasia.

Estrogen-Producing Ovarian Tumors

Hormone-producing tumors are not a common cause of endometrial hyperplasia. However, there are certain (usually benign) ovarian tumors that produce excess estrogen. 

See your healthcare provider if you are using hormone replacement therapy or tamoxifen and develop abnormal uterine bleeding.

Endometrial Hyperplasia Diagnosis

Your healthcare provider may order several tests to diagnose endometrial hyperplasia and rule out other conditions that may be causing abnormal uterine bleeding. These tests may include:

  • Endometrial biopsy: During this quick procedure, your healthcare provider removes a small amount of tissue from the endometrium. This may cause some cramping and discomfort. The tissue is then examined under a microscope for abnormal cells.
  • Hysteroscopy: This is a same-day surgical procedure that allows your healthcare provider to directly observe the lining of the uterus and ensures all areas of the endometrium are properly sampled.
  • Transvaginal pelvic ultrasound: This imaging procedure uses sound waves to produce images of the pelvic cavity and the organs within it. This may be used to rule out other causes of abnormal bleeding.
  • Blood tests: Certain blood tests may be used to rule out other causes of abnormal bleeding. Blood tests cannot diagnose endometrial hyperplasia.

Determining the Type of Endometrial Hyperplasia

When the pathologist looks at the sample of your endometrium under the microscope they look specifically at changes in the two components of your endometrium, the glands and the supportive tissue called stroma.

Endometrial hyperplasia is diagnosed when there are more glands relative to stroma than you would find in normal proliferative or cycling endometrium.

The pathologist will then comment on whether there are atypical appearing cells in this abnormally thickened endometrium. This leads to two classifications of endometrial hyperplasia:

  • Hyperplasia without atypia, which has normal-looking cellsAtypical hyperplasia, which has abnormal cells that are considered precancerous

Endometrial Hyperplasia Treatment

It is very important that all endometrial hyperplasia be closely followed or treated. The course of treatment will depend on whether or not there is atypia, or abnormal cells.

Endometrial hyperplasia is not endometrial cancer. However, in some cases of significant atypical hyperplasia, a very early stage endometrial cancer may already be present.

Endometrial Hyperplasia Without Atypia

When there are no atypical cells present, the chance of endometrial hyperplasia eventually becoming endometrial cancer is very unlikely. The evidence suggests that only about 5% of individuals with endometrial hyperplasia without atypia will develop endometrial cancer. It is also likely that this type of endometrial hyperplasia will resolve on its own over time.

Modifying Risk Factors

The first line of treatment is to look for risk factors that you can change. For example, if you are significantly overweight or obese, losing weight will help decrease the excess estrogen produced by fat cells. This will allow the lining of your uterus to reset itself.

If you’re taking hormone replacement therapy, your healthcare provider may need to adjust your dose or recommend that you discontinue using it.

Progesterone

Your healthcare provider may recommend using progestin treatments to counteract the thickening effect of the excess estrogen on your endometrium. Reasons your healthcare provider may suggest treating you with progestin include:

  • Observation and lifestyle changes didn’t work.You are having abnormal uterine bleeding.You want the fastest result.

An oral progesterone or a progesterone-containing IUD may be suggested for the treatment of endometrial hyperplasia without atypia. This can include the levonorgestrel IUD (Mirena).

If your BMI is over 35, the progesterone treatment may not work well unless you also lose weight. You should discuss with your healthcare provider which type of progesterone treatment is best for you.

Hysterectomy

Whether you chose observation or treatment with progesterone, you will have to be followed closely with interval endometrial sampling. This helps to assure that the endometrial hyperplasia is gone and doesn’t come back.

Experts say that a hysterectomy should not be offered as a first-line treatment option for endometrial hyperplasia without atypia. That’s because of the overall effectiveness of progesterone treatment and the low risk of developing endometrial cancer.

However, there are certain situations where a hysterectomy may be an appropriate treatment option for individuals who are done having children. Your healthcare provider may recommend a hysterectomy if:

  • During follow-up, you develop atypical hyperplasiaThe hyperplasia does not improve after 12 months of progesterone treatmentYou are having significant abnormal bleedingYou develop endometrial hyperplasia again after it was successfully treatedYou do not want to undergo the repeat endometrial biopsies required with progesterone treatment

Endometrial Hyperplasia With Atypia

If you have hyperplasia with atypia, there is a much more significant risk of developing endometrial cancer. Treatment is a bit more aggressive because of that increased risk. In fact, experts recommend hysterectomy as the first-line treatment for atypical hyperplasia in individuals who are done having children.

If you are diagnosed with atypical hyperplasia and planning on trying to get pregnant, you will likely be treated with progesterone. Preferably, this would be with the levonorgestrel IUD.

You will have more frequent endometrial sampling to assure that the atypical hyperplasia has been treated adequately. Your healthcare provider may suggest you see a fertility specialist to complete your childbearing as soon as you possibly can.

Your healthcare provider will likely suggest having a hysterectomy after you are done having children. That’s because atypical endometrial hyperplasia has a high likelihood of recurrence.

Outlook

The outlook for most individuals with endometrial hyperplasia tends to be good, with many cases resolving on their own or responding well to progestin treatment.

If you have hyperplasia with atypia, your healthcare provider may recommend more aggressive treatment options to reduce or eliminate your risk of developing endometrial cancer.

Summary

Endometrial hyperplasia is caused by a hormone imbalance that allows your endometrium to thicken and develop abnormal changes. This can lead to irregular bleeding that may be heavier than normal, in between periods, or after menopause.

If endometrial hyperplasia is suspected, your healthcare provider will likely recommend a biopsy of your uterine lining. Endometrial hyperplasia can be classified as one of two types. Hyperplasia without atypia has normal-looking cells, and atypical hyperplasia has abnormal cells considered precancerous.

In hyperplasia without atypia, treatment may include risk factor management, such as losing weight or discontinuing hormone therapy. You may also take progesterone treatments.

If you have atypical hyperplasia, a precancerous condition, your doctor may recommend a hysterectomy. If you’re still planning on getting pregnant, your doctor may suggest progesterone treatments along with frequent monitoring of your condition.