Polyendocrine metabolic ovarian syndrome (PMOS)

What is polyendocrine metabolic ovarian syndrome (PMOS) ?

PMOS is a common condition that affects 1 in 8 women in the UK. It's characterised by hormonal imbalances, which can affect your weight, skin, metabolic and mental health and reproductive system.

How is PMOS diagnosed?

PMOS is diagnosed following investigations and exclusion of other specific conditions. You could be diagnosed with PMOS if you have any two of the following:

1. Irregular or no periods: Irregular means less than 9 periods a year.
2. High levels of androgens (such as testosterone): This can be shown in a blood test or symptoms that suggest higher androgen levels such as excess hair growth on the face or body, loss of hair from the scalp, as well as acne
3. Polycystic ovaries: There are multiple cysts on the ovaries (more than 12 cysts on one ovary).

Your consultant may order an ultrasound scan to confirm you have polycystic ovaries. They may also order blood tests to check your hormone levels.

Why did the name change from PCOS to PMOS?

Before 12 May 2026, the syndrome was referred to as PCOS (Polycystic Ovary Syndrome), but it was decided that this name placed too much emphasis on the ovaries, when this is a multisystem condition that can affect several areas of the body.

Polycystic ovaries are slightly enlarged with fluid-filled bubbles just below the surface, and contain eggs that have not fully developed. Most women with polycystic ovaries will not have any problems other than irregular periods. Having polycystic ovaries does not necessarily mean you have PMOS.

The name change was therefore to help improve diagnosis and care of the condition, by including the ovaries as well as the endocrine and metabolic systems within the title.

What causes PMOS?

The exact cause of PMOS remains unclear. It’s likely that there is a genetic link, as it tends to run in families (but not always).

However those with PMOS may have an increased risk of other health concerns, such as diabetes, stroke, fertility difficulty, sleep apnoea and cancer of the womb.

What are the symptoms of PMOS?

Symptoms of PMOS often start in the years after puberty into the early 20s, and can vary greatly between women. 

Many women with PMOS may have very mild symptoms, so much so that they don’t realise they have the condition until they have difficulty getting pregnant.

However, there are still many women who do have symptoms. Those women will have some or all of the symptoms listed below, to different degrees of intensity, depending on the individual. These symptoms include:

• Irregular or no menstrual periods
• Difficulty getting pregnant
• Excessive hair growth (hirsutism) usually on the face, arms, chest, back or buttocks
• Thinning hair and hair loss from the head
• Oily skin or recurring acne
• Dark skin patches
• Skin tags
• Weight gain.

If you are concerned about any of these symptoms you should visit your GP for an initial diagnosis. You may be referred to a consultant gynaecologist who can confirm and treat PMOS.

The role of hormones in PMOS

Women with PMOS tend to have higher than normal levels of insulin and are more likely to be resistant to insulin.

Insulin resistance is a very common feature of PMOS and affects around 75% of all women with the condition regardless of their weight, but it is an issue that can be made worse by an increase in weight.

What is insulin resistance?

Insulin is a hormone that helps to control the level of sugar in the blood. Insulin resistance means the cells that use glucose as an energy source (muscle, fat and liver cells) do not respond to normal levels of insulin, so the body compensates by producing more insulin, which helps the glucose enter the cells.

The impact of high levels of insulin

High Insulin levels can lead to other hormonal problems including high levels of luteinizing hormone (LH), which can impact ovulation, leading to irregular or no periods.

High levels of LH can also cause an increase in testosterone. Typically considered a male hormone, all women produce a small amount of testosterone in their ovaries, but the majority of it is usually converted to oestrogen. For women with PMOS, the amount of testosterone produced tends to be higher, which can also affect ovulation and make the symptoms of PMOS worse.

Insulin resistance is a leading cause of developing pre-diabetes, diabetes in pregnancy or type-2 diabetes later in life. 

How is PMOS treated?

There is no cure for PMOS, but you can manage the symptoms of PMOS. You and your consultant will work on a treatment plan based on your symptoms, your plans for having children, and your risk of long-term health problems such as diabetes and heart disease.

Treatments could include:

• Weight loss and lifestyle changes (diet and exercise)
• Medications to balance hormone levels
• Medications to control excess hair and acne
• Fertility medications to stimulate ovulation
• Laparoscopic surgery.

Alternative treatment options

Additional treatments include therapies such as acupuncture. Many patients who have irregular cycles with their PMOS have worked with acupuncture practitioners to regulate their cycles. It may not be a treatment for everyone, but is another option that can be explored for treatment.

How to manage PMOS

There are ways to improve symptoms, increase the chances of getting pregnant, and decrease your risk of other health concerns developing.

One of the most recommended routes to mitigate the effects of PMOS is living a healthy lifestyle. Maintaining a healthy weight, eating a balanced diet, not smoking, decreasing your alcohol intake and doing regular exercise will reduce your overall risk of the long-term health concerns associated with PMOS.

Losing as little as 1 to 2kg of excess body fat can help regulate your cycle, decrease insulin resistance thereby decreasing your insulin and androgen levels, and can improve your chances or getting pregnant.

There are some medications that can help manage the symptoms that occur with PMOS and will depend on whether you are trying to get pregnant or not.

If you aren't trying to get pregnant

• The combined oral contraceptive pill or the progesterone only pill: These can suppress your ovaries enough to stop the production of androgens. The benefit of the combined pill is that it will provide you with a regular and predictable bleeding pattern, while the progesterone-only pill may stop you bleeding altogether. Decreasing the amount of androgen produced can improve acne and excess hair growth (especially the combined contraceptive pill).
• A specific pill called Dianette: This contains an anti-androgen is very useful to improve acne and excess hair growth, as well as regulate your bleeding pattern. However, this should only be used for a few months before you change over to another contraceptive pill.
• Hormonal tablet: If you do not want to, or cannot use hormonal contraception, then your GP may prescribe you a hormonal tablet to take for a few days if your menstrual cycle is very infrequent. This should be taken every 3 months and will make you bleed, keeping your womb lining thin and decreasing the risk of womb cancer occurring.
• Metformin: This is useful to decrease insulin resistance and reduce androgen levels slightly, but it is not licenced for this use. However, many doctors in the UK do prescribe it out of licence in women who have already implemented the lifestyle changes recommended and still have insulin resistance.
• Weight loss medications: These can also improve insulin resistance by decreasing your body fat percentage.

If you are trying to get pregnant

• Metformin: This may help you to start ovulating again
• Fertility medications: These can also be used to stimulate ovulation, allowing you to get pregnant.