What to know about polyendocrine metabolic ovarian syndrome
- Renaming the condition better reflects its affects on hormonal, metabolic and reproductive health, not just the ovaries
- PMOS can affect the entire body and increase the risk of serious long-term health conditions, including diabetes, cardiovascular disease and endometrial cancer
- There is no cure for PMOS, but symptoms can be effectively managed through personalized care, including lifestyle changes and medication
For more than
170 million women worldwide living with what was once called polycystic ovary syndrome — commonly known as PCOS — four new letters mark a renewed sense of hope.
Earlier this year, the condition was renamed polyendocrine metabolic ovarian syndrome, or PMOS. The new name aims to better capture its complexity and help reshape how it’s understood, diagnosed and treated.
The former name arose from the characteristic appearance of ovaries containing many small follicles, which were historically described as cysts. Eventually, it was determined that these structures are actually immature ovarian follicles, not true ovarian cysts.
"Because ovulation is affected by PMOS, multiple follicles start to develop, giving the ovaries a polycystic appearance," explains Dr. Shirine Usmani, clinical investigator and endocrinologist at UHN.
“Polyendocrine metabolic” describes the interplay of hormonal and metabolic conditions that affect health across the lifespan.
What is PMOS?
PMOS is a lifelong hormonal, metabolic and reproductive health condition, which has effects on multiple systems in the body.
Often diagnosed in women of reproductive age, PMOS can cause a wide range of symptoms that vary from person to person and can change or extend throughout a person’s lifetime.
Symptoms may include:
- missed or irregular periods, or heavy or long periods
- irregular ovulation
- challenges getting pregnant or infertility
- acne or oily skin
- male-pattern hair growth (hirsutism), or hair thinning or loss
- weight gain or difficulty losing weight
- polycystic-appearing ovaries
Experiencing PMOS symptoms can also take a toll on a person’s mental health and quality of life, putting those with the condition at higher risk for developing anxiety, depression and body image or eating disorders.
Why was PCOS renamed to PMOS?
Following a 14-year long consensus process between clinicians, patients, researchers and international societies, the new name was announced in May 2026 at the European Congress of Endocrinology in Prague and published in the peer-reviewed medical journal, The Lancet.
A driving factor that led to implementing the change was to better capture the complexity of the condition.
“One of the biggest myths about PMOS is that you need to have ovarian cysts. You do not,” says Dr. Tehmina Ahmad, staff endocrinologist at UHN.
“Calling it PMOS better reflects what we've clinically known for years, which is that this is a complex endocrine and metabolic condition that involves multiple hormone systems. It is not simply a condition of ovarian cysts.”
What can patients with PMOS expect following the name change?
Although the name change doesn’t immediately affect the diagnostic criteria or treatment of the condition, its impact extends to how health care providers and patients think and speak about the condition.
“When we call PMOS what it is, an endocrine and metabolic condition, we start asking different questions," says Dr. Ahmad.
"Better questions lead to more comprehensive care. It’s that care that we’re looking to improve.”
Understanding the condition in its totality also helps to shed light on the increased risk for other health conditions that PMOS brings.
Complications may include:
- diabetes
- high blood pressure
- high cholesterol
- cardiovascular disease
- obesity
- sleep apnea
- endometrial cancer.
How is PMOS diagnosed?
According to Dr. Usmani, PMOS is a diagnosis of exclusion.
“It's really important that if someone has symptoms consistent with PMOS, they're not just immediately given the diagnosis. Instead, as clinicians, we look at other things to make sure they don't have other conditions that could be causing these symptoms,” she says.
After ruling out other causes, women must meet two of three criteria to receive a PMOS diagnosis:
- Irregular periods
- Blood work or evidence (e.g. acne, hirsutism) that indicate high androgen levels — hormones that are typically found in higher amounts in males than females
- Ultrasound image that displays polycystic-appearing ovaries or a blood test that indicates an increased growth of ovarian follicles
How is PMOS treated?
While there is currently no cure for PMOS, its symptoms can be reduced or managed through lifestyle changes, such as a healthy diet and regular exercise, as well as medications and other treatments.
As a condition that affects multiple systems throughout the body, treating PMOS often involves a team of specialists who tailor care based on a patient’s symptoms, health risks and goals.
“At UHN, we have access to a number of subspecialties that can help with specific areas of care for patients with PMOS,” says Dr. Usmani.
“We may collaborate or refer patients to obstetrics and gynecology, dietitians, dermatologists or fertility clinics if that is what they are seeking. Because PMOS is also associated with an increased risk of endometrial cancer, oncology may play a role in a patient’s care as well.”
UHN care teams take an integrated approach with primary care providers to ensure patients receive the ongoing support they need.
“We manage and even co-manage with family doctors because these patients are going to need long-term follow-up,” says Dr. Usmani.
