Showing all 74 terms.
Diagnosis and the condition
PMOS
Also called: Polyendocrine Metabolic Ovarian Syndrome
PMOS is the new name for PCOS, adopted in May 2026. It stands for Polyendocrine Metabolic Ovarian Syndrome. The old name pointed at ovarian cysts, which many people with the condition never have. The new one names what the condition actually is: a hormone and metabolic problem that involves the ovaries.
PCOS
Also called: Polycystic Ovary Syndrome
PCOS is the former name for PMOS. It is still the term most people search for, most doctors say, and most test results print. The two words mean the same condition. Nothing about your diagnosis changed when the name did.
PCOS 101: A Complete, Dietitian-Reviewed Guide to Polycystic Ovary Syndrome →
Rotterdam criteria
Also called: the 2 of 3 rule
The Rotterdam criteria are the rules doctors use to diagnose PMOS. You need two of these three: irregular or absent ovulation, high androgens on a blood test or by symptoms, and many small follicles on an ovarian scan. Other causes must be ruled out first. Two of three means you can be diagnosed without ever having a scan.
Rotterdam Criteria: Your Essential Guide to PCOS Diagnosis →
Polycystic ovary morphology
Also called: PCOM
PCOM is the scan finding: many small follicles sitting around the edge of the ovary. They are not cysts, and they are not dangerous. They are immature egg sacs that stalled before releasing. Having PCOM alone does not give you PMOS, and plenty of people with PMOS do not have it.
How Is PMOS Diagnosed? Rotterdam Criteria and the Full Workup →
Antral follicle count
Also called: AFC
The antral follicle count is the number of small follicles a sonographer counts on one ovary. Twenty or more per ovary counts toward a PMOS diagnosis under current guidance. The number varies with the scanner and the person counting, so it is one input, not a verdict.
What is an Ovarian Follicle? Understanding Its Role in PCOS →
Phenotypes A to D
Also called: PMOS subtypes
PMOS comes in four recognised patterns, labelled A through D, based on which of the Rotterdam features you have. Type A has all three and is usually the most metabolic. Type D has no high androgens. Your phenotype predicts your risks and your treatment better than the diagnosis alone does.
Insulin-Resistant PMOS Phenotype: Deep Dive on the Most Common PMOS Type →
Anovulation
Also called: not ovulating
Anovulation means a cycle where no egg is released. You can still bleed during an anovulatory cycle, so a period is not proof that you ovulated. Repeated anovulation is what makes cycles long, unpredictable, or absent.
Oligomenorrhoea
Also called: infrequent periods
Oligomenorrhoea means having fewer than about nine periods a year, or cycles longer than 35 days. It is the most common cycle pattern in PMOS. It usually reflects ovulation happening late or not at all.
Amenorrhoea
Also called: absent periods
Amenorrhoea means no periods for three months or more, when you are not pregnant. It sits at the far end of the same spectrum as oligomenorrhoea. It is worth investigating rather than waiting out, because the lining of the womb needs to shed regularly.
Your cycle
Follicular phase
Also called: the first half
The follicular phase runs from the first day of your period until you ovulate. Oestrogen rises through it. In PMOS this phase is often the long and unpredictable part, which is why cycles stretch rather than the second half.
PMOS Cycle-Syncing Exercise: Realistic Guide for Irregular Cycles →
Luteal phase
Also called: the second half
The luteal phase runs from ovulation to your next period, and it lasts about 12 to 14 days in most people. Progesterone rises through it. Because its length is fairly fixed, a long cycle almost always means a long follicular phase, not a long luteal one.
PMOS Cycle-Syncing Exercise: Realistic Guide for Irregular Cycles →
Cycle syncing
Also called: eating for your cycle
Cycle syncing means changing food or training to match the phase of your cycle. It assumes you know where in your cycle you are. With irregular ovulation that assumption often fails, so track first and sync second.
PMOS Cycle-Syncing Exercise: Realistic Guide for Irregular Cycles →
Hormones and blood tests
Androgens
Also called: male-type hormones
Androgens are a group of hormones that includes testosterone, DHEA-S and androstenedione. Everyone makes them. In PMOS the ovaries and adrenal glands make more than usual, which drives acne, unwanted hair growth and scalp hair thinning.
Hyperandrogenism
Also called: high androgens
Hyperandrogenism means androgen levels above the normal range, on a blood test or judged by symptoms. It is one of the three Rotterdam features. High insulin is the usual driver, because insulin tells the ovary to make more testosterone.
Free testosterone
Also called: unbound testosterone
Total testosterone counts all of it in your blood. Free testosterone counts only the part not stuck to a carrier protein, and that is the part that reaches your skin and hair follicles. Free testosterone can be high while total testosterone reads normal, so ask for both.
SHBG
Also called: sex hormone-binding globulin
SHBG is the protein that binds testosterone in your blood and keeps it inactive. High insulin lowers SHBG, which frees up more testosterone without your ovaries making any extra. Raising SHBG is one of the quietest ways to lower symptoms.
Sex Hormone-Binding Globulin (SHBG) and PCOS: Understanding the Connection →
DHEA-S
Also called: adrenal androgen
DHEA-S is an androgen made by the adrenal glands rather than the ovaries. When it is the only androgen that is high, the pattern is often called adrenal PMOS, and stress and cortisol matter more than insulin does.
Adrenal PCOS: Elevated DHEAS, Overlapping Symptoms with Inflammatory PCOS →
Androstenedione
Also called: A4
Androstenedione is an androgen that the body converts into testosterone. It is measured less often than testosterone, but it can be raised when testosterone reads normal. It comes from both the ovaries and the adrenal glands.
LH to FSH ratio
Also called: LH:FSH
LH and FSH are the two brain hormones that tell the ovary what to do. In PMOS, LH is often high relative to FSH, which is why a ratio above about 2 to 1 is sometimes quoted. It supports the picture but it is not a diagnostic test, and it is not part of the Rotterdam criteria.
Understanding Follicle Stimulating Hormone (FSH) and Its Role in PCOS →
AMH
Also called: anti-Mullerian hormone
AMH is made by small follicles, so having many of them pushes it high. AMH is often raised in PMOS and is being studied as a substitute for the ovarian scan. A high AMH here reflects follicle count, not fertility.
Anti-Müllerian Hormone (AMH) and PCOS: A Key Player in Diagnosis and Management →
Prolactin
Prolactin is the hormone behind milk production, and high levels stop ovulation. It is measured during a PMOS workup to rule out a different cause of missed periods. High prolactin is treated differently from PMOS, so it matters that the test is done.
Oestrogen
Also called: estrogen
Oestrogen is the main hormone of the first half of the cycle and it builds the womb lining. In PMOS it is often steady rather than cyclical, because ovulation is what normally ends its rise.
Progesterone
Progesterone is only made in quantity after you ovulate. No ovulation means no progesterone, which is why it is commonly low in PMOS. That missing progesterone is a large part of why cycles get unpredictable and the womb lining is not shed on time.
Cortisol
Also called: the stress hormone
Cortisol is released by the adrenal glands under stress, and it raises blood glucose to give you fuel. Chronic stress keeps it elevated, which worsens insulin resistance and pushes adrenal androgens up.
TSH
Also called: thyroid stimulating hormone
TSH is the standard first test of thyroid function. An underactive thyroid causes tiredness, weight gain and irregular periods, all of which look like PMOS. It is checked to rule that out, and thyroid problems are more common in people with PMOS.
PMOS and Thyroid: Hashimotos Overlap, Full Workup, and Treatment →
Insulin and metabolic terms
Insulin resistance
Also called: IR
Insulin resistance means your cells respond weakly to insulin, so your pancreas has to make more of it to move glucose out of your blood. It affects most people with PMOS, including many at a normal weight. High insulin then tells the ovaries to make more testosterone, which is how a blood sugar problem becomes a hormone problem.
PCOS Meal Plan for Insulin Resistance: Lower Your Insulin Naturally →
Hyperinsulinaemia
Also called: high insulin
Hyperinsulinaemia means too much insulin circulating in your blood. It is what insulin resistance produces, and it is the part that does the damage. Glucose can look completely normal for years while insulin runs high.
Fasting insulin
Fasting insulin measures insulin after an overnight fast. It is not on a standard blood panel, so you usually have to ask. It often turns abnormal years before fasting glucose does, which makes it the more useful early test.
HOMA-IR
Also called: insulin resistance score
HOMA-IR is a number calculated from your fasting glucose and fasting insulin together. It estimates insulin resistance without a specialist test. Above about 2.5 is commonly treated as insulin resistant, though the cutoff varies by lab.
HbA1c
Also called: glycated haemoglobin
HbA1c reflects your average blood glucose over roughly three months. It is the standard test for diabetes and prediabetes. Because it is an average, it can look fine while you are still spiking hard after meals.
OGTT
Also called: oral glucose tolerance test
In an OGTT you drink a measured sugar solution and have your blood taken over the next two hours. It catches problems that a single fasting test misses. Guidelines recommend it for PMOS rather than relying on fasting glucose alone.
Prediabetes
Also called: impaired glucose tolerance
Prediabetes means blood glucose above normal but below the diabetes threshold. It is a warning stage, not a disease, and it is often reversible. PMOS raises the risk substantially, which is why screening matters even when you feel well.
Dawn phenomenon
Also called: morning glucose rise
The dawn phenomenon is the natural rise in blood glucose in the early hours, from about 4am. Cortisol and growth hormone tell the liver to release stored glucose to wake you up. With insulin resistance your body clears it slowly, so you wake with glucose already high. This is why breakfast is the hardest meal of the day to get right.
Postprandial glucose
Also called: after-meal glucose
Postprandial glucose is your blood glucose after eating, usually measured one or two hours later. The size of that rise, not your fasting number, is what most food choices actually change.
PCOS Breakfasts That Don't Spike Blood Sugar (With Curves) →
Chronic low-grade inflammation
This is inflammation that stays switched on quietly for years, without an infection or injury behind it. It is common in PMOS and it worsens insulin resistance, which in turn worsens inflammation.
CRP
Also called: C-reactive protein
CRP is a blood marker of inflammation. The high-sensitivity version, hs-CRP, is the one used to detect the low-grade inflammation seen in PMOS. It rises with any infection, so one high reading on its own means little.
Visceral fat
Also called: belly fat around the organs
Visceral fat sits deep in the abdomen around your organs, unlike the fat you can pinch. It is hormonally active and it drives insulin resistance directly. It also responds well to change, which is the useful half.
Metabolic syndrome
Metabolic syndrome is a cluster of five things: a large waist, high triglycerides, low HDL cholesterol, high blood pressure and high blood glucose. Having three of the five counts. It is far more common in PMOS than in the general population.
NAFLD
Also called: fatty liver disease, MASLD
NAFLD means fat stored in the liver in people who drink little or no alcohol. It is now often called MASLD. It is strongly linked to insulin resistance, it is common in PMOS, and in its early stages it is reversible.
Symptoms and signs
Acanthosis nigricans
Also called: dark velvety patches
Acanthosis nigricans is dark, velvety thickening of the skin, usually on the neck, armpits or groin. It is not dirt and it does not scrub off. It is one of the most visible outward signs of high insulin.
Hirsutism
Also called: excess hair growth
Hirsutism means coarse, dark hair growing in a male pattern, such as the chin, upper lip, chest or stomach. It is caused by androgens acting on the hair follicle. Doctors often score it using the Ferriman-Gallwey scale.
Androgenic alopecia
Also called: female pattern hair loss
Androgenic alopecia is hair thinning driven by androgens, usually across the crown and along the parting, with the hairline kept. It is the opposite problem to hirsutism and the same hormone causes both.
Hormonal acne
Hormonal acne is acne driven by androgens rather than by hygiene. It clusters on the jaw, chin and neck, and it tends to be deep and sore rather than surface whiteheads. It responds to lowering androgens, slowly.
Skin tags
Also called: acrochordons
Skin tags are small soft growths, often on the neck, armpits or eyelids. They are harmless. Getting several of them at once is a recognised sign of high insulin, so they are worth mentioning to your doctor.
Medications
Metformin
Metformin is a prescription drug that lowers how much glucose your liver releases and makes your cells respond better to insulin. It is the most commonly prescribed medication for PMOS. It can deplete vitamin B12 over time, so that level is worth checking.
Spironolactone
Spironolactone is a prescription drug that blocks androgens at the hair follicle and the skin. It is used for hirsutism, acne and hair loss. It takes about six months to show its full effect, and it must not be taken while pregnant.
Spironolactone and PCOS: Understanding Its Role in Treatment →
Combined oral contraceptive
Also called: the combined pill, COC
The combined pill contains oestrogen and a progestin. In PMOS it is used to give regular bleeds, protect the womb lining and lower androgens by raising SHBG. It manages symptoms while you take it, and does not treat the underlying insulin problem.
PMOS and Birth Control: The Best Pills, the Worst, and Coming Off →
Letrozole
Letrozole is a tablet used to trigger ovulation when it is not happening on its own. It is now the recommended first choice ahead of clomiphene for PMOS. It is prescribed and monitored by a doctor.
GLP-1 receptor agonist
Also called: semaglutide, Ozempic, Wegovy, Mounjaro
GLP-1 receptor agonists copy a gut hormone that slows digestion and reduces appetite. They lower blood glucose and are used for type 2 diabetes and weight loss. Muscle loss is a real risk on them, so protein intake matters more than usual.
What to Eat on a GLP-1 With PCOS (Ozempic, Wegovy, Mounjaro) →
Supplements
Inositol
Also called: myo-inositol, D-chiro-inositol
Inositol is a compound that behaves like a B vitamin and improves how cells respond to insulin. Myo-inositol and D-chiro-inositol are the two forms studied, usually together in a 40 to 1 ratio. It is the best supported supplement in PMOS.
Myo Inositol: Benefits and Tips for Managing PCOS Symptoms →
Berberine
Berberine is a plant compound that lowers blood glucose through a pathway similar to metformin. It is sold as a supplement rather than a drug, so quality varies. It interacts with several medications, so check before adding it.
Berberine vs Metformin for PCOS: Which One Should You Start With? →
NAC
Also called: N-acetylcysteine
NAC is an antioxidant that the body converts into glutathione. It has been studied in PMOS for insulin sensitivity and ovulation. The evidence is thinner than for inositol but it is generally well tolerated.
N-Acetylcysteine (NAC) for PCOS: Benefits, Uses, and Considerations →
Vitamin D
Vitamin D acts as a hormone, and low levels are very common in PMOS. Deficiency is linked to worse insulin resistance. It is one of the few supplements worth testing for before you take it.
Vitamin D and PCOS: How This Essential Nutrient Affects Your Hormones →
Omega-3
Also called: EPA, DHA, fish oil
Omega-3 fats are found in oily fish, and the two active forms are EPA and DHA. They lower triglycerides and reduce inflammation. Plant sources like flaxseed give ALA, which the body converts to EPA and DHA only poorly.
Magnesium
Magnesium is a mineral involved in how insulin signals inside the cell. Low levels are more common in insulin resistance. The form matters: glycinate is used for sleep and cramps, citrate is more laxative.
Zinc
Zinc is a mineral used in hormone production and skin repair. It has been studied for acne and hair loss in PMOS. Too much zinc blocks copper absorption, so more is not better.
Spearmint tea
Spearmint tea has been studied as a mild anti-androgen, drunk twice a day. Trials are small and the effect is modest. It is cheap and safe, so it is a reasonable thing to add rather than to rely on.
Food and nutrition terms
Glycaemic index
Also called: GI
The glycaemic index ranks a carbohydrate food by how fast it raises blood glucose, on a scale to 100. It measures speed, not amount, and it is tested on a fixed 50 grams of carbohydrate rather than a real portion. That is why GI alone can mislead you.
Glycaemic load
Also called: GL
Glycaemic load combines the glycaemic index with how much carbohydrate is actually in your serving. It is the more useful of the two numbers. Watermelon has a high GI and a low glycaemic load, because a slice holds very little carbohydrate.
Low GI eating
Low GI eating means choosing carbohydrates that raise blood glucose slowly, rather than cutting carbohydrate out. It is one of the better studied dietary patterns for insulin resistance, and it is easier to sustain than a low-carbohydrate diet.
Net carbs
Net carbs is total carbohydrate minus fibre, and sometimes minus sugar alcohols. It is a marketing term rather than a regulated one, and the maths is generous on many packaged products. Read the total carbohydrate figure as well.
Soluble fibre
Soluble fibre dissolves in water and forms a gel in your gut, which slows glucose absorption. Oats, beans, chia, flaxseed and apples are good sources. It is the type of fibre that does most of the blood glucose work.
Fibermaxxing for PCOS: How More Fibre Fixes Insulin, Gut Health, and Cravings →
Beta-glucan
Also called: oat fibre
Beta-glucan is the soluble fibre in oats and barley that thickens in the gut. Pooled trials show it lowers the glucose rise by about 23%. The effect depends on the fibre staying intact, which is why instant oats often do nothing.
Resistant starch
Resistant starch is starch that passes through the small intestine undigested and feeds your gut bacteria instead. Cooking and then cooling potatoes, rice or pasta increases it. Reheating does not undo the change.
Food order
Also called: meal sequencing
Food order means eating the parts of a meal in a set sequence: protein and vegetables first, carbohydrate last. In adults with prediabetes it cut the peak glucose rise by more than 40%, with no change to the food itself. It is the cheapest intervention on this page.
Advanced glycation end products
Also called: AGEs
AGEs form when sugars bond to proteins or fats, especially under high dry heat like grilling, roasting and frying. They are linked to inflammation and are found at higher levels in PMOS. Steaming, poaching and stewing produce far fewer.
Anti-inflammatory diet
An anti-inflammatory diet emphasises oily fish, olive oil, vegetables, pulses, nuts and whole grains, and limits ultra-processed food. It overlaps heavily with the Mediterranean pattern. It targets the inflammation half of PMOS rather than the insulin half.
Low-carbohydrate diet
Also called: low carb
A low-carbohydrate diet usually means under about 130 grams of carbohydrate a day. It reliably lowers insulin. The trade-off is that it is harder to stick to over years, and adherence is what decides whether any diet works.
Ketogenic diet
Also called: keto
A ketogenic diet keeps carbohydrate very low, usually under 50 grams a day, so the body burns fat for fuel and makes ketones. It lowers insulin sharply. It is restrictive, and long-term studies in PMOS are still limited.
PCOS Friendly Keto Diet: Complete Guide to Low-Carb Eating →
Mediterranean diet
The Mediterranean diet is a pattern built on olive oil, vegetables, pulses, fish, nuts and whole grains, with little red or processed meat. It has the strongest long-term evidence of any dietary pattern for heart and metabolic health.
Protein target
Also called: protein floor
A protein target is a minimum amount of protein per meal, commonly 25 to 30 grams. Hitting it at every meal, rather than loading it all into dinner, is what keeps you full and steadies blood glucose. Breakfast is where most people miss it.
Appetite and gut
Gut microbiome
Also called: gut flora
The gut microbiome is the community of bacteria living in your intestine. It is less diverse in PMOS than in people without it. Fibre feeds it, and what it produces affects inflammation, appetite and hormones.
Leptin resistance
Leptin is the hormone that tells your brain you have enough energy stored. In leptin resistance the signal stops landing, so hunger stays switched on even when stores are full. It travels alongside insulin resistance.
Ghrelin
Also called: the hunger hormone
Ghrelin rises before meals to make you hungry and falls after you eat. Poor sleep raises it. Protein and fibre suppress it more effectively than refined carbohydrate does.
Why PCOS is now called PMOS
In May 2026 the condition was renamed Polyendocrine Metabolic Ovarian Syndrome. The old name put the emphasis on ovarian cysts, which are not cysts at all and which many people with the condition never have. The new name describes what is actually happening: a hormone and metabolic condition that involves the ovaries. Your diagnosis did not change, and most test results and clinic letters still say PCOS. Both names are used throughout this glossary for that reason.
A term we have not defined?
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