PCOS: symptoms, hormones and how testing can help you manage it

Androgen excess: the hormone most commonly out of balance

The defining feature of PCOS in most affected women is excess androgen production, primarily testosterone, from the ovaries. Even a modest elevation in circulating androgens can produce the symptoms most associated with the condition: acne that tends to be cystic or persistent beyond the teenage years, unwanted hair growth on the face, chin, chest, or abdomen (hirsutism), and thinning hair on the scalp. The degree of androgen elevation varies widely between women, which explains why some experience severe symptoms and others only subtle signs. Testing total testosterone alongside SHBG (sex hormone-binding globulin) gives the clearest picture, because SHBG binds to testosterone and makes it biologically inactive. Low SHBG, which is common in PCOS, increases the amount of free active testosterone even when the total number looks normal.

Insulin resistance: the underlying driver in most women with PCOS

The majority of women with PCOS have some degree of insulin resistance, and researchers increasingly view this as one of the central mechanisms sustaining the hormonal imbalance rather than a separate complication. When cells become resistant to insulin's signal, the pancreas compensates by producing more. Elevated insulin then stimulates the ovaries to produce additional testosterone, which in turn suppresses SHBG and drives the androgen excess that produces the visible symptoms. Critically, this pattern of insulin resistance can be present even in women with a healthy body weight: PCOS-related insulin resistance is not simply a consequence of excess weight but appears to be an intrinsic feature of the condition in many cases. Testing fasting glucose and HbA1c gives a measure of blood sugar management over time, while fasting insulin provides the most direct signal of insulin resistance that is developing before glucose levels become elevated.

Disrupted ovulation and irregular periods

PCOS disrupts the normal follicle development cycle in the ovaries, causing follicles to partially develop but not release an egg. This results in irregular, infrequent, or absent periods, which creates unpredictability around fertility. The LH-to-FSH ratio is often elevated in PCOS, with LH disproportionately high relative to FSH, because the signalling from the brain to the ovaries is disrupted. In women seeking a PCOS blood test UK, LH and FSH measured in the early part of the menstrual cycle (or at any time in women who are not having regular periods) can support the clinical picture, though the LH:FSH ratio is no longer the primary diagnostic criterion it once was.

Lipid abnormalities and cardiovascular risk

Women with PCOS are statistically more likely to have an unfavourable lipid profile: elevated triglycerides, low HDL, and sometimes elevated LDL. This pattern reflects the metabolic consequences of insulin resistance and is one of the reasons that PCOS carries a longer-term association with cardiovascular risk. Testing a full lipid panel alongside the hormonal markers gives a more complete picture of the metabolic burden of the condition. Triglyceride levels in particular tend to be sensitive to changes in diet and exercise, making them a useful marker to track as you make lifestyle adjustments.

Thyroid dysfunction as a co-occurring condition and differential diagnosis

Thyroid conditions, particularly Hashimoto's thyroiditis, are more common in women with PCOS than in the general population. Hypothyroidism produces irregular periods, weight gain, fatigue, and hair changes that overlap significantly with PCOS symptoms. Measuring TSH, and ideally Free T3 and Anti-TPO antibodies, helps to establish whether thyroid dysfunction is contributing to the symptom picture or whether PCOS is the primary driver. Some women have both conditions simultaneously.

Low-grade inflammation as a contributing mechanism

An emerging body of evidence links PCOS to increased low-grade systemic inflammation, measurable via CRP. Women with PCOS tend to have elevated CRP compared to women without the condition, even when weight is accounted for. Chronic low-grade inflammation can worsen insulin resistance and further disrupt ovarian function, creating another self-reinforcing loop within the PCOS mechanism.

PCOS is a clinical diagnosis requiring two of three features (irregular periods, evidence of excess androgens, and polycystic ovaries on ultrasound), but blood testing is an essential part of establishing the hormonal picture and ruling out other causes. A GP will typically request some or all of the following, and the results are interpreted alongside your symptoms and history rather than as standalone diagnostic tools.

Total testosterone is the primary androgen marker. Elevated total testosterone supports the diagnosis of PCOS, though a normal result does not rule it out: SHBG must also be considered.

SHBG (sex hormone-binding globulin) is consistently low in PCOS, which increases the amount of biologically active free testosterone regardless of total testosterone levels.

LH (luteinising hormone) and FSH (follicle-stimulating hormone) assess the pituitary-ovarian signalling axis. An elevated LH-to-FSH ratio is common in PCOS, though not universal.

HbA1c reflects three-month blood sugar control and screens for pre-diabetes risk, which is significantly elevated in women with PCOS.

Lipid panel (total cholesterol, LDL, HDL, triglycerides) assesses cardiovascular risk associated with the metabolic effects of PCOS and tracks response to lifestyle changes.

TSH and thyroid function rule out hypothyroidism as a cause or co-factor for irregular periods and other overlapping symptoms.

AMH (anti-Mullerian hormone) is elevated in PCOS because the increased number of developing follicles produces more of it. AMH is increasingly used to support diagnosis and assess ovarian reserve.

CRP measures systemic inflammation, which is commonly elevated in PCOS and influences disease severity.

For the reproductive hormone markers (testosterone, SHBG, LH, FSH, AMH), your GP can request these through the NHS if PCOS is clinically suspected. Some private home testing providers also offer hormone panels specifically designed for PCOS assessment.

Dietary approaches targeting insulin resistance

Because insulin resistance is central to PCOS in most women, dietary approaches that reduce the insulin demand on the body tend to produce the most meaningful improvements in symptoms. A low-glycaemic dietary pattern, prioritising whole grains, legumes, vegetables, and proteins over refined carbohydrates and ultra-processed foods, reduces the blood sugar and insulin spike after meals. Even a modest reduction in body weight for those carrying excess weight (as little as 5% has been shown in research to improve androgen levels and menstrual regularity). For women at a healthy weight with PCOS, the dietary focus shifts to food quality and micronutrient density rather than calorie restriction.

Resistance training and its effect on androgen and insulin metabolism

Resistance training improves insulin sensitivity directly and has been shown in research to reduce androgen levels in women with PCOS. Muscle tissue acts as a major glucose disposal site, reducing insulin demand. A combination of resistance exercise and moderate aerobic activity appears to produce better hormonal and metabolic outcomes than cardio-only approaches. Tracking HbA1c and triglycerides over 3-6 months gives a measurable way to see whether your exercise pattern is shifting your metabolic biomarkers in the right direction.

Managing stress and cortisol

Chronic stress elevates cortisol, which promotes insulin resistance and can worsen the hormonal picture in PCOS. The adrenal glands also produce androgens, including DHEA-S, and chronic stress can amplify adrenal androgen output. Structured sleep, regular physical activity, and deliberate recovery time have biological effects on cortisol and insulin metabolism that are directly relevant to PCOS management.

Gut microbiome support and inflammation reduction

The gut microbiome influences oestrogen metabolism and systemic inflammation, both relevant to PCOS. A diet rich in fibre from diverse plant sources, fermented foods, and minimal ultra-processed food supports a more diverse microbiome and reduced inflammatory load. Tracking CRP alongside your hormonal markers helps you see whether inflammatory burden is reducing as you make dietary changes.