PCOS: Diagnosis, Blood Markers, and Evidence-Based Management

Polycystic Ovary Syndrome (PCOS) is one of the most common endocrine disorders affecting women of reproductive age in the UK. Despite its prevalence, it remains widely misunderstood and frequently underdiagnosed. The condition is characterised by a complex interplay of hormonal imbalances, metabolic issues, and reproductive challenges.

As a clinician, I often see patients who have struggled for years with unexplained weight gain, irregular menstrual cycles, adult acne, or excessive hair growth (hirsutism). These symptoms can be deeply distressing, but they are not simply "part of being a woman." They are clinical signs of an underlying hormonal disruption that requires precise investigation.

The Rotterdam Criteria: How PCOS is Diagnosed

The diagnosis of PCOS is not based on a single test but rather a combination of clinical signs and biochemical markers. In the UK, we generally follow the Rotterdam Criteria, which requires the presence of at least two of the following three features:

• Oligo-ovulation or anovulation: Irregular or absent menstrual periods.
• Clinical or biochemical hyperandrogenism: Physical signs of excess male hormones (like acne or hirsutism) or elevated androgen levels in blood tests.
• Polycystic ovaries: Visible on an ultrasound scan (though the name is misleading—these are actually small, undeveloped follicles, not true cysts).

Crucially, a diagnosis can only be made after excluding other conditions that mimic PCOS, such as thyroid dysfunction, congenital adrenal hyperplasia, or hyperprolactinemia. This is where comprehensive blood testing becomes essential.

Key Blood Markers for PCOS

A standard hormone panel is often insufficient to capture the full metabolic and endocrine picture of PCOS. A thorough investigation should include:

1. Testosterone and Free Androgen Index (FAI)

Elevated testosterone is a hallmark of PCOS. However, measuring Total Testosterone alone is not enough. We must also look at Sex Hormone Binding Globulin (SHBG). In PCOS, insulin resistance often lowers SHBG levels. Since SHBG binds to testosterone, lower SHBG means more "free," active testosterone circulating in the blood, driving symptoms like acne and hair growth. The Free Androgen Index (FAI) calculates this ratio.

2. Luteinising Hormone (LH) and Follicle-Stimulating Hormone (FSH)

In a typical menstrual cycle, FSH stimulates follicle development, and a surge in LH triggers ovulation. In many women with PCOS, the baseline level of LH is abnormally high compared to FSH (often a ratio of 2:1 or 3:1). This elevated LH stimulates the ovaries to produce excess androgens and disrupts normal ovulation.

3. Insulin and HbA1c

Metabolic dysfunction is deeply intertwined with PCOS. Up to 70% of women with PCOS have some degree of insulin resistance, regardless of their body weight. High insulin levels directly stimulate the ovaries to produce more testosterone and further suppress SHBG production. Testing HbA1c (average blood sugar over three months) and fasting insulin is critical for identifying metabolic risk early.

4. Anti-Müllerian Hormone (AMH)

AMH is produced by the small follicles in the ovaries. Because women with PCOS typically have a high number of these small, undeveloped follicles, their AMH levels are often significantly elevated—sometimes two to three times higher than the normal range for their age.

Evidence-Based Management

There is no "cure" for PCOS, but it is highly manageable. Treatment must be tailored to the individual's specific symptoms and biochemical profile:

• Metabolic Management: If insulin resistance is present, dietary modifications (focusing on low-glycemic index foods), regular exercise, and medications like Metformin or Inositol supplements can dramatically improve both metabolic and reproductive symptoms.
• Hormonal Regulation: For those not trying to conceive, combined oral contraceptives can regulate the menstrual cycle, lower LH levels, and increase SHBG, thereby reducing free testosterone.
• Targeted Supplementation: Evidence supports the use of specific supplements, such as Vitamin D (which is often deficient in PCOS patients and linked to insulin resistance) and Omega-3 fatty acids to reduce systemic inflammation.

Understanding your specific hormonal and metabolic baseline is the first step in taking control of PCOS. With accurate data, you and your healthcare provider can develop a targeted, effective management plan.

Medical References

1. National Institute for Health and Care Excellence (NICE). (2018). Polycystic ovary syndrome. Clinical Knowledge Summaries.
2. Teede, H. J., et al. (2018). Recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome. Clinical Endocrinology, 89(3), 251-268.
3. Conway, P., et al. (2014). The polycystic ovary syndrome: a position statement from the European Society of Endocrinology. European Journal of Endocrinology, 171(4), P1-P29.