PCOD / PCOS: Understanding Your Hormone Tests

What is PCOD/PCOS?

PCOS (Polycystic Ovary Syndrome) is a hormonal disorder where the ovaries produce excess androgens (male hormones), causing irregular periods, excess facial/body hair (hirsutism), acne, hair thinning and difficulty conceiving. It is also strongly linked to insulin resistance, weight gain and long-term risk of Type 2 diabetes and heart disease. PCOD (Polycystic Ovarian Disease) is an older term often used interchangeably, though technically they're slightly different.

Blood Tests Used in PCOS Diagnosis

What does a high LH:FSH ratio mean in PCOS?

What does high AMH mean?

Questions to ask your doctor

• Do I have insulin resistance and should I start metformin?
• Do I need a pelvic ultrasound to count follicles?
• Is my PCOS affecting my fertility?
• What lifestyle changes will have the most impact on my hormone levels?

References

The clinical information on this page is drawn from peer-reviewed sources indexed by the US National Library of Medicine. Links go to the source so you can read it yourself.

1. Hirsutism. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK470417

References

Sources cited on this page. PubMed links open the original abstract.

1. Teede HJ, Misso ML, Costello MF, et al. Recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome. Hum Reprod. 2018;33(9):1602–1618. PMID 30011835 · doi:10.1093/humrep/dey256

The PCOS diagnostic criteria – Rotterdam consensus

Polycystic ovary syndrome (PCOS) is diagnosed when at least two of three Rotterdam criteria are met:

1. Oligo- or anovulation (infrequent or absent ovulation – causing irregular or absent periods)
2. Clinical or biochemical signs of hyperandrogenism (excess androgens: acne, hirsutism, or elevated testosterone/DHEAS on blood tests)
3. Polycystic ovaries on ultrasound (12 or more follicles measuring 2–9 mm in at least one ovary, or ovarian volume above 10 mL)

Importantly, the ultrasound finding of "polycystic-looking ovaries" alone is found in 20–30% of reproductively aged women without PCOS – it is the combination with irregular cycles or androgen excess that makes the diagnosis. The Rotterdam criteria specifically exclude other causes of hyperandrogenism (congenital adrenal hyperplasia – measured by 17-OHP, thyroid disease, and Cushing's syndrome) before PCOS is confirmed.

Blood tests in PCOS investigation

• LH:FSH ratio: In PCOS, LH is characteristically elevated relative to FSH – a ratio above 2:1 (often above 3:1) is a classic finding, caused by the abnormal GnRH pulsatility that drives excess LH secretion. However, the ratio is not always elevated and should not be used as the sole diagnostic criterion.
• Total testosterone and free androgen index (FAI): Testosterone (free or total) is elevated in 60–80% of women with PCOS. Severely elevated testosterone (above 5 nmol/L in a woman) suggests a testosterone-secreting ovarian or adrenal tumour – this warrants further imaging, not PCOS treatment.
• DHEAS: Elevated in approximately 50% of PCOS – reflects adrenal androgen production. Very high DHEAS (above 10–12 µmol/L) suggests an adrenal source (adrenal tumour or congenital adrenal hyperplasia) rather than PCOS.
• 17-hydroxyprogesterone (17-OHP): Taken early morning; elevated in non-classic congenital adrenal hyperplasia (CAH), which closely mimics PCOS and must be excluded.
• Prolactin: Mildly elevated in some PCOS cases; markedly elevated prolactin suggests a prolactinoma causing secondary amenorrhoea and must be excluded before attributing symptoms to PCOS.
• HbA1c and fasting insulin: PCOS carries a significantly increased risk of type 2 diabetes – 5–10 times higher than the general population. Annual HbA1c is recommended. Fasting insulin (though not standardised) quantifies insulin resistance.