PCOS and Blood Tests: Which Hormone Panels Actually Matter
PCOS diagnosis and monitoring involves more than one hormone test. Here's what LH, FSH, testosterone and insulin markers each contribute to the picture.
PCOS (Polycystic Ovary Syndrome) is diagnosed from a combination of symptoms, ultrasound findings and blood work — no single hormone test confirms it alone, which is part of why the lab panel for PCOS can look more complex than a typical checkup.
The hormone ratio doctors often look at
LH (Luteinizing Hormone) and FSH (Follicle Stimulating Hormone) are both pituitary hormones involved in the menstrual cycle. In PCOS, an elevated LH-to-FSH ratio is a commonly observed pattern, though it isn't present in every case and isn't required for diagnosis.
Androgens: testosterone and DHEA-S
Elevated testosterone and DHEA-S (an adrenal androgen) are frequently checked, since excess androgen activity is one of the core features associated with PCOS — connected to symptoms like acne, excess hair growth, and hair thinning.
Insulin resistance markers
Because PCOS is closely linked with insulin resistance for many people, fasting insulin and fasting glucose (sometimes combined into a calculated ratio) are commonly included, even though they're not androgen or reproductive hormones themselves.
Why timing in the cycle matters for testing
Several of these hormones — especially LH, FSH and estrogen — vary meaningfully across the menstrual cycle. Most protocols specify testing on a particular cycle day (often early, around day 2–5) specifically so results are comparable to established reference points.
The bigger picture
Because PCOS presentations vary so widely between individuals, the same panel can look quite different in two people who both carry the diagnosis — which is exactly why blood work here is interpreted alongside symptoms and imaging, not read in isolation.
This is general health information, not medical advice. Always talk to a qualified healthcare professional about your own results.
