The Complete PCOS Blood Test Guide: What to Test and What Results Mean | ALIV

A diagnosis of PCOS — or PCOD — in India frequently follows an ultrasound finding of polycystic ovaries. This is the starting point, not the ending point. A complete clinical picture of PCOS requires a blood panel that characterises the hormonal environment, metabolic status, and any nutritional deficiencies contributing to the syndrome. Most patients with a PCOS diagnosis have never had the majority of these tests done — which means they have a label without a mechanism, and a treatment recommendation without a proper clinical basis for it.

The Hormonal Panel

LH and FSH (luteinising hormone and follicle-stimulating hormone): The LH:FSH ratio is informative in PCOS — an elevated ratio (above 2:1, particularly above 3:1) is characteristic of PCOS and reflects the hypothalamic-pituitary dysregulation central to the syndrome. These should be measured on day 2-5 of the menstrual cycle for the most interpretable results.

Total and free testosterone: Elevated total testosterone is present in approximately 60-70% of PCOS patients; free testosterone (the unbound, biologically active fraction) can be elevated when total testosterone is borderline. Both should be measured. The clinical manifestations — acne, hirsutism, scalp hair thinning — may be driven by free testosterone even when total testosterone is within the broad normal range.

DHEA-S (dehydroepiandrosterone sulphate): DHEA-S is the androgen produced predominantly by the adrenal gland rather than the ovaries. In PCOS, a proportion of androgen excess is adrenal in origin. Elevated DHEA-S suggests adrenal androgen contribution to the clinical picture, which has different therapeutic implications from purely ovarian androgen excess.

SHBG (sex hormone-binding globulin): SHBG is produced by the liver and binds free sex hormones in circulation. Insulin resistance suppresses SHBG, increasing free androgen availability. A low SHBG in PCOS is both a marker of insulin resistance and a driver of androgen excess. It is an important piece of the hormonal picture even when total testosterone is not dramatically elevated.

AMH (anti-Mullerian hormone): AMH is produced by ovarian follicles and is a marker of ovarian follicular reserve. In PCOS, AMH is typically elevated — sometimes two to three times above the normal range — reflecting the large number of small antral follicles characteristic of polycystic ovarian morphology. AMH is useful diagnostically and for tracking treatment response; it declines toward normal as PCOS is better managed.

The Metabolic Panel

Fasting insulin and fasting glucose: The single most informative and most commonly omitted test in PCOS assessment. Fasting insulin above 10-12 mU/L is concerning; above 15 is clinically significant insulin resistance in most PCOS patients. HOMA-IR calculated from these values (fasting glucose x fasting insulin / 405) provides a standardised insulin resistance score. See the detailed explanation: PCOS and insulin resistance.

Fasting lipid panel: PCOS is associated with dyslipidaemia — typically elevated triglycerides, low HDL, and elevated small dense LDL (the most atherogenic LDL fraction). A full lipid panel including triglycerides should be part of the initial metabolic workup, as it provides cardiovascular risk context beyond the gynaecological presentation.

Thyroid function (TSH, free T3, free T4): Hypothyroidism can mimic or coexist with PCOS, producing irregular periods, weight difficulty, and fatigue. Screening thyroid function in every PCOS patient prevents misattributing thyroid-driven symptoms to PCOS and vice versa.

Nutritional Deficiencies

Vitamin D: Vitamin D deficiency is extremely prevalent in PCOS patients — rates of 50-80% are reported in studies — and low vitamin D is associated with worse insulin resistance, worse androgen excess, and higher rates of depression in PCOS. Correcting vitamin D deficiency is one of the lowest-risk, highest-return interventions in PCOS management. B12: Important in vegetarian PCOS patients taking metformin (metformin reduces B12 absorption) or with dietary restriction. Ferritin: Particularly important if hair loss is a symptom. See: the full PCOS pillar guide for the comprehensive clinical context.

On which day of my cycle should I do hormonal blood tests?

The optimal timing for hormonal PCOS tests is day 2-5 of the menstrual cycle (counting from the first day of full flow). LH, FSH, testosterone, DHEA-S, and AMH are all most informative in this early follicular window. For patients with very irregular or absent periods, testing can be done at any time with the cycle day noted on the test request; the result interpretation is simply adjusted for the uncertainty of cycle timing.

Can I do PCOS blood tests without a doctor's referral?

In India, most pathology laboratories allow direct access to blood tests without a doctor's referral. You can request an LH, FSH, testosterone, DHEA-S, SHBG, AMH, fasting insulin, fasting glucose, lipid panel, TSH, vitamin D, B12, and ferritin panel directly. Bringing these results to your ALIV or gynaecology consultation means the clinical discussion starts with data rather than assumptions.

My testosterone is "within the normal range" but I have all the PCOS symptoms. Is the test wrong?

Not necessarily — the normal range for testosterone in women is broad, and some women experience significant androgenic symptoms at the upper end of the "normal" range, particularly when SHBG is low (which increases the biologically active free testosterone fraction) or when the ovaries are more sensitive to androgen signalling than average. Checking free testosterone and SHBG alongside total testosterone often reveals an androgen excess pattern that total testosterone alone misses.

How often should I repeat PCOS blood tests?

After the initial comprehensive panel, the key markers to track treatment response are: fasting insulin (to confirm insulin sensitivity is improving), testosterone and SHBG (to confirm androgen excess is reducing), and AMH (to track follicular activity changes). Every six months during active management is a typical monitoring interval; annually once the condition is well-controlled. Tracking the numbers — not just symptoms — provides objective evidence of whether the intervention is working.