Your gynaecologist has ordered a PCOS panel and the results are back: numbers like "LH: 14.2 IU/L," "AMH: 6.8 ng/mL," "testosterone: 68 ng/dL," and "HOMA-IR: 3.4" are staring at you. Maybe some are flagged, maybe none are — yet the pattern across all of them together is what actually tells the story of PCOS. Understanding what each marker means individually, and how they interact, is the difference between leaving your appointment confused and leaving with a clear treatment plan.
Polycystic Ovary Syndrome (PCOS) affects an estimated 8-13% of reproductive-age women in India by strict diagnostic criteria — but epidemiological studies in Indian populations report rates as high as 22% depending on the criteria used and the population screened. What makes this more alarming: approximately 70% of affected women are undiagnosed. PCOS is not just a fertility issue; it carries significant metabolic risk — higher rates of type 2 diabetes, cardiovascular disease, endometrial cancer, and mental health conditions across a lifetime. Understanding your blood test results is the first step toward managing those risks.
How PCOS Is Diagnosed: The Rotterdam Criteria
Before interpreting individual markers, it helps to understand the framework doctors use to diagnose PCOS. The internationally accepted Rotterdam criteria (2003, widely adopted in India) require at least two of three features:
- Oligomenorrhoea or anovulation (infrequent or absent periods, typically fewer than 8 cycles per year)
- Clinical or biochemical hyperandrogenism (excess androgens — acne, hirsutism, hair loss — or elevated testosterone/DHEA-S on blood test)
- Polycystic ovarian morphology on ultrasound (12 or more follicles measuring 2-9 mm, or ovarian volume above 10 mL)
Blood tests do not independently diagnose PCOS — they contribute to criterion 2 (biochemical hyperandrogenism) and rule out other conditions that mimic PCOS. This is important because a "PCOS blood test panel" will often appear borderline or within normal ranges in women who nonetheless have PCOS by Rotterdam criteria — particularly those with the "mild" phenotype (regular cycles + ultrasound findings).
Marker 1: LH and FSH — The Ratio That Matters More Than Individual Values
Luteinising Hormone (LH) and Follicle-Stimulating Hormone (FSH) are pituitary hormones that orchestrate the ovarian cycle. They must be tested on days 2-5 of the menstrual cycle (day 1 = first day of full flow) for meaningful interpretation.
In PCOS, the hypothalamic-pituitary axis is dysregulated: the pulsatile release of GnRH (the master hormone driving LH and FSH) becomes faster and more frequent. This preferentially stimulates LH production while relatively suppressing FSH. The result is a characteristic pattern of elevated LH with relatively normal FSH.
| Marker | Normal Range (Day 2-3) | PCOS Pattern |
|---|---|---|
| FSH | 3.0 – 10.0 IU/L | Usually normal or low-normal |
| LH | 2.0 – 12.0 IU/L | Often elevated (10-20+ IU/L in classic PCOS) |
| LH:FSH Ratio | <2:1 | >2:1 suggestive; >3:1 strongly suggestive of PCOS |
Important caveat: LH:FSH ratio is a supportive finding, not a diagnostic criterion. Up to 40% of women with PCOS have a normal LH:FSH ratio, particularly those with obesity (which suppresses LH). Conversely, women who are thin and stressed may have transiently elevated LH without PCOS. The ratio must be interpreted alongside other markers and symptoms.
Marker 2: AMH — Elevated in PCOS, Not Reduced
Anti-Müllerian Hormone (AMH) is perhaps the most misunderstood marker in PCOS. Many women with PCOS fear their AMH is "too low" (a concern relevant to diminished ovarian reserve), when in fact PCOS characteristically produces elevated AMH.
In PCOS, the ovaries contain an abnormally large number of small arrested antral follicles — each one secreting AMH. The result is AMH values often 2-3 times higher than age-matched women without PCOS. Studies from Indian IVF centres find mean AMH values of 7-10 ng/mL in Indian women with PCOS.
| AMH Level (ng/mL) | Interpretation in Women Under 35 |
|---|---|
| <1.5 | Low ovarian reserve — PCOS unlikely (unless on OCP) |
| 1.5 – 4.5 | Normal range for age |
| 4.5 – 7.0 | Elevated — consistent with PCOS; consider full workup |
| >7.0 | Significantly elevated — strongly associated with PCOS phenotype |
Some researchers have proposed adding AMH to the Rotterdam criteria as a fourth option in place of ultrasound (since AMH correlates well with follicle count), but this has not yet been formally adopted in Indian or international guidelines.
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Marker 3: Total Testosterone and Why "Normal" Can Still Mean Excess
Testosterone in women is produced by the ovaries and adrenal glands. In PCOS, the ovaries overproduce testosterone due to elevated LH stimulation and insulin-driven androgen synthesis. The reference range for total testosterone in women on most Indian lab reports is 20-70 ng/dL, with some labs showing up to 80 ng/dL as "normal."
The clinically important nuance: even a testosterone result at the high end of the normal range — say 62 ng/dL — may represent biochemical hyperandrogenism if SHBG is low. SHBG (Sex Hormone Binding Globulin) is the protein that binds testosterone in circulation, rendering it biologically inactive. When SHBG is low (driven by insulin resistance and obesity), more testosterone is "free" and biologically active, causing androgenic symptoms like acne, hirsutism, and scalp hair thinning — even when total testosterone appears normal.
| Marker | Normal Range (Women) | PCOS Pattern |
|---|---|---|
| Total Testosterone | 20 – 70 ng/dL | Often high-normal or mildly elevated (60-90 ng/dL) |
| SHBG | 40 – 120 nmol/L | Often low (<30-40 nmol/L) in PCOS, especially with insulin resistance |
| Free Androgen Index (FAI) | <5.0 | FAI = (Total T ÷ SHBG) × 100; >5.0 = biochemical hyperandrogenism |
If your total testosterone is within range but you have clinical features of androgen excess, specifically request SHBG and calculate Free Androgen Index. This is frequently the missing piece in PCOS biochemistry that a basic panel misses.
Marker 4: DHEA-S — The Adrenal Androgen
Dehydroepiandrosterone Sulphate (DHEA-S) is the primary androgen produced by the adrenal glands (as opposed to testosterone, which is mainly ovarian in PCOS). About 20-30% of women with PCOS have elevated DHEA-S, indicating adrenal contribution to their androgen excess — an important distinction because "adrenal PCOS" may respond differently to treatment.
| Age Group | Normal DHEA-S Range (Women, µg/dL) |
|---|---|
| 18 – 29 | 65 – 380 |
| 30 – 39 | 45 – 270 |
| 40 – 49 | 32 – 240 |
Very high DHEA-S (above 700 µg/dL) is unusual for PCOS and should prompt investigation for adrenal tumour or congenital adrenal hyperplasia (CAH) — which can mimic PCOS clinically but requires different management. Moderately elevated DHEA-S (above the age-specific normal but below 700 µg/dL) is common in PCOS and responds to lifestyle interventions and metformin.
Marker 5: Fasting Insulin and HOMA-IR — The Most Undertested Marker
Insulin resistance is present in 50-70% of women with PCOS in India — and in up to 80% of those who are overweight. Insulin directly stimulates ovarian androgen production, increases LH pulse frequency, and suppresses SHBG. In essence, insulin resistance is often the upstream driver of the entire PCOS hormonal cascade. Treating insulin resistance is therefore one of the most effective interventions across all PCOS phenotypes.
Yet fasting insulin is almost never included in a standard PCOS panel and is not routinely ordered in India. A normal fasting glucose does not rule out insulin resistance — the hallmark is a normal glucose maintained only by excessive insulin secretion.
Calculating HOMA-IR:
HOMA-IR = Fasting Insulin (µIU/mL) × Fasting Glucose (mmol/L) ÷ 22.5
To convert glucose from mg/dL to mmol/L: divide by 18.
Example: Fasting insulin 16 µIU/mL, fasting glucose 98 mg/dL (5.44 mmol/L) → HOMA-IR = 16 × 5.44 ÷ 22.5 = 3.87
| HOMA-IR Value | Interpretation |
|---|---|
| <1.5 | Insulin sensitive — ideal |
| 1.5 – 2.5 | Early insulin resistance — lifestyle intervention |
| 2.5 – 3.5 | Moderate insulin resistance — consider metformin or inositol |
| >3.5 | Significant insulin resistance — high metabolic and cardiovascular risk |
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Marker 6: Prolactin — To Rule Out Hyperprolactinemia
Elevated prolactin (hyperprolactinemia) causes irregular periods, anovulation, and galactorrhoea (spontaneous milk production) — symptoms that closely overlap with PCOS. Prolactin should be tested in every woman presenting with PCOS symptoms to exclude this diagnosis before attributing symptoms to PCOS.
| Prolactin Level | Interpretation |
|---|---|
| <25 ng/mL (women) | Normal |
| 25 – 100 ng/mL | Mild elevation — repeat fasting; stress and recent examination can raise it transiently |
| >100 ng/mL | Significant hyperprolactinemia — MRI pituitary to exclude prolactinoma |
Note: prolactin can be mildly elevated in PCOS itself (approximately 30% of PCOS women have prolactin in the 25-50 ng/mL range). The clinically important elevation is above 100 ng/mL, where a pituitary adenoma (prolactinoma) needs to be excluded.
Marker 7: TSH — Thyroid Disorders That Mimic PCOS
Hypothyroidism causes irregular periods, weight gain, hair loss, fatigue, and — when severe — elevated prolactin. These features overlap so extensively with PCOS that thyroid status must be evaluated in every woman presenting with suspected PCOS. TSH above 4.0-5.0 mIU/L suggests hypothyroidism; TSH above 2.5 mIU/L with symptoms may represent subclinical hypothyroidism warranting evaluation. Hyperthyroidism can also disrupt cycles. Autoimmune thyroid disease (Hashimoto's thyroiditis) is significantly more common in women with PCOS than in the general population.
What "Mild" vs. "Classic" PCOS Means Biochemically
PCOS exists on a spectrum. The Rotterdam criteria allow four different phenotypes depending on which two of three features are present:
- Classic PCOS (Phenotype A — most severe): Irregular cycles + hyperandrogenism + polycystic ovaries. Highest LH, highest testosterone, most insulin resistance. Blood tests typically show all markers abnormal.
- Phenotype B: Irregular cycles + hyperandrogenism, no polycystic morphology. Blood tests show androgen and LH abnormalities; AMH may be less dramatically elevated.
- Phenotype C: Hyperandrogenism + polycystic morphology, but regular cycles. Blood tests often mildly abnormal. High AMH but LH:FSH ratio often normal.
- Phenotype D (mildest): Irregular cycles + polycystic morphology, no hyperandrogenism. Normal androgens and SHBG. Diagnosis relies more on ultrasound and cycle history.
Understanding your PCOS phenotype determines which interventions matter most. Classic PCOS with insulin resistance responds best to metformin, inositol, and lifestyle modification. Phenotype D may need only cycle monitoring and lifestyle changes.
Treatment Approaches Based on Your Results
PCOS management is personalised to the dominant pathway:
- High HOMA-IR (>2.5): Low glycaemic index diet, reduce refined carbohydrates, increase protein and fibre, 150+ minutes/week aerobic exercise plus resistance training. Metformin 500-1500 mg/day (prescribed by doctor). Myo-inositol 2-4g/day has strong evidence for improving insulin sensitivity and ovarian function with fewer side effects than metformin.
- Elevated androgens: Hormonal contraception (combined oral contraceptive pill) suppresses LH and increases SHBG, reducing free testosterone — effective for acne and hirsutism. Spironolactone 50-100 mg/day is an androgen blocker used in India for severe androgenic features.
- Irregular cycles / anovulation: Progesterone challenge to induce withdrawal bleeds, clomiphene citrate or letrozole to induce ovulation if trying to conceive.
- Indian lifestyle context: Sedentary work culture (6-8 hours sitting per day), high refined carbohydrate diet (white rice, maida-based products, biscuits, chai with 2 teaspoons sugar 3x/day), chronic work stress — all of these worsen insulin resistance and PCOS. Even 30 minutes of walking after the main meal of the day measurably improves post-meal insulin spikes.
Frequently Asked Questions
What LH:FSH ratio confirms PCOS?
A LH:FSH ratio above 2:1 is considered abnormal, and a ratio above 3:1 is strongly suggestive of PCOS. However, PCOS cannot be diagnosed from LH:FSH ratio alone. The Rotterdam criteria require at least two of three features: irregular cycles, clinical or biochemical hyperandrogenism, or polycystic ovaries on ultrasound. LH:FSH ratio supports the diagnosis but is not one of the three Rotterdam criteria. Up to 40% of women with PCOS have a normal ratio, particularly those with obesity.
Can PCOS be present with normal testosterone levels?
Yes. Approximately 30-40% of women with PCOS by Rotterdam criteria have normal total testosterone. PCOS drives down SHBG levels, meaning more testosterone is biologically active (free) even when total testosterone appears normal. Requesting free testosterone or calculating Free Androgen Index (Total Testosterone ÷ SHBG × 100; abnormal above 5.0) is necessary to detect biochemical hyperandrogenism in these cases. Clinical features of androgen excess (acne, hirsutism, scalp hair thinning) in the presence of normal total testosterone are not "in your head" — they reflect elevated free androgens.
How do I calculate HOMA-IR from my blood test?
HOMA-IR = Fasting Insulin (µIU/mL) × Fasting Glucose (mmol/L) ÷ 22.5. To convert fasting glucose from mg/dL to mmol/L, divide by 18. For example: fasting insulin 14 µIU/mL, fasting glucose 95 mg/dL (5.28 mmol/L) → HOMA-IR = 14 × 5.28 ÷ 22.5 = 3.28. A HOMA-IR above 2.5 indicates insulin resistance in most Indian populations; above 3.5 is significant insulin resistance associated with higher metabolic and cardiovascular risk. Fasting insulin must be ordered separately — it is not included in a standard blood sugar panel.
What is a normal AMH level for PCOS?
In women with PCOS, AMH is characteristically elevated rather than low — typically 4.5-10+ ng/mL — because polycystic ovaries contain far more small antral follicles than normal, each secreting AMH. An AMH above 4.5-5.0 ng/mL in a woman under 35 is considered elevated and supportive of PCOS evaluation. Indian women with PCOS tend to have higher AMH than Western PCOS populations, with studies from Indian IVF centres reporting average values of 7-10 ng/mL. High AMH does not mean infertility — it means the ovaries have many follicles but they are not ovulating normally.
Does PCOS go away with treatment?
PCOS is a lifelong hormonal condition that cannot be "cured" in the conventional sense, but its symptoms and metabolic consequences can be very well controlled. Lifestyle changes — reducing refined carbohydrate intake, increasing physical activity, and achieving even 5-10% weight loss if overweight — can restore regular ovulation in many women. Myo-inositol (2-4g/day) improves insulin sensitivity and androgen levels with a strong evidence base. Metformin is prescribed for significant insulin resistance. Regular monitoring of metabolic markers (HOMA-IR, lipid panel, HbA1c) throughout adulthood is important to prevent the long-term complications of PCOS including type 2 diabetes and cardiovascular disease.