PCOS lab work: what the pattern across hormones really says
Anchor biomarkers: Free testosterone, LH/FSH ratio, fasting insulin, SHBG
TL;DR
- •PCOS is a syndrome, not a single lab finding. The diagnosis lives in the *pattern* across androgens (free T, DHEA-S), the LH-to-FSH ratio, fasting insulin, and clinical features — not any one number.
- •Insulin resistance is upstream of the hormone picture for most PCOS patients. Fasting insulin and HOMA-IR are often the most modifiable levers.
- •"Normal testosterone" with high free testosterone is a real pattern. SHBG (sex hormone binding globulin) is the missing piece that makes the math work.
What each marker tells you
| Marker | Reference range | What it means |
|---|---|---|
| Total testosterone | 8 – 60 ng/dL | The total pool. Often "in range" in PCOS despite elevated free fraction. |
| Free testosterone | < 6.4 pg/mL (varies by lab) | The active fraction reaching tissues. Often elevated in PCOS. |
| SHBG (sex hormone binding globulin) | 18 – 144 nmol/L | The protein that binds testosterone. Low SHBG = more free T circulating, even at "normal" total T. Low SHBG itself is a marker of insulin resistance. |
| DHEA-S | 65 – 380 µg/dL | Adrenal androgen. Elevation can indicate adrenal-driven hyperandrogenism. |
| LH (luteinizing hormone) | 5 – 25 mIU/mL (varies by cycle phase) | Elevated in PCOS; often paired with normal-to-low FSH. |
| FSH (follicle stimulating hormone) | 3 – 20 mIU/mL (varies by cycle phase) | The denominator of the LH:FSH ratio. |
| LH:FSH ratio | ≈ 1:1 in normal cycling · > 2:1 suggestive of PCOS | A classic PCOS pattern, though it can be normal in mild PCOS. |
| Fasting insulin | < 10 µIU/mL (optimal < 5) | Often elevated in PCOS. The metabolic engine behind the hormonal picture. |
| HOMA-IR | < 1.5 optimal | Insulin resistance index. > 2.5 suggests clear insulin resistance. |
| Anti-Müllerian hormone (AMH) | 1.0 – 3.5 ng/mL (reproductive age) | Often elevated in PCOS. Reflects ovarian follicle count. |
| Free T4 + TSH | normal | Thyroid dysfunction overlaps and mimics PCOS — always worth ruling out. |
| Prolactin | < 25 ng/mL | Elevated prolactin causes PCOS-like symptoms; always worth ruling out. |
Three real patterns Phi has seen
Example patterns · synthetic data drawn from Phi's scenario library. Not real patient records.
Pattern 1 — Classic insulin-resistant PCOS.
Total T 48 (high-normal). Free T 8.2 (elevated). SHBG 22 (low). DHEA-S 195. LH 22. FSH 7. LH:FSH 3.1. Fasting insulin 19. HOMA-IR 4.5. The classic case: insulin resistance is suppressing SHBG, freeing more testosterone, fueling androgenic symptoms (acne, hirsutism, irregular cycles). Lifestyle work targeting insulin resistance (resistance training, walking after meals, protein-priority eating, sleep) typically moves the entire pattern in the right direction over 3–6 months.
Example pattern · synthetic data
Pattern 2 — Lean PCOS / adrenal-dominant pattern.
Total T 55. Free T 7.4. SHBG 78 (normal). DHEA-S 385 (high). LH 14. FSH 10. LH:FSH 1.4 (normal). Fasting insulin 6 (normal). HOMA-IR 1.2 (normal). BMI 22 (normal weight). This patient has hyperandrogenism without classic insulin resistance — the androgen excess is driven more by the adrenals. Often presents with later age of onset, prominent stress sensitivity, and may respond better to stress-management and adrenal-supportive approaches than to insulin-sensitizing strategies.
Example pattern · synthetic data
Pattern 3 — "PCOS-treated" but still symptomatic.
On combined oral contraceptive 3 years. Total T 18 (suppressed). Free T 2.1 (suppressed). SHBG 110 (elevated by OCP). DHEA-S 175. LH 4. FSH 3. Fasting insulin 16 (still high). HOMA-IR 3.8 (still high). The contraceptive has masked the androgen picture, and the patient feels her acne is better. But the *underlying* insulin resistance is unchanged — and metabolic risk is the same as before. The Phi read: hormonal symptoms managed, metabolic root cause unaddressed.
Example pattern · synthetic data
Questions to bring to your doctor
- Have we measured free testosterone (not just total) and SHBG?
- What's my fasting insulin, and has HOMA-IR been calculated?
- Have we ruled out thyroid dysfunction and elevated prolactin as PCOS mimics?
- If I'm not currently trying to conceive, what's our plan for the underlying insulin resistance — beyond contraceptive symptom management?
- Should I be screened for sleep apnea? It's underdiagnosed in PCOS and worsens insulin resistance.
- Where do my androgens trend over the next 6 months if I focus on lifestyle work?
- Is my AMH or follicle count concerning for fertility planning, given my age and goals?
What Phi adds beyond a single number
PCOS lives in the relationship between hormones, not in any one of them. Phi reads the full panel — androgens + binding globulin + LH/FSH + insulin + thyroid + prolactin — together, and tracks how each marker moves across panels over months. The integrated picture helps surface whether you're metabolically PCOS (driven by insulin resistance), adrenally PCOS, or have a mixed picture; whether contraceptive treatment is masking metabolic risk; and which specific lifestyle levers your numbers are actually responding to.
Upload your most recent lab report. Phi will pull out every PCOS-relevant marker, compare them against optimal (not just reference) ranges, flag the pattern, and tell you what to ask at your next appointment.
Frequently asked questions
Can I have PCOS with normal testosterone?
Yes. The diagnostic criteria (Rotterdam) require any two of: hyperandrogenism (clinical or biochemical), oligo-/anovulation, and polycystic ovarian morphology. Some patients have normal total T but elevated *free* T due to low SHBG, or hyperandrogenism that's primarily clinical (hirsutism, acne) without dramatic lab elevation.
What's the difference between PCOS and "polycystic ovaries"?
Polycystic-appearing ovaries on ultrasound (many small follicles) can occur in healthy women — up to 20–30% in some studies. PCOS the syndrome requires additional findings beyond ovarian morphology.
Is metformin the right treatment for me?
Metformin is well-supported for PCOS patients with documented insulin resistance, especially when fertility is a goal. It's not appropriate for every PCOS patient. Many lean / adrenal-dominant PCOS patients don't benefit from metformin.
Will birth control "fix" my PCOS?
Combined oral contraceptives manage *symptoms* (regular bleeding, acne, hirsutism) by suppressing ovarian androgen production. They don't address the underlying insulin resistance or hormonal patterns. They're a useful tool for symptom management when fertility isn't immediate, but they aren't a cure.
Can lifestyle change actually move PCOS labs?
Yes — often substantially. Resistance training, dietary protein priority, post-meal walking, and adequate sleep can lower fasting insulin, raise SHBG, lower free testosterone, and restore cycles in many insulin-resistant PCOS patients within 3–6 months. The change is measurable across panels.
Is PCOS lifelong?
The metabolic and hormonal patterns persist, but symptom severity and lab values can change substantially with intervention. Post-menopause, PCOS effectively transitions to a metabolic-risk profile (higher T2D and cardiovascular risk) that needs continued attention even as reproductive features fade.
What about inositol — does it actually work?
Myo-inositol + d-chiro-inositol (in the 40:1 ratio) has reasonable RCT evidence for improving insulin sensitivity, cycle regularity, and ovulation in PCOS. It's not first-line for everyone but is one of the better-supported supplements in this space. Quality varies — talk to a clinician about specific products.
Am I going to have trouble conceiving?
Many women with PCOS conceive without intervention. Others need ovulation induction (letrozole or clomiphene) or more. The combination of AMH, age, cycle regularity, and metabolic markers determines individual fertility planning — not PCOS as a label.
References
All citations verified against PubMed / publisher of record 2026-05-25.
- 1.Rotterdam ESHRE/ASRM-Sponsored PCOS Consensus Workshop Group. (2004). Revised 2003 consensus on diagnostic criteria and long-term health risks related to polycystic ovary syndrome (PCOS). Human Reproduction. 19(1):41-47. — The Rotterdam criteria: PCOS requires any 2 of (1) oligo-/anovulation, (2) clinical or biochemical hyperandrogenism, (3) polycystic ovarian morphology — plus exclusion of other causes. Co-published in Fertil Steril 81(1):19-25.PubMed →DOI →
- 2.Teede HJ, Tay CT, Laven JJE, et al. (2023). Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. Journal of Clinical Endocrinology & Metabolism. 108(10):2447-2469. — Current international consensus for PCOS diagnosis (including AMH as alternative to ultrasound in adults), workup, metabolic and cardiovascular surveillance, fertility management, and lifestyle. Basis for the AMH-as-alternative framing.PubMed →DOI →
- 3.Bhasin S, Brito JP, Cunningham GR, et al. (2018). Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology & Metabolism. 103(5):1715-1744. — Reference for the Vermeulen-calculated-free-T methodology framing, also relevant to total + free testosterone interpretation in women per the same calculation principles.PubMed →DOI →
- 4.Vermeulen A, Verdonck L, Kaufman JM. (1999). A critical evaluation of simple methods for the estimation of free testosterone in serum. Journal of Clinical Endocrinology & Metabolism. 84(10):3666-3672. — The Vermeulen formula for calculating free testosterone from total T + SHBG + albumin; basis for the "total T + SHBG together is the right read" framing.PubMed →DOI →
- 5.Unfer V, Facchinetti F, Orrù B, Giordani B, Nestler J. (2017). Myo-inositol effects in women with PCOS: a meta-analysis of randomized controlled trials. Endocrine Connections. 6(8):647-658. — Meta-analysis of 9 RCTs of myo-inositol alone or combined with d-chiro-inositol in PCOS; basis for the inositol-evidence framing in the FAQ.PubMed →DOI →
Every link above opens the PubMed abstract or publisher's DOI landing page in a new tab. All citations verified vs PubMed / publisher of record 2026-05-26.
By Steve Pinedo
Co-founder, Phi Longevity
Last updated: 2026-05-26
Steve Pinedo is the Co-founder of Phi Longevity, the AI application that turns a confusing stack of lab reports, wearable data, and clinical notes into a single, integrated picture of your health. He started Phi Longevity to make proactive health and wellness far easier to achieve. He realized how difficult it was for clients to manage their own care, records and coordination so he assembled a comprehensive M.D. led clinical team behind the platform, packaging the proactive-care experience that delivered measurable outcomes (lower triglycerides, reduced body fat, improved LDL, balanced hormones, relief from long-running autoimmune conditions) for any patient with a complicated lab to use now with an application. More about Phi →