A PCOS diagnosis often comes with very little investigation involving more thorough PCOS lab tests. A doctor notes irregular periods and elevated androgens, orders a pelvic ultrasound, and concludes: PCOS (or more recently, PMOS). Here’s a birth control prescription.
That approach identifies the diagnosis but does nothing to characterize the underlying metabolic and hormonal drivers, information that is essential for actually managing the condition rather than masking it.
Knowing which PCOS lab tests to ask for, what they measure, and what the results mean gives you real leverage in your own care.
How PCOS or PMOS Is Currently Diagnosed
The most widely used diagnostic criteria are the Rotterdam criteria (2003), which require only 2 of the following 3:
- Oligo-ovulation or anovulation (you may see this as irregular or absent periods, but you can have irregular ovulation and regular periods)
- Clinical or biochemical hyperandrogenism (excess androgens on blood work, or signs like acne, hirsutism, hair thinning)
- Polycystic ovarian morphology on ultrasound (12 or more follicles 2-9 mm in diameter per ovary, or ovarian volume >10 mL)
This means a person can receive a PCOS diagnosis without ever having elevated androgens on a blood test (if they have irregular cycles and polycystic morphology). It also means someone can have PCOS without polycystic-appearing ovaries (if they have signs or tests of high androgens and irregular ovulation).
The diagnosis tells you what, not why. The PCOS lab tests below tell you why, and that’s what drives treatment.
The Essential PCOS Lab Tests Panel
Androgens
Total testosterone: The most common measure, but it has limitations. Total testosterone includes both bound (inactive) and unbound (active) forms. The range that the lab supplies to your doctor for testosterone in women is too wide. Symptoms of PMOS or PCOS start to appear once the level is greater than 1.0 nmol/L.
Free testosterone: More clinically meaningful than total in many cases. It reflects the androgen actually available to tissues. Free testosterone can be within range even when total is elevated, or vice versa.
SHBG (sex hormone-binding globulin): Not an androgen, but this is the protein that binds and inactivates testosterone. Low SHBG (driven by insulin resistance and elevated androgens) allows more free testosterone to circulate. SHBG is an important part of interpreting the androgen picture.
DHEA-S (dehydroepiandrosterone sulphate): An adrenal androgen. While it is weaker than testosterone, when elevated, it suggests a significant adrenal contribution to androgen excess. This is relevant for treatment targeting.
Androstenedione: Another precursor androgen produced by both the adrenal glands and ovaries. Useful when total testosterone is normal but symptoms suggest hyperandrogenism.
What to note: Many standard labs don’t automatically include free testosterone or androstenedione. You may need to request these specifically.
Insulin and Glucose
Fasting insulin: One of the most important and most frequently omitted tests in PCOS lab tests. A fasting insulin level reflects the baseline insulin demand required to maintain normal glucose. This is a direct window into insulin resistance.
Many women with PCOS (or PMOS) have completely normal fasting glucose but significantly elevated fasting insulin. Without measuring the insulin level, insulin resistance is invisible. As with testosterone, the “normal” range is too wide. Optimal fasting insulin is less than 70 pmol/L (not < 174 as the lab range indicates).
Fasting glucose: Necessary but insufficient on its own. A normal fasting glucose level does not rule out insulin resistance. It will only register as abnormal once you are well on your way to being diabetic. We would rather catch insulin resistance before that.
HOMA-IR (Homeostatic Model Assessment of Insulin Resistance): Calculated from fasting insulin and fasting glucose:
HOMA-IR = [Fasting Glucose (mmol/L) x Fasting Insulin (pmol/L)]/135
A HOMA-IR above 2.0-2.5 suggests insulin resistance. Above 3.0 is significant. Context and trend matter. HOMA-IR should be retested after intervention to track progress.
HbA1c (glycated hemoglobin): Reflects average blood glucose over 2-3 months. Useful for ruling out pre-diabetes and diabetes. Less sensitive than fasting insulin for detecting early insulin resistance, but an important part of the picture. The ideal for this number is around 5.0.
2-hour oral glucose tolerance test (OGTT) with insulin: The most sensitive method for detecting glucose dysregulation. Measures glucose and insulin response at fasting, 1 hour, and 2 hours after a 75g glucose load. Identifies patterns (e.g., normal fasting glucose but exaggerated insulin response at 1 hour) that fasting values miss. Not routinely ordered but highly informative in PCOS.
Gonadotropins
LH (luteinizing hormone) and FSH (follicle-stimulating hormone): Both are measured on days 2–4 of the menstrual cycle (early follicular phase). In PCOS, LH is characteristically elevated relative to FSH, an LH:FSH ratio >2:1 is a classic feature, though not present in all PCOS phenotypes.
Elevated LH levels drive theca cell androgen production and contribute to follicular arrest. This ratio matters for understanding the hormonal environment in which the ovaries are working.
Note: For women with irregular or absent cycles, timing may be less straightforward. A random LH and FSH can still be informative. Discuss the timing of PCOS lab tests with your provider.
AMH (Anti-Müllerian Hormone)
AMH is produced by ovarian granulosa cells and reflects the total follicular pool. It’s the best available marker of ovarian reserve. In PCOS, AMH is typically elevated (2-4 times higher than in women without PCOS), reflecting the large number of arrested small follicles.
AMH is useful as one of your PCOS lab tests to:
- Support the diagnosis (elevated AMH can substitute for ultrasound criteria in the current diagnostic framework)
- Assess ovarian reserve in women who are trying to conceive
- Track response to treatment over time
Thyroid
TSH (thyroid-stimulating hormone): Thyroid dysfunction is a common comorbidity in women with PCOS and can independently cause irregular periods, weight changes, and fatigue, overlapping significantly with PCOS symptoms.
TSH alone is often insufficient. A more complete thyroid panel as part of your PCOS lab tests includes:
Free T4 and Free T3: These reflect actual circulating thyroid hormone activity. Some women have normal TSH but impaired T4-to-T3 conversion, resulting in functionally low T3 (the active form) and hypothyroid symptoms.
Thyroid antibodies (anti-TPO, anti-thyroglobulin): Hashimoto’s thyroiditis is the most common cause of hypothyroidism and is significantly more prevalent in women with PCOS compared to the general population. Detecting antibody positivity identifies autoimmune thyroid disease that may be driving or compounding symptoms.
Prolactin
Hyperprolactinemia can cause menstrual irregularity and anovulation that mimics or co-exists with PCOS. Prolactin should be measured with your PCOS lab tests in the workup of irregular cycles to rule out a pituitary contribution (including prolactinoma).
Lipids and Cardiovascular Markers
Women with PCOS have a significantly elevated risk of dyslipidemia, cardiovascular disease, and non-alcoholic fatty liver disease (NAFLD), newly renamed to MASLD (Metabolic Dysfunction-Associated Steatotic Liver Disease). A full fasting lipid panel should be included in the baseline assessment of PCOS lab tests:
- Total cholesterol
- LDL cholesterol
- HDL cholesterol
- Triglycerides
Elevated triglycerides and low HDL are particularly common in PCOS and are closely associated with insulin resistance. Triglycerides above 1.7 mmol/L and HDL below 1.3 mmol/L in a woman with irregular cycles and androgen excess should raise a strong clinical flag.
Vitamin D
Vitamin D deficiency is prevalent in PCOS, estimated at 67-85% across PCOS populations in studies from Canada and Northern Europe. Vitamin D receptors are present in ovarian tissue and adrenal glands, and deficiency is independently associated with worsened insulin resistance and impaired follicular development.
Measure: 25-OH vitamin D (the storage form). Target: 100-150 nmol/L for PCOS management, not merely the 76 nmol/L threshold used to define sufficiency in general population screening.
Optional But Informative PCOS Lab Tests
CRP (C-reactive protein): Marker of systemic inflammation. Chronically elevated in many women with PCOS; tracks improvement with anti-inflammatory interventions. Inflammation, insulin resistance and elevated total testosterone are intertwined.
Ferritin: Often elevated in insulin resistance (ferritin is an acute-phase reactant and can be falsely elevated by inflammation). Iron deficiency is also common, particularly in women with heavy periods.
Cortisol: In women with significant adrenal androgen contribution (elevated DHEA-S), 24-hour urinary cortisol or a morning salivary cortisol can help characterize the HPA axis contribution to the picture.
What to Do With the PCOS Lab Tests
This is where many patients get lost. A normal result from a doctor who only ran TSH and total testosterone tells you very little. What you’re building is a picture of which mechanisms are driving your PCOS:
- Insulin-driven PCOS: Elevated fasting insulin (>75 pmol/L), high HOMA-IR, elevated LH:FSH, elevated androgens → prioritize insulin sensitization (diet, exercise, inositol, NAC, berberine)
- Adrenal PCOS: Elevated DHEA-S, normal-range LH:FSH ratio → diet, exercise, and adrenal stress management are central; cortisol management, adaptogenic herbs, sleep optimization
- Inflammatory PCOS: Elevated CRP, normal-range insulin, moderate androgen elevation → anti-inflammatory dietary pattern, omega-3s, gut health, anti-inflammatory herbs.
Most women with PCOS have elements of more than one of these patterns. Thorough PCOS lab tests tell you where to find the greatest leverage.
Dr. Pamela Frank is a naturopathic doctor with 26 years of clinical experience and a background in hospital medical laboratory technology. She practices in Toronto, Ontario, and has a special interest and clinical focus on evidence-based hormonal and metabolic health.
References for PCOS Lab Tests
Franks, S. (2004). The Rotterdam ESHRE/ASRM-sponsored PCOS consensus workshop group. Revised 2003 consensus on diagnostic criteria and long-term health risks related to polycystic ovary syndrome (PCOS). https://doi.org/10.1093/HUMREP/DEH098
Teede HJ, Misso ML, Costello MF, Dokras A, Laven J, Moran L, Piltonen T, Norman RJ; International PCOS Network. Recommendations from the international evidence-based guideline for the assessment and management of polycystic ovary syndrome. Fertil Steril. 2018 Aug;110(3):364-379. doi: 10.1016/j.fertnstert.2018.05.004. Epub 2018 Jul 19. PMID: 30033227; PMCID: PMC6939856.
Bozdag G, Mumusoglu S, Zengin D, Karabulut E, Yildiz BO. The prevalence and phenotypic features of polycystic ovary syndrome: a systematic review and meta-analysis. Hum Reprod. 2016 Dec;31(12):2841-2855. doi: 10.1093/humrep/dew218. Epub 2016 Sep 22. PMID: 27664216.
Majid H, Masood Q, Khan AH. Homeostatic Model Assessment for Insulin Resistance (HOMA-IR): A Better Marker for Evaluating Insulin Resistance Than Fasting Insulin in Women with Polycystic Ovarian Syndrome. J Coll Physicians Surg Pak. 2017 Mar;27(3):123-126. PMID: 28406767.
