What is PCOS?
Polycystic Ovary Syndrome is a hormonal disorder characterized by a combination of symptoms including irregular periods, excess androgen levels, and polycystic ovarian morphology. PCOS is diagnosed when at least two of three criteria are present (Rotterdam Criteria):
- Irregular or absent periods - indicating lack of ovulation
- Signs of high androgens - elevated testosterone levels, excess facial or body hair, acne, or hair loss
- Polycystic ovaries on ultrasound - though not all women with PCOS develop visible cysts
Beyond Reproductive Health
PCOS is associated with metabolic concerns including insulin resistance, increased diabetes risk, cardiovascular issues, and inflammation. This makes comprehensive blood testing essential for both diagnosis and ongoing management.
📘 Want to Dive Deeper?
Our PCOS 101 Complete Guide covers everything in this article and more—including the 4 types of PCOS, personalized treatment strategies, fertility information, and practical tracking tools. Learn more about the guide →
Common PCOS Symptoms That Warrant Testing
If you experience multiple symptoms from this list, consider discussing PCOS testing with your healthcare provider:
Reproductive & Hormonal Symptoms
- Irregular menstrual cycles (cycles longer than 35 days or fewer than 8 periods per year)
- Missed or absent periods
- Heavy bleeding when periods do occur
- Difficulty conceiving or infertility
- Excess facial and body hair (hirsutism) - affecting up to 70% of women with PCOS
- Male-pattern hair loss or thinning on the scalp
- Persistent acne, especially on the back, chest, and face
Metabolic Symptoms
- Weight gain or difficulty losing weight, particularly around the abdomen
- Darkened patches of skin (acanthosis nigricans) in body creases
- Skin tags in the armpits or neck area
- Fatigue and low energy levels
Emotional & Mental Health
- Anxiety or depression
- Mood swings
- Negative body image concerns
Essential PCOS Blood Biomarkers: What to Test and Why
A comprehensive PCOS blood panel should assess multiple systems - hormonal, metabolic, and inflammatory markers. Here's a breakdown of the key biomarkers:
💡 Did You Know? There Are 4 Types of PCOS
Not all PCOS is the same. Understanding which of the 4 types you have (Insulin-Resistant, Post-Pill, Inflammatory, or Adrenal) helps you choose the right treatments and supplements. Our comprehensive PCOS 101 Guide includes detailed descriptions of each type with specific biomarker patterns and personalized treatment approaches.
Hormonal Biomarkers
Anti-Müllerian Hormone (AMH) Key Marker
Why it matters: AMH is often significantly elevated in PCOS due to the accumulation of immature follicles in the ovaries. It's one of the most reliable markers for assessing ovarian reserve and PCOS diagnosis.
Typical PCOS finding: Elevated levels above normal range
Clinical significance: High AMH correlates with polycystic ovarian morphology and can indicate reproductive disturbances even when ultrasound findings are unclear.
Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH)
Why it matters: The LH/FSH ratio is a classic PCOS marker. Women with PCOS often have an elevated LH or an increased LH/FSH ratio (typically >2:1).
Typical PCOS finding: Elevated LH with normal or low FSH
Clinical significance: This imbalance disrupts normal ovulation. However, the LH/FSH ratio is abnormal in only 35-44% of PCOS cases, so a normal ratio doesn't rule out PCOS.
Testing timing: Ideally tested during days 2-5 of the menstrual cycle (early follicular phase)
Total Testosterone Most Common
Why it matters: Testosterone is the most frequently abnormal biochemical marker in PCOS, with elevated levels found in approximately 70% of cases.
Typical PCOS finding: Elevated above normal female range
Clinical significance: High testosterone contributes to hirsutism (excess hair growth), acne, and male-pattern baldness. It's the single best hormonal indicator of PCOS.
Free Testosterone and Free Androgen Index (FAI)
Why it matters: Free testosterone represents the biologically active portion of testosterone not bound to proteins. The FAI (calculated as Total Testosterone/SHBG × 100) estimates free testosterone levels.
Typical PCOS finding: Elevated free testosterone or high FAI
Clinical significance: Provides a more accurate assessment of androgen activity than total testosterone alone.
Sex Hormone Binding Globulin (SHBG)
Why it matters: SHBG binds to sex hormones in the blood, making them inactive. Low SHBG means more free (active) testosterone is available.
Typical PCOS finding: Decreased levels, especially in women with insulin resistance or obesity
Clinical significance: Low SHBG is a predictive biomarker for PCOS risk and correlates with metabolic dysfunction.
Androstenedione
Why it matters: A precursor to testosterone and estrogen, androstenedione can be elevated when other androgens appear normal.
Typical PCOS finding: Elevated in approximately 53% of PCOS cases
Clinical significance: Provides additional evidence of hyperandrogenism when testosterone levels are borderline.
Prolactin
Why it matters: Helps rule out hyperprolactinemia, which can cause similar symptoms to PCOS including irregular periods and infertility.
Typical PCOS finding: Usually normal
Clinical significance: Elevated prolactin suggests a different diagnosis requiring alternative treatment.
Progesterone
Why it matters: Low progesterone indicates lack of ovulation (anovulation).
Typical PCOS finding: Low levels, especially mid-luteal phase (day 21 of cycle)
Clinical significance: Confirms whether ovulation is occurring regularly.
Thyroid Function Markers
Thyroid Stimulating Hormone (TSH), Free T3, Free T4
Why it matters: Thyroid disorders can mimic PCOS symptoms including irregular periods, weight gain, and fatigue.
Typical PCOS finding: Usually normal, but thyroid dysfunction can coexist with PCOS
Clinical significance: Essential to rule out thyroid disease as a cause or contributing factor to symptoms.
Metabolic Biomarkers
Fasting Glucose and HbA1c Critical
Why it matters: Many women with PCOS have insulin resistance, increasing their risk for prediabetes and type 2 diabetes.
Typical PCOS finding: May show elevated fasting glucose or HbA1c indicating poor glucose control
Clinical significance: Early detection of glucose dysregulation allows for lifestyle interventions and medication to prevent diabetes. Up to 50% of women with PCOS develop type 2 diabetes by age 40.
Fasting Insulin
Why it matters: Insulin resistance is a core feature of PCOS. Elevated fasting insulin indicates the body needs more insulin to maintain normal blood sugar.
Typical PCOS finding: Elevated levels
Clinical significance: Identifies insulin resistance before glucose levels become abnormal.
Lipid Profile (Cholesterol, LDL, HDL, Triglycerides)
Why it matters: PCOS is associated with dyslipidemia - increased triglycerides, decreased HDL cholesterol, and increased cardiovascular risk.
Typical PCOS finding: High triglycerides, low HDL cholesterol
Clinical significance: Abnormal lipid patterns increase risk for heart disease, which is already elevated in PCOS.
Inflammatory & Other Markers
C-Reactive Protein (CRP)
Why it matters: CRP is a marker of systemic inflammation. Women with PCOS often have chronic low-grade inflammation.
Typical PCOS finding: Elevated CRP levels
Clinical significance: Chronic inflammation contributes to insulin resistance, metabolic syndrome, and cardiovascular risk.
Vitamin D (25-OH Vitamin D)
Why it matters: Vitamin D deficiency is common in PCOS and may worsen insulin resistance and reproductive dysfunction.
Typical PCOS finding: Often low or deficient
Clinical significance: Supplementation may improve metabolic markers and menstrual regularity in deficient women.
When Should You Get Tested for PCOS?
Initial Testing Scenarios
- Irregular periods: If you experience fewer than 8 periods per year or cycles longer than 35 days
- Fertility concerns: Difficulty conceiving after 6-12 months of trying
- Hyperandrogenism signs: Persistent acne, excess facial/body hair, or hair loss
- Metabolic concerns: Unexplained weight gain, difficulty losing weight, or acanthosis nigricans
- Family history: Having a mother or sister with PCOS increases your risk
💡 Optimal Testing Timing
Hormonal markers (LH, FSH, oestradiol): Test during days 2-5 of menstrual cycle
Progesterone: Test on day 21 of a 28-day cycle to assess ovulation
Metabolic markers: Require 8-12 hours of fasting, best done in the morning
Androgens: Test in the morning when levels are highest
Follow-Up Testing Frequency
Once diagnosed with PCOS, regular monitoring helps track treatment effectiveness:
- Every 3-6 months: Glucose and lipid monitoring
- Every 6-12 months: Hormonal panel if undergoing treatment
- Annually: Comprehensive metabolic and cardiovascular risk assessment
Understanding Your PCOS Blood Test Results
⚠️ Important: No Single Test Confirms PCOS
PCOS diagnosis is based on clinical criteria, not a single blood test. Your healthcare provider will consider your symptoms, blood results, physical examination, and ultrasound findings together.
Common PCOS Blood Test Patterns
- Elevated total testosterone or free androgen index
- High LH/FSH ratio (though not always present)
- Elevated AMH
- Low SHBG
- Elevated fasting insulin
- Normal or high-normal glucose
- Low HDL and/or high triglycerides
What If Results Are Borderline or Normal?
Remember that up to 30% of women with PCOS have normal hormonal blood tests. If you have symptoms but normal labs:
- PCOS is still possible - diagnosis can be made based on symptoms and ultrasound alone
- Repeat testing may be needed at optimal times in your cycle
- Discuss other conditions that can mimic PCOS with your doctor
📊 Need Help Interpreting Your Results?
Understanding what your biomarkers mean in the context of PCOS can be challenging. Our PCOS 101 Guide ($19) includes a comprehensive Lab Test Tracker template with reference ranges for all key PCOS markers, plus guidance on what abnormal results mean for each of the 4 PCOS types.
Preparing for Your PCOS Blood Tests
Before Your Test
- Fast for 8-12 hours before metabolic tests (water is allowed)
- Inform your doctor about all medications and supplements
- Schedule hormonal testing for the appropriate day of your cycle
- Book early morning tests when hormone levels peak
- Stay well hydrated to make blood draw easier
- Stop biotin supplements 48 hours before testing
What to Bring
- List of current medications and supplements
- Your menstrual cycle dates for the past few months
- Any previous test results for comparison
- Questions for your healthcare provider