How is hormone level evaluation helpful in Polycystic Ovary Syndrome (PCOS) workup?

Hormone Level Evaluation in PCOS Workup

Serum hormone levels, particularly total testosterone and free testosterone, are essential for diagnosing biochemical hyperandrogenism in PCOS, but Anti-Müllerian Hormone (AMH) should not yet be used as a single diagnostic test. 1

Primary Hormone Panel for PCOS Diagnosis

Androgens (First-Line Tests)

• Total testosterone (TT) is the single best biochemical marker for PCOS, with 70% sensitivity in women with clinical and ultrasound features of PCOS, and demonstrates high specificity (86%) and good sensitivity (74%) for biochemical hyperandrogenism 2, 3
• Free testosterone (FT) should be assessed by equilibrium dialysis or ammonium sulfate precipitation, or calculated using Free Androgen Index (FAI) rather than direct immunoassay, which is highly inaccurate due to low serum concentrations 1, 2
• Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is the preferred laboratory method for androgen measurement due to superior accuracy compared to immunoassays 1, 2
• Androstenedione (A4) can be considered as a secondary test if TT or FT are not elevated, with 53-75% sensitivity but lower specificity (71%) 2, 3
• DHEAS is useful to identify adrenal androgen sources but has limited diagnostic value with lower specificity (67%) and shows no significant difference between PCOS and control groups in many studies 2, 3

Gonadotropins

• LH and FSH should be measured to assess ovulatory dysfunction, though the LH/FSH ratio has poor sensitivity (35-44%) and should not be used as a primary diagnostic criterion 2, 3
• Sex hormone-binding globulin (SHBG) is important for calculating FAI and evaluating bioavailable testosterone, particularly as SHBG levels are affected by age, weight, and medications 1, 2

Anti-Müllerian Hormone (AMH) - Current Status

Guideline Recommendations

• Serum AMH levels should NOT yet be used as an alternative for detecting polycystic ovary morphology (PCOM) or as a single test for PCOS diagnosis 1, 2
• AMH demonstrates significant heterogeneity in diagnostic accuracy with AUC values ranging from 0.67 to 0.92 across studies, and thresholds varying widely from 20 to 55.86 pmol/L 1
• AMH has particular limitations in adolescents where levels overlap considerably with those without PCOS features, making differentiation difficult 1

Future Potential

• Emerging evidence suggests AMH may become useful with improved standardization of assays and established age-specific and ethnicity-specific cut-off values based on large-scale validation 1
• Higher AMH concentrations (>8 ng/mL) predict reduced ovulation rates with clomiphene and metformin treatment (odds ratio 0.23), though ovulation can still occur at very high levels 4

Additional Metabolic and Screening Tests

• TSH should be measured to exclude thyroid disease as part of the differential diagnosis 2
• Prolactin should be measured to rule out hyperprolactinemia, which can mimic PCOS features 2
• Two-hour oral glucose tolerance test should be performed to screen for diabetes risk, given the high prevalence of metabolic dysfunction in PCOS 2
• Fasting lipid profile should be assessed to evaluate cardiovascular risk factors 2
• 17-hydroxyprogesterone testing should be considered if non-classic congenital adrenal hyperplasia is suspected 2

Diagnostic Algorithm

When both irregular menstrual cycles and hyperandrogenism are present clinically, ovarian ultrasound is not necessary for PCOS diagnosis, though it will identify the complete phenotype 1

Recommended Testing Sequence:

1. Measure total testosterone by LC-MS/MS as first-line test - abnormal in 70% of PCOS cases 2, 3
2. If TT is normal, calculate free testosterone using FAI (requires TT and SHBG measurement) 1, 2
3. If both TT and FT are normal, consider A4 and DHEAS to capture additional cases 2
4. Testosterone, androstenedione, or LH (alone or in combination) are elevated in 86% of PCOS cases 3

Critical Pitfalls to Avoid

• Never use direct immunoassay methods for free testosterone measurement - they are highly inaccurate at low serum concentrations 1, 2
• Do not rely on LH/FSH ratio as a diagnostic criterion - it has only 35-44% sensitivity despite being significantly elevated in PCOS 3
• Testosterone levels must be interpreted in context of SHBG, which shows negative correlation with body mass index in PCOS and affects bioavailable testosterone 3
• Normal ranges must be precisely defined for each laboratory's assay using regularly ovulating women in the early follicular phase 3
• Diagnostic accuracy varies by criteria used: Rotterdam criteria show higher sensitivity (77%) but lower specificity (83%) compared to NIH criteria (sensitivity 51%, specificity 94%) 2

Timing and Sample Handling

• Hormone measurements should be obtained in the early follicular phase (days 3-5) in women with some menstrual cyclicity 3, 5
• In amenorrheic women, testing can be performed at any time after excluding pregnancy 5