Hormone Panel for PCOS
For suspected PCOS, order total testosterone (preferably by LC-MS/MS), free testosterone or calculated free testosterone, TSH, and prolactin as your essential first-line hormone tests. 1
Essential First-Line Hormone Tests
Total testosterone is the single best initial biochemical marker, with 74% sensitivity and 86% specificity for PCOS diagnosis. 1, 2 Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is the mandatory preferred assay method, showing superior specificity (92%) compared to direct immunoassays (78%). 1, 2
Free testosterone demonstrates superior sensitivity of 89% with 83% specificity and should be assessed alongside total testosterone. 1, 2 If direct measurement is unavailable, calculate free testosterone using the Vermeulen equation from high-quality total testosterone and SHBG measurements. 3
Measure TSH to rule out thyroid disease as a cause of menstrual irregularity—this is a critical exclusion criterion before confirming PCOS. 1, 2
Measure prolactin using morning resting serum levels to exclude hyperprolactinemia, with levels >20 μg/L considered abnormal. 1, 2 If elevated, confirm with 2-3 samples at 20-60 minute intervals via indwelling cannula to exclude stress-related spurious elevation. 2
Additional Hormonal Tests to Consider
Measure LH and FSH between days 3-6 of menstrual cycle (if cycles occur), calculating based on an average of three estimations taken 20 minutes apart. 1, 2 An LH/FSH ratio >2 suggests PCOS, though this is abnormal in only 35-44% of women with PCOS, making it a poor standalone diagnostic marker. 2, 4
If total testosterone and free testosterone are normal but clinical suspicion remains high, measure androstenedione (A4) with 75% sensitivity and 71% specificity, and DHEAS with 75% sensitivity and 67% specificity. 2 These have poorer specificity than total/free testosterone and should only be used as adjunctive tests. 2
Measure mid-luteal phase progesterone levels to confirm anovulation, with levels <6 nmol/L indicating anovulation. 1, 2
Mandatory Metabolic Screening
All women with PCOS require metabolic screening due to increased risk of type 2 diabetes, dyslipidemia, and cardiovascular disease. 2
- Perform a two-hour oral glucose tolerance test with 75g glucose load to screen for glucose intolerance and type 2 diabetes. 1, 2
- Measure fasting lipid panel including total cholesterol, LDL, HDL, and triglycerides, with target LDL <100 mg/dL, HDL >35 mg/dL, and triglycerides <150 mg/dL. 1, 2
- Calculate BMI (BMI >25 considered overweight) and measure waist-hip ratio (WHR >0.9 indicates truncal obesity and central obesity). 1, 2
- Measure fasting glucose and insulin levels, with glucose/insulin ratio >4 suggesting reduced insulin sensitivity. 1, 2
Critical Caveats and Common Pitfalls
If the patient is on hormonal contraception (including Implanon), hormone testing is unreliable and should be deferred until after removal or expiration of the contraceptive, as progestin suppresses the hypothalamic-pituitary-ovarian axis. 3
Total testosterone is abnormal in only 70% of women with confirmed PCOS, meaning 30% have normal testosterone levels despite having the condition. 2, 4 The presence of clinical hyperandrogenism (hirsutism, acne, or alopecia) plus irregular menstrual cycles can establish PCOS diagnosis even with normal laboratory values. 1, 2
Do not use AMH levels as a diagnostic test due to lack of standardization, no validated cut-offs, and significant overlap between women with and without PCOS, particularly in younger women. 3, 1, 2
Do not rely on LH/FSH ratio as a primary diagnostic criterion—it should be abandoned as a biochemical criterion because of its low sensitivity (abnormal in only 35-44% of PCOS cases). 2, 4
Exclusion of Other Conditions
Screen for Cushing's syndrome if patient has buffalo hump, moon facies, hypertension, abdominal striae, or central fat distribution. 1, 2
Consider androgen-secreting tumors if rapid onset of symptoms, severe hirsutism, or very high testosterone levels (androstenedione >10.0 nmol/L). 1, 2
If DHEAS is elevated, consider non-classical congenital adrenal hyperplasia. 1, 2
Special Considerations for Adolescents
In adolescent females, PCOS diagnosis requires hyperandrogenism (clinical or biochemical) in the presence of persistent oligomenorrhea lasting 2-3 years beyond menarche. 1 Do not use ultrasound for PCOS diagnosis in adolescents with gynecological age <8 years post-menarche due to high false-positive rates from normal multifollicular ovaries. 3, 1