What screening tests are used to diagnose Polycystic Ovary Syndrome (PCOS)?

Diagnostic Tests for Polycystic Ovary Syndrome (PCOS)

Total testosterone (TT) and free testosterone (FT) should be used as first-line laboratory tests to assess biochemical hyperandrogenism in the diagnosis of PCOS, preferably measured using liquid chromatography with tandem mass spectrometry (LC-MS/MS) due to its superior sensitivity and specificity. 1, 2

Essential Laboratory Tests for PCOS Diagnosis

First-Line Tests

• Androgen Assessment:

  • Total testosterone (TT) - sensitivity 74%, specificity 86% 1
  • Free testosterone (FT) - sensitivity 89%, specificity 83% 1
  • Free Androgen Index (FAI) - sensitivity 78%, specificity 85% 1
  • Note: LC-MS/MS method is strongly preferred over immunoassays for accuracy 1, 2

• Rule Out Other Endocrine Disorders:

  • Thyroid-stimulating hormone (TSH) - to exclude thyroid disorders 1, 2
  • Prolactin level - to exclude hyperprolactinemia 1, 2

• Metabolic Assessment:

  • Two-hour oral glucose tolerance test with 75g glucose load - to screen for insulin resistance and diabetes 1, 2
  • Fasting lipid profile (total cholesterol, LDL, HDL, triglycerides) 1, 2

Second-Line Tests (If First-Line Tests Are Normal but Clinical Suspicion Remains High)

• Androstenedione (A4) - sensitivity 75%, specificity 71% 1, 2
• Dehydroepiandrosterone sulfate (DHEAS) - sensitivity 75%, specificity 67% 1, 2

Excluding Other Causes of Androgen Excess

When evaluating a patient for PCOS, it's crucial to rule out other conditions that can present with similar symptoms:

• Non-classic congenital adrenal hyperplasia:

  • 17-hydroxyprogesterone test 1, 3

• Cushing's syndrome (if clinical features present such as buffalo hump, moon facies, abdominal striae):

  • Overnight dexamethasone suppression test or 24-hour urinary free cortisol 1, 3

• Androgen-secreting tumors (if rapid onset of severe hyperandrogenism or virilization):

  • Very high testosterone or DHEAS levels require further investigation 1, 3

Physical Examination Findings to Document

• Hirsutism (excessive hair growth in male-pattern distribution)
• Acne
• Male-pattern hair loss (androgenic alopecia)
• Acanthosis nigricans (velvety, hyperpigmented skin folds indicating insulin resistance)
• Body mass index (BMI) and waist-hip ratio 1
• Clitoromegaly (if present, suggests more severe hyperandrogenism) 1

Ultrasound Findings

• While polycystic ovaries on ultrasound can support the diagnosis, this finding alone is not sufficient for diagnosis, particularly in adolescents less than 8 years post-menarche 2
• Ultrasound should be considered as an adjunct to biochemical and clinical findings

Important Caveats and Pitfalls

1. Laboratory method matters: Direct androgen immunoassays have limited accuracy; results inconsistent with clinical presentation should be rechecked using LC-MS/MS 1, 2

2. Timing of tests: Hormonal tests should ideally be performed in the early follicular phase of the menstrual cycle in women who are menstruating regularly 4

3. Reference ranges: Ethnicity and age may affect normal reference ranges for androgens, requiring careful interpretation 2

4. Diagnostic criteria confusion: Different diagnostic criteria exist (Rotterdam, Androgen Excess Society), but biochemical hyperandrogenism remains a central feature 3

5. Adolescent diagnosis challenges: Diagnosis can be challenging in adolescents as irregular menstrual cycles and acne are common during this period 5

By following this systematic approach to laboratory testing for PCOS, clinicians can make an accurate diagnosis while ruling out other conditions that may require different management approaches.