How do you screen for Polycystic Ovary Syndrome (PCOS)?

Screening for Polycystic Ovary Syndrome (PCOS)

The diagnosis of PCOS requires the presence of at least two of the three Rotterdam criteria: chronic anovulation, hyperandrogenism (clinical or biochemical), and polycystic ovarian morphology on ultrasound, with exclusion of other disorders. 1

Diagnostic Approach

First-Line Laboratory Tests

• Total testosterone - most frequently abnormal biochemical marker (70% sensitivity) 2
• Free testosterone - more sensitive than total testosterone, ideally determined through equilibrium dialysis techniques 1, 3
• Thyroid-stimulating hormone (TSH) - to exclude thyroid disorders 1
• Prolactin - to exclude hyperprolactinemia 1
• 17-hydroxyprogesterone - to exclude congenital adrenal hyperplasia 1

Additional Recommended Tests

• Luteinizing hormone (LH) and Follicle-stimulating hormone (FSH) - elevated LH/FSH ratio is common but has low sensitivity (only 35-44% of PCOS patients) 2
• Androstenedione - elevated in 53% of PCOS patients 2
• Sex hormone-binding globulin (SHBG) - often decreased in PCOS 1

Clinical Assessment

1. Menstrual history:

   • Cycle length >35 days suggests chronic anovulation
   • Oligomenorrhea (fewer than 8 menstrual cycles per year)
   • Persistent oligomenorrhea 2-3 years beyond menarche is particularly significant 3

2. Clinical hyperandrogenism assessment:

   • Hirsutism - gradual onset that intensifies with weight gain 3
   • Acne - severe or resistant to conventional treatments 3
   • Hair loss - typically at vertex, crown, or diffuse pattern 3

Imaging

• Transvaginal ultrasound (preferred for adult women)
• Transabdominal or transrectal ultrasound (for adolescents) 1
• Key measurements:
  • Follicle number per whole ovary (FNPO) ≥25 small follicles (2-9 mm) 1, 3
  • Ovarian volume (OV) >10 mL 1, 3

Special Populations

Adolescents

• Diagnosis is particularly challenging due to overlap with normal pubertal changes 3
• Focus on:
  • Persistent oligomenorrhea 2-3 years post-menarche
  • Clinical hyperandrogenism
  • Biochemical evidence of oligo/anovulation
• Ultrasound is not recommended as first-line in females <17 years due to common finding of multicystic ovaries 3

Self-Screening Tools

• Self-reported hirsutism using modified Ferriman-Gallwey score ≥3 from upper lip and abdomen has 76% sensitivity and 70% specificity 4
• Self-reported use of any depilatory practices has 71% sensitivity and 74% specificity 4
• Combined, these measures provide 93% sensitivity with 52% specificity 4

Exclusion of Other Disorders

• Additional tests to exclude other disorders may include:
  • Overnight dexamethasone suppression test
  • 24-hour urinary free cortisol
  • Fasting lipid profile 1

Metabolic Screening

• Fasting glucose/insulin ratio
• 2-hour 75g oral glucose tolerance test (OGTT) - recommended for patients with BMI >25 kg/m² 1
• Fasting lipid profile - to assess cardiovascular risk 1

Common Pitfalls and Caveats

1. Relying solely on LH/FSH ratio - has low sensitivity and should not be used as the primary diagnostic criterion 2
2. Hormonal contraceptive use - can mask symptoms and affect laboratory results 4
3. Failure to exclude other disorders - such as thyroid dysfunction, hyperprolactinemia, and congenital adrenal hyperplasia 1, 5
4. Overreliance on ultrasound in adolescents - multicystic ovaries are common in this age group 3
5. Not considering the limitations of testosterone assays - especially in ranges applicable to young girls 3

By following this structured approach to screening for PCOS, clinicians can improve early identification and diagnosis of this common endocrinopathy, leading to appropriate interventions that can reduce long-term health risks.