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PCOS · Updated 2026-05-15

The 4 PCOS phenotypes: which one are you?

Written byEditorial Team, HormonalHealth PortalReviewed byEditorial Medical Review, MD, NAMS-CMP· Updated May 15, 2026

Short answer: PCOS has 4 Rotterdam-defined phenotypes (A, B, C, D) based on combinations of androgen excess, ovulatory dysfunction, and polycystic ovaries. Phenotype affects treatment choice.

1 min read

Key takeaways

  • Phenotype A (all 3 criteria) is most insulin-resistant
  • Phenotype D (cysts only, no androgen excess or anovulation) often labeled "lean PCOS"
  • Phenotype determines whether you need metformin/GLP-1, spironolactone, or fertility-focused care

The Rotterdam criteria

Diagnose PCOS if 2 of 3: hyperandrogenism (high T, high free androgen index), oligo/anovulation (irregular cycles), polycystic ovaries on ultrasound (12+ follicles, >2-9mm). Combinations = 4 phenotypes (A/B/C/D).

Why phenotype matters

Phenotype A = highest insulin resistance → metformin / GLP-1 first-line. Phenotype B = anovulatory without cysts → ovulation induction. Phenotype C = ovulatory but androgen-excess → spironolactone. Phenotype D = lean PCOS → focus on cycle regulation.

SC
Reviewed by Editorial Medical ReviewBoard-certified OB/GYN · NAMS-certified · Updated 2026-05-15

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