883d337e-1389-4ccf-bb9f-d8d1354976ce.jpeg
Explain this
Reading File
analyse_media
This is a page from First Aid for the USMLE Step 1 covering two gynecological/endocrine disorders. Here is a full breakdown:
Polycystic Ovary Syndrome (PCOS)
Pathophysiology
PCOS results from dysregulation of ovarian steroidogenesis. The key hormonal derangements are:
- Elevated LH:FSH ratio - LH is disproportionately high compared to FSH
- Excess androgens (testosterone) - produced by theca interna cells stimulated by the high LH
- Reduced follicular maturation - the androgen excess prevents follicles from maturing and rupturing, so they accumulate as cysts
- Anovulation - no ovulation occurs, so no progesterone is produced after the cycle
The ultrasound image in the bottom-left shows the classic "string of pearls" appearance: multiple small follicular cysts arranged along the ovarian periphery.
Diagnosis (Rotterdam Criteria - need 2 of 3)
- Cystic/enlarged ovaries on ultrasound
- Oligo- or anovulation (irregular/absent periods)
- Hyperandrogenism - hirsutism, acne, elevated androgens
Associated Features
- Obesity and insulin resistance (insulin stimulates more androgen production from theca cells)
- Acanthosis nigricans - velvety dark skin patches from insulin resistance
- Increased endometrial cancer risk - because chronic anovulation means unopposed estrogen (no progesterone to balance it), stimulating endometrial proliferation
Treatment
| Goal | Intervention |
|---|---|
| Cycle regulation / endometrial protection | OCPs (oral contraceptive pills) |
| Weight/metabolic improvement | Weight loss (reduces peripheral estrone conversion) |
| Fertility (ovulation induction) | Clomiphene, letrozole |
| Hirsutism / anti-androgen | Spironolactone, finasteride, flutamide |
Primary Ovarian Insufficiency (POI)
Also called premature ovarian failure.
What it is
Premature atresia (depletion) of ovarian follicles in women of reproductive age - specifically before age 40. The ovaries "run out" of follicles too early.
Causes
- Idiopathic - most common
- Chromosomal: Turner syndrome (45,XO), Fragile X premutation
- Autoimmune destruction of ovarian tissue
Because of the genetic associations, karyotype screening is recommended in all patients.
Hormone Pattern
| Hormone | Level | Why |
|---|---|---|
| Estrogen | Low (↓) | Ovaries no longer functional |
| LH | High (↑) | Loss of negative feedback from estrogen |
| FSH | High (↑) | Loss of negative feedback from estrogen/inhibin |
This is the opposite of PCOS, where LH is high but FSH is relatively lower.
Clinical Presentation
Symptoms of menopause occurring after puberty but before age 40: hot flashes, vaginal dryness, amenorrhea, infertility.
Quick Comparison: PCOS vs. POI
| Feature | PCOS | POI |
|---|---|---|
| FSH | Low/normal | High |
| LH | High | High |
| LH:FSH ratio | Elevated | Both equally elevated |
| Estrogen | Normal/high | Low |
| Ovaries | Many cysts | Atrophic, no follicles |
| Fertility | Reduced (treatable) | Severely reduced |
| Cause | Dysregulation | Depletion |
The page also mentions Hyperprolactinemia as another cause of female infertility/anovulation (covered elsewhere on the page), since elevated prolactin suppresses GnRH, reducing LH and FSH.
This is a shared conversation. Sign in to Orris to start your own chat.