## Endocrine Profile in PCOD **Key Point:** The hallmark endocrine abnormality in PCOD is an elevated LH:FSH ratio, typically 3:1 or higher (normal is 1:1). ### Mechanism of LH Elevation 1. **Insulin resistance** → hyperinsulinemia → increased GnRH pulse frequency 2. **Increased GnRH pulsatility** → preferential stimulation of LH-secreting cells 3. **Result:** LH rises disproportionately while FSH remains normal or low ### Why LH:FSH Ratio Matters | Parameter | Normal | PCOD | |-----------|--------|------| | LH (mIU/mL) | 5–25 | 15–50+ | | FSH (mIU/mL) | 5–20 | 5–15 | | LH:FSH ratio | ~1:1 | 3:1 or >3:1 | | Testosterone | Low normal | Elevated | | Androstenedione | Normal | Elevated | **High-Yield:** The elevated LH drives excessive androgen production from theca cells, explaining hirsutism and acne. FSH remains low because negative feedback from estrogen (produced from peripheral aromatization of androgens) suppresses it. **Clinical Pearl:** A normal LH:FSH ratio does NOT exclude PCOD—diagnosis is clinical + ultrasound + metabolic features. However, when present, an elevated ratio is highly suggestive. ### Other Hormonal Features - **Hyperinsulinemia** (fasting insulin often >12 mIU/L) - **Elevated free testosterone** (not total testosterone, which may be only mildly elevated) - **Normal or low SHBG** (due to hyperinsulinemia) - **Elevated AMH** (anti-Müllerian hormone) — reflects increased number of small follicles [cite:Harrison 21e Ch 405]
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