## PCOD vs. Functional Hypothalamic Amenorrhoea (FHA) **Key Point:** Both PCOD and FHA present with secondary amenorrhoea and anovulation, but they differ fundamentally in hormone profile and ovarian structure. PCOD is a hyperandrogenic, polycystic ovarian disorder; FHA is a hypogonadotropic, hypogonadal state due to stress, weight loss, or excessive exercise. ### Comparison Table | Feature | PCOD | Functional Hypothalamic Amenorrhoea (FHA) | | --- | --- | --- | | **Androgen levels** | Elevated (free T, androstenedione) | Normal or low | | **LH/FSH ratio** | Elevated (3:1 or higher) | Low (suppressed GnRH) | | **Ovarian morphology** | Polycystic (>12 follicles per ovary) | Normal ovaries | | **BMI** | Normal or elevated | Low (often <19) | | **Trigger** | Genetic, metabolic | Stress, weight loss, overexercise | | **Estradiol** | Normal or elevated | Low | | **Prolactin** | Normal | Normal (unless stress-related) | | **Reversibility** | Chronic, requires treatment | Reversible with weight gain/stress reduction | **High-Yield:** The combination of **elevated androgens + polycystic ovarian morphology** is pathognomonic for PCOD. In FHA, androgens are normal and ovaries are structurally normal; amenorrhoea results from suppressed GnRH due to energy deficit or stress. **Clinical Pearl:** A woman with FHA typically has a history of weight loss, intense exercise, or psychological stress. Her ovaries are normal on ultrasound, and her amenorrhoea resolves with weight restoration or stress reduction. PCOD persists regardless of lifestyle changes. **Mnemonic:** PCOD = **Poly**cystic ovaries + **Hyper**androgenism; FHA = **Normal** ovaries + **Hypo**gonadotropism. **Warning:** Do not confuse elevated prolactin (which can suppress GnRH and cause amenorrhoea) with PCOD. Prolactin is normal in both PCOD and uncomplicated FHA. Elevated prolactin suggests a separate diagnosis (prolactinoma, hypothyroidism).
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