Distinguishing Polycystic Ovary Syndrome Phenotype D from Functional Hypothalamic Amenorrhea with Polycystic Ovarian Morphology: Clinical and Hormonal Insights from a Pilot Retrospective Study.

OBJECTIVES: This study was conducted to compare the clinical and hormonal characteristics among women with polycystic ovary syndrome (PCOS) phenotype D, functional hypothalamic amenorrhea (FHA) with polycystic ovarian morphology (PCOM), and FHA without PCOM and investigate potential markers for their distinction. METHODS: This retrospective pilot study included women who were examined for menstrual irregularities at a Korean tertiary hospital during 2018-2025 with following conditions: PCOS-D (n = 66), FHA with PCOM (n = 10), and FHA without PCOM (n = 29). Clinical features and hormonal profiles were analyzed using nonparametric tests, effect size estimation, and logistic regression. RESULTS: BMI, along with LH, FSH, and AMH levels differed significantly across groups. AMH levels exhibited the following gradient: highest in PCOS, intermediate in FHA-PCOM, and lowest in FHA without PCOM. Subgroup analysis indicated that LH and FSH levels alongside LH/FSH ratio distinguished PCOS-D from FHA-PCOM (all P < 0.001, large effect sizes). Logistic regression revealed LH/FSH ratio as the only independent predictor (OR 58.88, 95% CI 3.29-1054.27). FHA without PCOM exhibited more persistent amenorrhea, whereas FHA-PCOM appeared milder and possibly reversible. CONCLUSION: LH/FSH ratio, supported by BMI and clinical history, may help distinguish PCOS-D from FHA-PCOM. FHA-PCOM represents a distinct but understudied subgroup. These results are preliminary and require validation through larger prospective studies.