Characteristics of menstrual irregularities across eating disorder subtypes in postmenarcheal adolescents.

UNLABELLED: This study aimed to characterize menstrual irregularities in adolescents with eating disorder (ED) and assess their variation across diagnostic subtypes, clinical course, and clinical determinants. This retrospective study included postmenarcheal female adolescents with EDs and followed in an adolescent medicine clinic between 2015 and 2025. Demographic, anthropometric, clinical, and menstrual data at admission and during follow-up were extracted from medical records. The study included 491 adolescents: 178 (36.3%) with anorexia nervosa (AN), 184 (37.5%) with atypical AN (AAN), 76 (15.5%) with bulimia nervosa (BN), 18 (3.7%) with avoidant/restrictive food intake disorder, and 35 (7.1%) with unspecified feeding or eating disorder. Menstrual irregularities were most prevalent in AN, followed by AAN and BN (p < 0.001). Secondary amenorrhea predominated in AN (p < 0.001), whereas oligomenorrhea was more common in AAN and BN (p = 0.004). Compared to AAN, adolescents with AN had longer duration of amenorrhea and required greater weight gain for menstrual recovery (all p < 0.05). All patients with ≥ 1-year follow-up achieved menstrual recovery. In logistic regression analysis, AN diagnosis (vs. AAN), restrictive subtype (vs. binge-purge subtype), excessive exercise, hospitalization at presentation, greater weight loss, and longer weight loss duration were associated with higher odds of amenorrhea, whereas higher percentage of mean body mass index and higher minimum weight were protective (all p < 0.001). Excessive exercise and longer weight loss duration were associated with higher odds of oligomenorrhea (both p < 0.05). CONCLUSION: Menstrual irregularities occur across all ED subtypes, but amenorrhea is most common in restrictive disorders, particularly AN. As menstrual irregularities are associated with greater weight loss and markers of illness severity, early recognition and treatment of EDs may help optimize menstrual outcomes. WHAT IS KNOWN: • Menstrual irregularities are common in adolescents with eating disorders, particularly anorexia nervosa, and are associated with hypothalamic-pituitary-ovarian axis dysfunction. • Comparative data on menstrual irregularities across eating disorder subtypes in adolescents remain limited. WHAT IS NEW: • Menstrual irregularities were among the most common presenting complaints in adolescents with anorexia nervosa, atypical anorexia nervosa, and bulimia nervosa. • Amenorrhea and oligomenorrhea had distinct clinical determinants across eating disorder subtypes. • Adolescents with anorexia nervosa required greater weight restoration for menstrual recovery than those with atypical anorexia nervosa.