Abstract Disclosure: N. Safwan: None. E.R. Uddenberg: None. M.D. Hurtado: None. M. Saadedine: None. S.S. Faubion: None. O. Obrutu: None. S.L. Berga: None. M.D. Pisarska: None. C. Bairey Merz: None. C.L. Shufelt: None. Background: Functional hypothalamic amenorrhea (FHA) accounts for 30% of secondary amenorrhea due to suppression of GnRH associated hypercortisolemia resulting in chronic hypoestrogenemia. FHA occurs as a result of varying combinations of psychosocial stress, excessive exercise, and/or disordered eating. FHA is associated with decreased bone mineralization; however, it is unknown how bone health compares to older, menopausal women who also experience bone loss. We compared dual-energy x-ray absorptiometry (DXA) bone health parameters among women with FHA, eumenorrheic controls, and recently menopausal women and evaluated if previous oral contraceptive (OC) use among FHA women has an impact on bone mineral density (BMD). Methods: This cross-sectional study included 20 women with FHA, 9 eumenorrheic controls, and 12 recently menopausal women who underwent hip and spine DXA. All participants were not on hormone therapy. FHA was defined as amenorrhea >3 consecutive months, estradiol <50 pg/ml, FSH <10 mIU/L, and LH <10 mIU/L, excluding other etiologies including PCOS, prolactinoma, thyroid dysfunction, and pregnancy. Eumenorrheic controls had self-reported monthly menses confirmed with day 22-24 progesterone >3 ng/ml. Recently menopausal women had natural menopause <3 years of final menstrual period, and FSH >30 mIU/L. DXA bone health parameters were measured using Lunar iDXA (GE) including BMD from the lumbar spine (L1-L4) and hip. Statistical analysis included nonparametric testing with pairwise Wilcoxon rank sum and Kruskal Wallis, reported as median [interquartile ranges]. Results: By design, the mean age of FHA was 28 ± 6 yr, 29 ± 3 yr for controls, and 54 ± 2 yr for recently menopausal women (p<0.0001). There were no differences in weight or BMI among the groups (p=0.27, p=0.30, respectively). BMD L1-L4 differed among the three groups with 1.10 g/cm2 [1.00, 1.24] for FHA, 1.18 [1.15, 1.29] for eumenorrheic controls, and 1.02 [0.96, 1.08] for menopausal women (p=0.002). Pairwise analysis revealed a significant difference in BMD L1-L4 between FHA and controls (p=0.04) and menopausal women and controls (p=0.009, age-adjusted). However, there was no difference in BMD L1-L4 between FHA and menopausal women (p=0.08, age-adjusted). In FHA women with previous OC use, BMD L1-L4 was not different from eumenorrheic controls (p=0.20), while BMD L1-L4 differed from that of recently menopausal women (p=0.004). These differences were not observed at the hip. Conclusion: Compared to eumenorrheic controls, lumbar spine BMD in young women with FHA (mean age 28 yr) was similar to recently menopausal women (mean age 54 yr) emphasizing the profound bone impact of FHA. Previous OC use seems to mitigate FHA bone mineralization changes. Future studies should investigate if bone health differs among women with FHA based on underlying cause and if previous OC use plays a role in maintaining bone health. Presentation: 6/3/2024