MON-792 - Volumetric Bone Density after Metabolic and Bariatric Surgery during Adolescence: Teen-LABS Cohort 15-Years Later

Purpose: Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) are associated with declines in volumetric bone mineral density (vBMD) and microarchitecture, and higher fracture risk in adults. Little is known about the long-term skeletal effects of these metabolic and bariatric surgery (MBS) procedures during adolescence, a critical period for bone acquisition. We have previously demonstrated lower spine BMD in young women who had MBS during adolescence compared to matched, nonsurgical controls. We now aimed to evaluate peripheral vBMD and microarchitecture in female adults who received MBS during adolescence.

Methods: We evaluated a subset of the Teen-LABS cohort, a multicenter, longitudinal study that followed adolescents before and after MBS. We conducted a cross-sectional study comparing high resolution peripheral computed tomography (HRpQCT) derived vBMD and microarchitecture between female participants who had either RYGB or VSG during adolescence (with at least 8 yrs of post-surgical follow-up) and nonsurgical controls matched for sex, age (within 5 yrs), current body mass index (BMI) (within 5 kg/m2), race, and ethnicity. HRpQCT scans were performed using XCT1 for historical controls and XCT2 for surgical participants, with XCT2 images reconstructed to XCT1 to allow comparisons of vBMD, geometry, cortical parameters, and estimated failure load.

Results: Among 19 female participants with history of MBS (14 RYGB and 5 VSG, mean 13.4 +/- 2.6 yrs since surgery) and 24 matched, nonsurgical controls, mean age was 29.5 +/- 5.3 yrs, and mean BMI 38.9 +/- 10.1 kg/m2. Participants who underwent MBS during adolescence had 16.6% lower total vBMD and 31.0% lower trabecular vBMD of the radius, with similar patterns in the tibia, compared to controls (p≤0.002 for all). Further, MBS participants had 8.2% higher cortical vBMD, 11.1% larger total area, and 14.7% larger trabecular area in the radius compared to controls; these changes were also observed in the tibia (p≤0.04 for all). There were no statistically, significant differences in cortical area, cortical thickness, or estimated failure load between the groups. Among surgical participants, C-terminal telopeptide levels were negatively correlated with radial cortical vBMD (r= -0.50, p=0.03) and tibial trabecular vBMD (r= -0.53, p=0.02).

Conclusion: Young adult women who received MBS during adolescence had lower total and trabecular vBMD at both the radius and tibia compared to matched controls. In contrast to studies of older adults, MBS participants had higher cortical vBMD and larger bone size, which offset lower trabecular vBMD, with no net difference in failure load compared to nonsurgical controls. If confirmed with larger studies, these data suggest that long-term skeletal integrity at peripheral sites may be relatively preserved when MBS is performed during adolescence.

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