There are conflicting results on bone health after laparoscopic adjustable gastric band (LAGB) and vertical sleeve gastrectomy (VSG). Based on the timing of peak bone mass accrual, we hypothesize that there may be significant and early effects on adolescent bone health after bariatric surgery.
Retrospective, observational study at the Center for Adolescent Bariatric Surgery of 185 adolescents who underwent LAGB (n=98) or VSG (n=87) between 2006 and 2018. Anthropomorphic measurements and fasting morning bone health labs (calcium, 25 and 1,25-vitamin D, and parathyroid hormone (PTH)) were collected at baseline and 6 and/or 12 months after LAGB or VSG. Additional analysis of bone turnover markers (BTMs) was performed in the VSG group. Subjects ≤13 years old and/or with HbA1c ≥7.0% were excluded.
Prior to surgery, the average age was 16.9 years (range 14-19) and the median body mass index was 46.7 kg/m2 (range 36-101). Median percent excess weight loss (EWL) after 6 and 12 months was 15% and 22% after LAGB and 47% and 61% after VSG. Overall, 25-hydroxyvitamin D status improved, and there were no clinical changes in 1,25-dihydroxyvitamin D, parathyroid hormone (PTH), or calcium values. Of note, the VSG group, had a significantly higher rate of vitamin D supplementation (<0.001). BTM analysis in the VSG group showed an increase in collagen type 1 cross-linked c-telopeptide (CTX) from baseline after 6 and 12 months (p<0.001), but osteocalcin only increased in females (p<0.001).
VSG results in significantly more weight change than LAGB, without a differential effect on bone health labs. There were marked increases in BTMs at 6 and 12 months after VSG, which could not be attributed to vitamin D deficiency, hypocalcemia, or hyperparathyroidism. More studies are needed to evaluate the effects of bariatric surgery on adolescent bone health and to correlate the early changes in BTMs with bone mineral density and bone microarchitecture in this patient population.