Comparison of bone density decrease and risk of secondary hyperparathyroidism after SADI-S and SG: a single-center retrospective cohort study
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Zixian Guo1, Subo Ma1, Jingxiang Chu1
1Department of General Surgery, China-Japan Union Hospital of Jilin University, Changchun, Jilin, China.
Background:
Single-anastomosis duodeno-ileal bypass with sleeve gastrectomy (SADI-S), a modified biliopancreatic diversion procedure, offers substantial metabolic benefits; however, its short- to mid-term impact on bone health compared with sleeve gastrectomy (SG) remains unclear.
Objectives:
To compare bone mineral density (BMD), the calcium-vitamin D-parathyroid hormone (PTH) axis, and the risk of secondary hyperparathyroidism (SHPT) between SADI-S and SG at 1 and 2 years after surgery.
Setting:
Single-center retrospective cohort study.
Methods:
We retrospectively analyzed patients with metabolic syndrome who underwent SADI-S (n = 112) or SG (n = 197) between October 2018 and October 2024. Body weight, body mass index (BMI), serum calcium, PTH, and 25-hydroxyvitamin D3 were collected preoperatively and at 1 and 2 years postoperatively, together with BMD and T-scores of the femoral neck, total hip, and lumbar spine measured by dual-energy X-ray absorptiometry (DXA). Abnormal bone mass was defined as osteopenia (-2.5 | < | T ≤ -1.0) or osteoporosis (T ≤ -2.5), and SHPT was defined as PTH >68 pg/mL. Between-group comparisons were performed using the independent-samples t test, Mann-Whitney U test, χ2 test, or Fisher exact test, as appropriate.
Results:
Preoperative BMI was higher in the SADI-S group than in the SG group (42.6 ± 6.5 vs. 34.7 ± 5.9 kg/m2, P < .001); despite this difference, preoperative bone metabolic indices were comparable between groups (all P > .05). At 1 year, total-hip BMD (.95 ± .13 vs. 1.04 ± .16 g/cm2, P = .017) and T-score (-.49 ± 1.21 vs. .44 ± 1.44, P = .001) were already significantly lower in the SADI-S group. At 2 years, the between-group differences widened: total-hip BMD (.85 ± .15 vs. 1.00 ± .17 g/cm2, P < .001) and T-score (-1.29 ± 1.48 vs. .22 ± 1.30, P < .001) were significantly lower in the SADI-S group, and the prevalence of abnormal bone mass reached 65.7% (23/35) versus 21.4% (6/28) in the SG group (P < .001). Serum calcium remained persistently lower in the SADI-S group (2-year: 2.33 ± .13 vs. 2.42 ± .08 mmol/L, P < .001), median PTH was higher (77.14 vs. 40.68 pg/mL, P < .001), and the incidence of SHPT was higher (48.8% vs. 13.8%, P = .004). The prevalence of vitamin D deficiency increased in both groups at 1 year and declined during the second year, but remained higher overall in the SADI-S group (1 year: 56.7% vs. 53.6%; 2 years: 51.4% vs. 25.0%).
Conclusions:
Compared with SG, SADI-S is associated with more pronounced and progressively worsening bone loss and a higher risk of SHPT, potentially related to compensatory PTH elevation driven by reduced intestinal calcium absorption. Patients undergoing SADI-S may require closer bone health surveillance and individualized intervention.
