Secondary Hyperparathyroidism, Bone Density, and Bone Turnover After Bariatric Surgery: Differences Between Roux-en-Y Gastric Bypass and Sleeve Gastrectomy

Abstract

Purpose: Bariatric surgery may lead to metabolic bone disease.

Materials and methods: In this cross-sectional study, we compared the prevalence of secondary hyperparathyroidism (SHPT), impact on bone mass and turnover markers, and serum leptin after Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) in 117 patients (91% female, 51% RYGB, age 41.8 ± 6.7 years, time of surgery 4.3 ± 3.4 years) at different times (1-2 years, > 2 and < 5 years and ≥ 5 years). Body composition, bone mineral density (BMD), by dual-energy X-ray absorptiometry, and bone parameters (PTH, serum calcium, 25OHD, alkaline phosphatase (AP), C-telopeptide (CTX)) were analyzed.

Results: Prevalence of SHPT (PTH ≥ 65 pg/ml) was 26%, RYGB > SG (18.4% vs. 7.8%, p = 0.039), despite similar 25OHD and calcium levels. Mean PTH, CTX, and AP were higher in RYGB vs. SG (61.3 ± 29.5 vs 49.5 ± 32.3 pg/ml, p = 0.001; 0.596 ± 0.24 vs. 0.463 ± 0.23 ng/ml; 123.9 ± 60.8 vs. 100.7 ± 62.0 U/l). There were 13.5% decreases in femoral neck BMD in all patients, over the study period. In the last group, the RYGB group showed greater bone loss in total body BMD (1.016 vs. 1.151 g/cm², - 8.1%, p = 0.003) and total femur BMD (1.164 vs. 1.267 g/cm², - 11.7%, p = 0.007). Mean leptin was lower in the RYGB vs. SG group, with no correlation with BMD in any site.

Conclusion: Our data suggest a more deleterious role of RYGB on bone remodeling up to 5 years postoperatively in comparison with SG.

Keywords: Bariatric surgery; Bone mineral density; Roux-en-Y gastric bypass; Secondary hyperparathyroidism; Sleeve gastrectomy.