Impact of Roux-en-Y gastric bypass versus sleeve gastrectomy on vitamin D metabolism: short-term results from a prospective randomized clinical trial

To assess postoperative outcomes of sleeve gastrectomy (SG) versus Roux-en-Y gastric bypass (RYGB). Short-term results on vitamin D and parathormone (PTH) metabolism are reported. One hundred patients were randomly assigned to RYGB (n = 45) or SG (n = 55). Vitamin D, PTH, and calcium were assessed at inclusion and after 1, 3, 6, and 12 months (M1, M3, M6, and M12). Eighty-eight patients completed 1-year follow-up. Mean postoperative excess weight loss (%EWL) at M1, M3, M6, and M12 was 25.39, 43.47, 63.75, and 80.38 % versus 25.25, 51.32, 64.67, and 82.97 % in RYGB and SG, respectively. Vitamin D values were statistically significantly higher after SG compared to RYGB at M3 (61.57 pmol/L, standard deviation [SD] 14.29 vs. 54.81 SD 7.65; p = 0.01) and M12 (59.83 pmol/L, SD 6.41 vs. 56.15 SD 8.18; p = 0.02). Vitamin D deficiency rate decreased from 84.62 to 35 % at M6 (p = 0.04) and 48 % at M12 (p = 0.01) in the SG group, while there was no significant improvement in the RYGB group. Serum parathyroid hormone (sPTH) level was decreased significantly in the SG group by M3 (44.8 ng/L vs. 28.6; p = 0.03), M6 (44.9 ng/L vs. 25.8; p = 0.017), and M12 (41.4 ng/L vs. 20.5; p = 0.017). Secondary hyperparathyroidism rate was 20.83 and 24 % at M1 (p = 1), 16.67 and 8 % at M3 (p = 0.41), 14.29 and 0 % at M6 (p = 0.08), and 15 and 0 % at M12 (p = 0.23) in the RYGB and SG groups, respectively. Patients after RYGB had a significantly higher postoperative vitamin D deficiency and higher sPTH levels than after SG.