Mid-term effects of sleeve gastrectomy on calcium metabolism parameters, vitamin D and parathormone (PTH) in morbid obese women.

BACKGROUND: Despite routine supplementation of vitamins and minerals after bariatric surgery, an important number of patients suffer from deficiencies. Little is still known about the novel restrictive procedure, sleeve gastrectomy.
METHODS: A retrospective study of 30 morbidly obese patients undergoing a laparoscopic sleeve gastrectomy, between May 2008 and September 2010, was performed. Baseline albumin, ferritin, iron, zinc, calcium, vitamin D, parathormone (PTH), vitamin B12, and folic acid were obtained before operation and postoperative determinations 1, 3, 6, 9, 12, 18, and 24 months after surgery.
RESULTS: Before surgery, 96.7% of the patients presented vitamin D deficiency, 20% had elevated PTH, 3.3% hypoalbuminemia, and 3.3% folic acid deficiency. One year after surgery, only one patient (3.3%) presented vitamin D deficiency and had elevated PTH. The rest of parameters were within normal range. The second year after surgery, the results remain similar. A significant difference was obtained when comparing preoperative vitamin D values and postoperative determinations 12 months after surgery (increase of 51.9 ng/dl, 95% confidence interval (CI) (41.8-61.3); p < 0.001). A significant difference was determined when comparing preoperative PTH values and postoperative determinations 3 months after surgery (decrease of 16.6 pg/ml, 95% CI (2.6-30.6); p = 0.03). A significant inverse correlation was observed between weight loss and vitamin D increase at the third month after surgery (Pearson correlation coefficient -0.948; p = 0.033).
CONCLUSIONS: Postoperative values of vitamin D show a progressive increase, while PTH ones present a significant reduction, without any impact on serum calcium levels. We have demonstrated an inverse correlation between weight loss and vitamin D increase at the third month after surgery.