The role of sclerostin as a key regulator of bone formation remains unknown after Roux-en-Y gastric bypass (RYGB) or laparoscopic sleeve gastrectomy (SG).

The study objectives were evaluation of sclerostin and Dickkopf-1 (DKK-1) serum levels after surgery and correlations with bone turnover markers (P1NP, CTX), parathyroid hormone (iPTH) and areal bone mineral density (BMD), changes at total body, lumbar spine and total hip.

This was a prospective observational single-center two-arm study in premenopausal women with acute adipositas over 24 months.

Participants were 52 premenopausal women (40 ± 8 years, BMI 43.4) after RYGB and 38 premenopausal women (41 ± 7 years, BMI 45.7) after SG.

Prior to surgery and 1, 3, 6, 9, 12, 18, and 24 months after surgery sclerostin, DKK-1, CTX, P1NP levels and BMD were measured.

Sclerostin, CTX and (to a lesser extent) P1NP increased after surgery and remained elevated during the entire study period (P < 0.001). DKK-1 declined during months 3–9 (P < 0.005) and then remained unchanged, serum phosphate continuously increased (P < 0.001), iPTH remained within the upper normal limit. Sclerostin increases were significantly positively correlated with CTX and P1NP increases and negatively correlated with BMD loss. BMD independently declined regardless of RYGB and SG. Elevations of sclerostin, CTX, P1NP, and phosphate, but not DKK-1 and iPTH, were significant discriminating factors for BMD loss (AUC 0.920).

Rapid and sustained increases of sclerostin, CTX, and to a lesser extent, P1NP cause an increase in bone metabolism and result in BMD loss at all skeletal sites.