Laparoscopic sleeve gastrectomy (LSG) has been proven successfully in weight reduction but with potential loss of bone mass. Previous studies indicate that bone morphogenetic protein 4 (BMP4) plays an important role both in bone formation and glucose-lipid metabolism. This study aimed to investigate the alteration of bone mineral density (BMD), bone metabolic parameters and serum BMP4 levels in Chinese obese subjects after LSG. Seventy-one obese patients (34 males, age 31.70±9.61 years and 37 females, age 32.80±11.45 years) were enrolled. BMD (at right hip, femoral neck and lumbar spine 1-4 (L1-L4) by dual-energy X-ray absorptiometry), bone metabolic markers and routine anthropometric/laboratory biochemical parameters at baseline, 3, 6 and 12 months after LSG (abbreviated as 3M/6M/12M Post-LSG) were recorded. Serum BMP4 levels were measured by enzyme-link immunosorbent assay. In females, BMD was significantly decreased at right hip at 3M/6M/12M Post-LSG, femoral neck at 6M/12M Post-LSG and L1-L4 at 6M Post-LSG (all P<0.05). In males, BMD was not significantly changed (all P>0.05). Intriguingly, serum BMP4 levels were reduced slightly at 3M Post-LSG (P=0.463), and significantly at 6M Post-LSG (from 75.51±16.54pg/ml to 65.40±10.51pg/ml, P=0.048) in females, while unchanged in males (all P>0.05). In all subjects, free calcium but not total calcium was increased at 12M Post-LSG (P=0.028). Vitamin D and 25(OH)VD were increased in males at 12M Post-LSG (all P<0.05). Osteocalcin was increased in males at 3M/6M/12M Post-LSG and in females at 3M/6M Post-LSG (all P<0.05). Type I collagen was increased in males at 3M/6M Post-LSG and in females at 3M/6M/12M Post-LSG (all P<0.05).
In conclusion, the change of BMD differs between genders after LSG, significantly decreased in females while unchanged in males. Moreover, the decreased BMP4 levels may partly account for the diminished BMD in Chinese female obese subjects after LSG.
X. Wang: None. L. Li: None. C. Zhu: None. J. Gao: None. S. Qu: None.