The Impact of Laparoscopic Sleeve Gastrectomy on Plasma Ghrelin Levels: a Systematic Review

Within the last decade, several authors have proposed laparoscopic sleeve gastrectomy (LSG) as a potential definitive treatment for morbid obesity. While initially perceived as being a solely restrictive procedure, it is now theorized to have additional hormonal effects (primarily the reduction of circulating levels of plasma ghrelin). However, there is limited supporting evidence for this claim. Therefore, the purpose of our study is to conduct a systematic review of the literature to clarify the effects of LSG on modulation of postoperative ghrelin concentrations. A comprehensive literature search for published or unpublished studies of sleeve gastrectomy (SG) and ghrelin written in English prior to February 2013 was performed using Pubmed, EMBASE, the Cochrane database, and Scopus. Gray literature was also searched through Google. Inclusion criteria for searches were: randomized controlled trials, non-randomized clinical trials, retrospective and prospective cohort studies, or case series. Seven studies were deemed suitable for analysis. The mean patient age was 43 +/- 8.8 years and female percentage was 74.4 +/- 15.3 %. The mean initial BMI was 46.2 +/- 7.8 and mean follow-up time was 9.5 +/- 15 months. The mean postoperative BMI was 37.3 +/- 5.8 over the same follow-up period. Pooled mean preoperative ghrelin levels were 698.4 +/- 312.4 pg/ml and postoperative levels were 414.1 +/- 226.3 pg/ml (P < 0.0001). Pooled analysis of ghrelin levels at 3, 6, and 12 months showed a significant reduction in circulating levels. Our systematic review shows that LSG has a significant effect on ghrelin levels, leading to considerable reduction in circulation levels following surgery. Further research and standardization is necessary to clearly establish a causative relationship between LSG and reduction of circulating ghrelin levels.