Effect of different bariatric surgery type on the leukocyte formula

Obesity is associated with higher leukocyte counts, whereas weight loss decreases these counts. It is unknown if different bariatric surgery (BS) types have different effects on leukocytes.

The aim of the study was to determine predictors of leukocyte and their subset count variation in patients submitted to BS.

Tertiary care university hospital, Porto, Portugal.

This was a retrospective analysis of patients submitted to Roux-en-Y gastric bypass (RYGB), laparoscopic adjustable gastric banding (LAGB), or sleeve gastrectomy (SG). Leukocyte and subset counts were compared between baseline and 1-year postsurgery and between BS types. A multivariate linear regression model was built to study determinants of leukocyte and subset variation.

We analyzed 764 patients: 238 submitted to LAGB; 452 to RYGB, and 74 to SG. Mean age was 42 years and 86.6% were women. All BS types were associated with a decrease in leukocyte and neutrophil counts but the variation in body mass index and homeostatic model assessment (HOMA-IR) were the only variables independently associated with a decrease 1-year postsurgery. Monocytes increased in patients submitted to LAGB and decreased in those who underwent RYGB and SG. The BS type was independently associated with monocyte variation. Patients who underwent RYGB and SG had a decrease in monocyte counts of 77/µL and 62/µL, respectively, compared with LAGB.

Weight and insulin resistance are the main predictors of leukocyte and neutrophil variation after BS. The specific type of BS is a determinant of monocyte count variation independent of the amount of weight loss or the degree of insulin resistance improvement.