Haematological indices and haematinic levels after mini gastric bypass: a matched comparison with Roux-en-Y gastric bypass

Summary Many surgeons believe mini gastric bypass (MGB) is more likely to cause micronutrient malabsorption compared to Roux-en-Y gastric bypass (RYGB). Till date, there is no published study evaluating haematological indices and haematinic levels in patients undergoing MGB and comparing these with a matched cohort of RYGB. Two hundred patients who underwent MGB between October 2012 and October 2015 were matched to 200 patients who underwent RYGB for age, sex, body mass index and time of surgery. We then compared haemoglobin, mean corpuscular volume, iron, ferritin, vitamin B12 and folic acid levels preoperatively and at 6 monthly intervals after surgery until 2 years. The percentage total weight loss was significantly higher in the MGB group compared to the RYGB group at all time points. At 2 years, MGB and RYGB both led to an increase in anaemia rates but the difference was only significant for MGB group. Compared to RYGB, MGB patients were more likely to be anaemic at 2 years, although the difference was not significant statistically (16.6% vs. 12.7%; P value = 0.55). There was a trend for lower iron and folate levels in MGB group compared to RYGB group but the difference was statistically significant at some of the time periods only (significantly lower folate at 6 and 12 months and lower iron at 6 months in the MGB group). MGB leads to a significant increase in anaemia rates in a supplemented cohort. There is a trend towards lower iron and folate levels and higher anaemia rates in MGB group in comparison with RYGB. Larger studies with longer follow-up should evaluate results of MGB with a shorter biliopancreatic limb.