Incidence and risk factors for the development of anemia following gastric bypass surgery

AIM:To evaluate the incidence and risk factors for the development of anemia after RouxenY gastric bypass (RYGB).METHODS: A retrospective analysis of patients undergoing RYGB from January 2003 to November 2007 was performed. All patients had a preoperative body mass index > 40 kg/m2. A total of 206 patients were evaluated. All patients were given daily supplements of ferrous sulfate tablets for 2 wk following their operation. Hematological and metabolic indices were routinely evaluated following surgery. Patients were followed for a minimum of 86 wk.RESULTS: There were 41 males and 165 females with an average age of 40.8 years. 21 patients (10.2%) developed postoperative anemia and 185 patients (89.8%) did not. Anemia was due to iron deficiency in all cases. The groups had similar demographics, surgical procedure and comorbidities. Menstruation (P = 0.02) and peptic ulcer disease (P = 0.01) were risk factors for the development of postoperative anemia.CONCLUSION: Iron deficiency anemia is frequent. RYGB surgery compounds occult blood loss. Increased ferrous sulfate supplementation may prevent iron depletion in populations at increased risk.

Two case reports of acute upper gastrointestinal bleeding from duodenal ulcers after Roux-en-Y gastric bypass surgery: Endoscopic diagnosis and therapy by single balloon or push enteroscopy after missed diagnosis by standard esophagogastroduodenoscopy

The diagnosis and opportunity for endoscopic therapy of gastric or duodenal lesions may be missed at esophagogastroduodenoscopy(EGD) because of technical difficulty in intubating at EGD the postoperatively excluded stomach and proximal duodenum in patients status post Roux-en-Y gastric bypass(RYGB). Two cases are reported of acute upper gastrointestinal bleeding 10 or 11 years status postRYGB, performed for morbid obesity, in which the EGD was non-diagnostic due to failure to intubate the excluded stomach and proximal duodenum, whereas subsequent push enteroscopy or single balloon enteroscopy were diagnostic and revealed 4-cm-wide or 5-mm-wide bulbar ulcers and even permitted application of endoscopic therapy. These case reports suggest consideration of push enteroscopy, or single balloon enteroscopy, where available, in the endoscopic evaluation of acute UGI bleeding in patients status post RYGB surgery when the EGD was non-diagnostic because of failure to intubate these excluded segments.

Potential contribution of the gut microbiota to hypoglycemia after gastric bypass surgery

Obesity has become a global health problem. Lifestyle modification and medical treatment only appear to yield short-term weight loss. Roux-en-Y gastric bypass (RYGB) is the most popular bariatric procedure, and it sustains weight reduction and results in the remission of obesity-associated comorbidities for obese individuals. However, patients who undergo this surgery may develop hypoglycemia. To date, the diagnosis is challenging and the prevalence of post-RYGB hypoglycemia (PRH) is unclear. RYGB alters the anatomy of the upper gastrointestinal tract and has a combined effect of caloric intake restriction and nutrient malabsorption. Nevertheless, the physiologic changes after RYGB are complex. Although hyperinsulinemia, incretin effects, dysfunction of β-cells and α-cells, and some other factors have been widely investigated and are reported to be possible mediators of PRH, the pathogenesis is still not completely understood. In light of the important role of the gut microbiome in metabolism, we hypothesized that the gut microbiome might also be a critical link between RYGB and hypoglycemia. In this review, we mainly highlight the current possible factors predisposing individuals to PRH, particularly related to the gut microbiota, which may yield significant insights into the intestinal regulation of glucose metabolic homeostasis and provide novel clues to improve the treatment of type 2 diabetes mellitus.

Gut-brain crosstalk regulates craving for fatty food

Patients undergoing Roux-en-Y gastric bypass(RYGB)surgery elicit striking loss of body weight. Anatomical restructuring of the gastrointestinal(GI) tract, leading to reduced caloric intake and changes in food preference, are thought to be the primary drivers of weight loss in bariatric surgery patients. However, the mechanisms by which RYGB surgery causes a reduced preference for fatty foods remain elusive. In a recent report, Hankir et al described how RYGB surgery modulated lipid nutrient signals in the intestine of rats to blunt their craving for fatty food. The authors reported that RYGB surgery restored an endogenous fat-satiety signaling pathway, mediated via oleoylethanolamide(OEA), that was greatly blunted in obese animals. In RYGB rats, high fat diet(HFD) led to increased production of OEA that activated the intestinal peroxisome proliferation activator receptors-α(PPARα). In RYGB rats, activation of PPARα by OEA was accompanied by enhanced dopamine neurotransmission in the dorsal striatum and reduced preference for HFD. The authors showed that OEA-mediated signals to the midbrain were transmitted via the vagus nerve. Interfering with either the production of OEA in enterocytes, or blocking of vagal and striatal D1 receptors signals eliminated the decreased craving for fat in RYGB rats. These studies demonstrated that bariatric surgery led to alterations in the reward circuitry of the brain in RYGB rats and reduced their preference for HFD.