Algorithm to diagnose etiology of hypoglycemia after Roux-en-Y gastric bypass for morbid obesity: case series and review of the literature.

Background: Gastric bypass is a proven treatment option for weight loss and the reduction of medical co-morbid conditions in the obese population. Severe refractory and/or recurrent hypoglycemia can occur, especially in postoperative patients who do not comply with the guidelines for oral glucose consumption. In a very small number of patients, the cause is not dietary indiscretions but, instead, factitious insulin administration or nesidioblastosis. The optimal evaluation and management for these diagnoses is not completely lucid yet important for bariatric surgeons and physicians alike to be familiar. Our objectives were to review the appropriate evaluation and treatment options for etiologies of hypoglycemia after gastric bypass and to create an algorithm that biochemically assesses the etiology of hypoglycemia. The setting was a university hospital in the United States.

Methods: We present the cases of 3 patients who developed symptomatic hypoglycemia from distinct etiologies after laparoscopic Roux-en-Y gastric bypass. We also reviewed the current data regarding diagnosis and treatment.

Results: Each patient's evaluation and management is elaborated in detail. We propose a novel algorithm for the biochemical evaluation of hypoglycemia after gastric bypass according to our experience and the review of the literature.

Conclusion: Most cases of symptomatic hypoglycemia that develop in gastric bypass patients are associated with dietary indiscretions. However, a small subset of patients can develop refractory, recurrent, hyperinsulinemic hypoglycemia from factitious insulin administration or nesidioblastosis.