Role of the Gastroenterologist in Managing Obesity

John K DiBaise; Amy E Foxx-Orenstein


Expert Rev Gastroenterol Hepatol. 2013;7(5):439-451. 

In This Article

Other Bariatric Surgery Complications Relevant to the Gastroenterologist

Nutritional and metabolic complications may also occur after bariatric operations. Approximately, 30% of bariatric surgery patients will develop a nutrition-related complication, typically a macronutrient or micronutrient deficiency or both, at some point following their operation (Table 6).[102] The most common nutritional deficiencies after bariatric surgery, particularly after the bypass operations, are iron, calcium, vitamin D and vitamin B12. Signs and symptoms that should prompt evaluation for nutrient deficiencies include anemia (iron, folate, vitamins B12, A and E, copper and zinc), metabolic bone disease (calcium, vitamin D), protein-energy malnutrition, steatorrhea, Wernicke's encephalopathy (thiamine), polyneuropathy and myopathy (thiamine, copper, vitamins B12 and E), visual disturbance (vitamins A and E, thiamine) and skin rash (zinc, essential fatty acids, vitamin A). The etiology of most nutritional deficiencies following bariatric surgery is multifactorial with contributions from reduced dietary intake, altered dietary choices and malabsorption. The number and severity of the deficiencies is determined by both the type of bariatric surgery performed, the dietary habits of the patient and the presence of other surgery-related GI complications such as nausea, vomiting or diarrhea. For example, in operations that result in the nutrient stream, bypassing the distal stomach, duodenum and proximal jejunum, malabsorption of iron, calcium, folate and vitamin B12 may be expected. The 'malabsorptive' procedures (i.e., BPD and very long-limb RYGB) may place the patient at higher risk of deficiency of fat-soluble vitamins, calcium, essential fatty acids, copper and zinc. Although some deficiencies may develop quickly, most are insidious in onset and may not be readily apparent clinically.

Routine postoperative nutritional monitoring and micronutrient supplementation is recommended in all bariatric patients but particularly after RYGB and BPD, as they are associated with more deficiencies over the long-term.[103,104] Because of the potentially devastating effects if not identified, if there is concern of possible thiamine deficiency in a bariatric surgery patient, parenteral thiamine should be administered immediately, and dextrose should be avoided in the intravenous hydration until the thiamine has been adequately replaced. For all bariatric surgery patients, a daily protein intake of 60–70 g/day, and daily multivitamin with iron and vitamin B12 supplementation is recommended. Daily calcium and vitamin D supplementation is also encouraged. Furthermore, serum micronutrient levels should be monitored regularly and additional supplementation prescribed as indicated. Currently, there is no consensus as to what represents the optimal supplementation regimen.

A metabolic complication infrequently seen after bariatric surgery is hyperinsulinemic hypoglycemia secondary to pancreatic islet cell hypertrophy, also referred to as nesidioblastosis.[105] For reasons incompletely understood, inappropriately high levels of insulin after a carbohydrate-rich meal are produced that cause glucose to fall to dangerously low levels. This condition typically presents a year or more after RYGB with recurrent episodes of dizziness, confusion and syncope or near-syncope caused by symptomatic hypoglycemia, usually within 1–2 h postprandially, and needs to be differentiated from late dumping syndrome.