Obesity: Postsurgical Complications

How to Cite This Chapter: Tran S, Tiboni M, Prebtani APH. Obesity: Postsurgical Complications. McMaster Textbook of Internal Medicine. Kraków: Medycyna Praktyczna. https://empendium.com/mcmtextbook/chapter/B31.II. Accessed May 24, 2024.
Last Updated: June 22, 2021
Last Reviewed: June 22, 2021
Chapter Information

Dumping SyndromeTop

1. Definition: Dumping syndrome, also termed early dumping syndrome, refers to symptoms occurring within 15 to 30 minutes following consumption of a meal in the first 6 months following surgery. Patients experience gastrointestinal (GI) symptoms such as diarrhea, nausea, abdominal pain, abdominal distension, along with adrenergic symptoms such as diaphoresis, tachycardia, palpitations and a desire to lie down after eating. Dumping syndrome can also present with lightheadedness (as a result of hypotension) and rarely with syncope.

2. Incidence: It is estimated that up to 50% of patients after Roux-en-Y gastric bypass (RYGB) have dumping syndrome if they consume simple sugars.

3. Mechanism: Symptoms occur due to rapid movement of stomach contents into the small intestine after bariatric surgery, when large parts of the stomach are removed or bypassed. The hyperosmolar stomach contents cause fluid shifts from plasma to the bowel, leading to symptoms. Dumping syndrome can be exacerbated by a diet that is rich in simple sugars.

4. Diagnosis: Diagnosis can usually be made clinically, based on the timing of the patient’s bariatric surgery (dumping syndrome usually develops within 6 months after surgery) and symptom onset.

Diagnostic testing with an oral glucose tolerance test, gastric emptying study, upper GI endoscopy, or upper GI series are usually not required.

5. Treatment: Symptoms are usually self-limiting and conservative management is sufficient to treat dumping syndrome:

1) Avoiding foods rich in simple sugars.

2) Following a diet that is rich in fiber, complex carbohydrates, and proteins.

3) Eating small, frequent meals (eg, 5-6) throughout the day.

4) Separating liquid intake from meals by ≥30 minutes.

Referral to a bariatric specialist should be considered if symptoms do not improve.

Postprandial HypoglycemiaTop

1. Definition: Postprandial hypoglycemia, also termed late dumping syndrome or postprandial hyperinsulinemic hypoglycemia, refers to hypoglycemia occurring 1 to 3 hours following a meal, usually in patients ≥6 months following bariatric surgery; it can occur years after surgery. Patients have Whipple triad with documented hypoglycemia, neuroglycopenic symptoms (including weakness, fatigue, confusion, change in behavior, visual disturbances, loss of consciousness, or seizures) with or without adrenergic symptoms (including diaphoresis, palpitations, anxiety, and tremor) and prompt relief of symptoms after normalization of blood glucose.

2. Incidence: Postprandial hypoglycemia is more commonly diagnosed in patients post RYGB, with an estimated incidence of 0.1% to 0.3%, although this may be an underestimate due to a lack of recognition that symptoms may be related to hypoglycemia. Postprandial hypoglycemia can occur in patients with or without type 2 diabetes.

3. Mechanism: The pathophysiology of postprandial hypoglycemia is still being investigated and is believed to be multifactorial. Changes including an increased incretin response (eg, glucagon-like peptide 1 [GLP-1], glucose-dependent insulinotropic polypeptide [GIP]) to food ingestion, increased beta-cell sensitivity to GLP-1, increased insulin sensitivity after weight loss, and abnormal counterregulatory hormones lead to inappropriate hyperinsulinemia and resultant hypoglycemia after a meal.

4. Diagnosis: Diagnosis can usually be made clinically, based on the timing of the patient’s bariatric surgery and symptom onset. Fasting hypoglycemia should not be present; if present, an alternate diagnosis should be considered.

Diagnostic testing with a mixed meal test can be performed to document hypoglycemia (along with blood tests including insulin, C-peptide, proinsulin, and beta-hydroxybutyric acid levels; with the latter tests only being helpful if documented hypoglycemia occurs at the same time) following a meal. However, there is no standardized meal that has been developed in this patient population.

5. Treatment: Most patients can be managed with similar dietary advice as in early dumping syndrome.

If hypoglycemia persists, referral to a bariatric specialist should be considered. Further assessment can determine if medications such as acarbose, diazoxide, octreotide, or nifedipine would be beneficial. Patients with severe symptoms and impaired quality of life may require enteral nutrition through the remnant stomach or a revision surgery. Partial pancreatectomy has not been shown to reverse hypoglycemia and is no longer recommended.

Differentiation between dumping syndrome and postprandial hypoglycemia: Table 1.


Table 6.5-1. Differentiation between dumping syndrome and postprandial hypoglycemia

Dumping syndrome

Postprandial hypoglycemia

Also termed early dumping syndrome

Also termed late dumping syndrome

Occurs early in postoperative course (within 6 months)

Occurs ≥6 months, usually years after surgery

Symptoms within 15-30 min after a meal

Symptoms 1-3 h after a meal

Presents with adrenergic symptoms

Presents with neuroglycopenic ± adrenergic symptoms

Not associated with low blood glucose level

Associated with low blood glucose level

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