Review article|Articles in Press

Protein malnutrition after Roux-en-Y gastric bypass: a challenging case and scoping review of the literature

Published:December 27, 2022DOI:


      • Protein malnutrition (PM) is a rare complication after proximal Roux-en-Y gastric bypass (RYGB), reported in 1.7% of patients in the present review.
      • A structured diagnostic algorithm is necessary to promptly identify and manage potential causes of PM after RYGB, as hypoalbuminemia may have devastating consequences if left untreated.
      • The most common cause of PM remains insufficient oral intake; a minimal protein intake of 60 g/d and up to 1.5 g/kg ideal body weight per day should be ensured.
      • Acute triggering factors such as intractable vomiting, dysphagia and other functional problems may increase the risk of PM in patients with RYGB.
      • A structured diagnostic algorithm needs to be followed in order to promptly identify and manage potential causes of PM after RYGB, as hypoalbuminemia may have devastating consequences in these patients if left untreated.


      Although protein malnutrition (PM) is often reported after highly malabsorptive procedures, its exact incidence and mechanisms after Roux-en-Y gastric bypass (RYGB) are poorly understood. The aim of this study was to present a challenging clinical case of PM after RYGB and conduct a scoping review of the literature. Among the 18 studies with 3015 RYGB patients included in the review, the median incidence of PM was 1.7% (range, 0%–8.9%), and it was diagnosed 12 to 120 months after RYGB. The most common cause is insufficient oral intake of protein; however, in cases of persistent hypoalbuminemia, a thorough diagnostic workup needs to be performed. Risk factors for PM after RYGB include specific triggering events such as intractable vomiting and dysphagia, and a total alimentary limb length less than 250 to 300 cm.


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