title: Altered plasma response to zinc and iron tolerance test after Roux-en-Y gastric bypass.
abstract: BACKGROUND
  The duodenum and proximal jejunum are excluded after Roux-en-Y gastric bypass but these intestinal sites are where iron and zinc are most absorbed. Therefore, they are among the nutrients whose digestive and absorptive process can be impaired after surgery. The aim of the present study was to investigate the iron and zinc plasma response to a tolerance test before and after bariatric surgery. The study was performed at São Paulo University School of Medicine of Ribeirão Preto, Brazil.
  
  
  METHODS
  In a longitudinal paired study, 9 morbidly obese women (body mass index ≥40 kg/m(2)) underwent an iron and zinc tolerance test before and 3 months after surgery. The iron and zinc levels were determined at 0, 1, 2, 3, and 4 hours after a physiologic unique oral dose. The mineral concentrations in the plasma and 24-hour urine sample were assayed using an atomic absorption spectrophotometer. The anthropometric measurements and 3-day food record were also evaluated. A linear mixed model was used to compare the plasma concentration versus interval after the oral dose, before and after surgery.
  
  
  RESULTS
  The pre- and postoperative test results revealed a significantly lower plasma zinc response (P <.01) and a delayed response to iron intake after surgery. The total plasma iron concentration area, during the 4 hours, was not different after surgery (P >.05). The 24-hour urinary iron and zinc excretion did not differ between the pre- and postoperative phases.
  
  
  CONCLUSIONS
  The present data showed a compromised response to the zinc tolerance test after gastric bypass surgery, suggesting an impaired absorption of zinc. More attention must be devoted to zinc nutritional status after surgery.
authors.affiliation: Division of Medical Nutrition, Department of Internal Medicine, São Paulo University School of Medicine of Ribeirão Preto, Ribeirão Preto, São Paulo, Brazil. flaviarosa@usp.br
authors.forename: Flávia Troncon
authors.initials: FT
authors.lastname: Rosa
authors.forename: Fernanda Rodrigues
authors.initials: FR
authors.lastname: de Oliveira-Penaforte
authors.forename: Izabel
authors.initials: I
authors.lastname: de Arruda Leme
authors.forename: Gilberto João
authors.initials: GJ
authors.lastname: Padovan
authors.forename: Reginaldo
authors.initials: R
authors.lastname: Ceneviva
authors.forename: Julio Sérgio
authors.initials: JS
authors.lastname: Marchini
mesh_terms: D000328:Adult; D019587:Dietary Supplements; D004361:Drug Tolerance; D005260:Female; D005500:Follow-Up Studies; D015390:Gastric Bypass; D006801:Humans; D007501:Iron / Q000097:blood* / Q000652:urine; D019266:Iron, Dietary / Q000493:pharmacokinetics*; D009752:Nutritional Status; D009767:Obesity, Morbid / Q000178:diet therapy / Q000378:metabolism / Q000601:surgery*; D011184:Postoperative Period; D057234:Preoperative Period; D013054:Spectrophotometry, Atomic; D013997:Time Factors; D015032:Zinc / Q000097:blood* / Q000652:urine
chemical_list: D019266:Iron, Dietary; D007501:Iron; D015032:Zinc