{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T23:08:43Z","timestamp":1790723323754,"version":"4.1.0"},"reference-count":48,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,7,9]],"date-time":"2025-07-09T00:00:00Z","timestamp":1752019200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Nutr."],"abstract":"<jats:sec><jats:title>Background<\/jats:title><jats:p>Anemia is a common nutritional complication after bariatric surgery, deteriorating quality of life. Despite 10\u201330% of patients with obesity being anemic preoperatively, current guidelines do not recommend managing anemia before surgery. This study aims to evaluate the impact of preoperative anemia on postoperative anemia and related nutritional abnormalities.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Patients undergoing bariatric surgery at two bariatric centers from 2017 to 2021 were reviewed and followed for 1\u202fyear. Anemia was defined by WHO criteria. Nutritional abnormalities included ferritin, folate, and vitamin B12 deficiency, and low transferrin saturation (TS) levels.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>A total of 452 patients were included, of whom 53 (11.7%) were diagnosed with anemia before surgery. Patients with preoperative anemia were more likely to develop postoperative anemia (69.8% vs. 34.8%, <jats:italic>p<\/jats:italic>\u202f&amp;lt;\u202f0.001), ferritin deficiency (77.4% vs. 41.6%, <jats:italic>p<\/jats:italic>\u202f&amp;lt;\u202f0.001), and low TS levels (56.6% vs. 20.3%, <jats:italic>p<\/jats:italic>\u202f&amp;lt;\u202f0.001) than normal patients. Changes in hemoglobin, ferritin, folate, and vitamin B12 levels did not differ significantly between patients with preoperative anemia and normal patients. After fully adjusting for covariates, preoperative anemia was independently associated with postoperative anemia (OR 3.52, 95% CI 1.83\u20137.06, <jats:italic>p<\/jats:italic>\u202f&amp;lt;\u202f0.001), moderate to severe anemia (OR 5.03, 95% CI 2.48\u201310.20, <jats:italic>p<\/jats:italic>\u202f&amp;lt;\u202f0.001), ferritin deficiency (OR 3.77, 95% CI 1.74\u20138.17, <jats:italic>p<\/jats:italic>\u202f=\u202f0.001), and low TS levels (OR 4.12, 95% CI 2.16\u20137.84, <jats:italic>p<\/jats:italic>\u202f&amp;lt;\u202f0.001).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>Preoperative anemia significantly elevates the risk of postoperative anemia, especially moderate to severe cases, and increases the incidence of iron deficiency. It is crucial to actively screen for and correct preoperative anemia to enhance hemoglobin levels and prevent postoperative anemia.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fnut.2025.1616340","type":"journal-article","created":{"date-parts":[[2025,7,10]],"date-time":"2025-07-10T05:46:21Z","timestamp":1752126381000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":6,"title":["The impact of preoperative anemia on postoperative anemia and related nutritional abnormalities after bariatric surgery: a multicenter cohort study"],"prefix":"10.3389","volume":"12","author":[{"given":"Yuntao","family":"Nie","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"An","family":"Ping","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Baoyin","family":"Liu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hua","family":"Meng","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2025,7,9]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"e13516","DOI":"10.1111\/obr.13516","article-title":"Prevalence of anemia and related nutrient deficiencies after sleeve gastrectomy: a systematic review and meta-analysis","volume":"24","author":"Nie","year":"2023","journal-title":"Obes Rev"},{"key":"ref2","doi-asserted-by":"publisher","first-page":"e006964","DOI":"10.1136\/bmjopen-2014-006964","article-title":"Anaemia and related nutrient deficiencies after roux-en-Y gastric bypass surgery: a systematic review and meta-analysis","volume":"5","author":"Weng","year":"2015","journal-title":"BMJ Open"},{"key":"ref3","doi-asserted-by":"publisher","first-page":"1336","DOI":"10.1210\/jendso\/bvaa046.1336","article-title":"MON-595 severe copper deficiency post-bariatric surgery with serious preventable complications","volume":"4","author":"Aljaberi","year":"2020","journal-title":"Journal of the Endocrine Society"},{"key":"ref4","doi-asserted-by":"publisher","first-page":"199","DOI":"10.3748\/wjg.v28.i2.199","article-title":"Therapeutic endoscopy for the treatment of post-bariatric surgery complications","volume":"28","author":"Larsen","year":"2022","journal-title":"World J Gastroenterol"},{"key":"ref5","first-page":"294","article-title":"The role of pre-operative neutrophil-to-lymphocyte ratio in predicting post bariatric surgery related complications","volume":"22","author":"Mari","year":"2020","journal-title":"Israel Med Assoc J"},{"key":"ref6","doi-asserted-by":"publisher","first-page":"175","DOI":"10.1016\/j.soard.2019.10.025","article-title":"Clinical practice guidelines for the perioperative nutrition, metabolic, and nonsurgical support of patients undergoing bariatric procedures - 2019 update: cosponsored by American Association of Clinical Endocrinologists\/American College of Endocrinology, the Obesity Society, American Society for Metabolic & bariatric surgery, obesity medicine association, and American Society of Anesthesiologists","volume":"16","author":"Mechanick","year":"2020","journal-title":"Surg Obes Relat Dis"},{"key":"ref7","doi-asserted-by":"publisher","first-page":"e13087","DOI":"10.1111\/obr.13087","article-title":"British obesity and metabolic surgery society guidelines on perioperative and postoperative biochemical monitoring and micronutrient replacement for patients undergoing bariatric surgery-2020 update","volume":"21","author":"O'Kane","year":"2020","journal-title":"Obes Rev"},{"key":"ref8","doi-asserted-by":"publisher","first-page":"1664","DOI":"10.1016\/j.soard.2017.07.019","article-title":"Long-term nutritional impact of sleeve gastrectomy","volume":"13","author":"Caron","year":"2017","journal-title":"Surg Obes Relat Dis"},{"key":"ref9","doi-asserted-by":"publisher","first-page":"2606","DOI":"10.1007\/s11695-020-04528-x","article-title":"Evolution of hematological parameters during the first 2 years after laparoscopic sleeve gastrectomy: results of a retrospective study","volume":"30","author":"Kyio","year":"2020","journal-title":"Obes Surg"},{"key":"ref10","doi-asserted-by":"publisher","first-page":"1674","DOI":"10.1007\/s11695-017-2557-1","article-title":"Evaluation of vitamin and trace element requirements after sleeve gastrectomy at long term","volume":"27","author":"Pellitero","year":"2017","journal-title":"Obes Surg"},{"key":"ref11","doi-asserted-by":"publisher","first-page":"287","DOI":"10.1136\/jcp.2010.086991","article-title":"Disorders of iron metabolism. 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