Trends of copper deficiency following one anastomosis gastric bypass and Roux-en-Y gastric bypass

Copper deficiency is an under-recognized complication after metabolic and bariatric surgery (MBS) with hematologic and neurologic sequelae. Comparative evidence between one-anastomosis gastric bypass (OAGB) and Roux-en-Y gastric bypass (RYGB) is limited. We compared time-dependent copper trends and deficiency prevalence after OAGB versus RYGB and identified associated factors.

We conducted a single-center retrospective cohort study of consecutive adults undergoing primary OAGB or RYGB (January 2020-December 2022). Serum copper was measured preoperatively and at 6 months and 12 months. Copper deficiency was defined as serum copper < 75 µg/dL. Multivariable logistic regression assessed associations of age, sex, procedure type, and 6-month percent total weight loss (%TWL) with deficiency; receiver operating characteristic (ROC) analysis explored a 6-month %TWL threshold.

Among 294 patients (OAGB n = 107; RYGB n = 187; mean age 38.8 ± 9.9 years; 83% women), deficiency prevalence across 6, and 12 months did not differ between procedures. Mean serum copper declined from baseline to 6 months in both groups and remained below baseline at 12 months. In adjusted analyses, female sex and greater 6-month %TWL were independently associated with copper deficiency at 6 months; age and procedure type were not. ROC analysis suggested an exploratory 6-month %TWL threshold of ~ 29% for identifying higher-risk patients (AUC 0.64). No consistent between-group differences were observed in hematologic or iron indices by copper status.

Copper deficiency rates through 12 months were comparable after OAGB and RYGB; however, mean serum copper declined after both procedures. Greater early weight loss was associated with deficiency, supporting targeted biochemical surveillance-particularly within the first postoperative year-and reinforcement of supplementation adherence.