Iron Deficiency Anemia Following Bariatric Surgery: A 10-Year Prospective Observational Study

The long-term follow-up studies investigating the risk of anemia and iron deficiency following bariatric procedures are scarce. This study aimed to determine the influence of body weight reduction and type of bariatric surgery on iron metabolism parameters. We included 138 consecutive patients who underwent bariatric surgery (120 underwent sleeve gastrectomy and 18 underwent other types of bariatric surgery) between 2010 and 2016. At baseline and at follow-up (median observation: 10 years), examination weight and height were measured, and blood samples for iron metabolism parameters were taken. Red blood cells (4.75 [4.59-4.96] 10 /μL vs. 4.51 [4.25-4.83] 10 /μL, < 0.0001), hemoglobin (14.0 [13.3-14.7] g/dL vs. 13.0 [12.1-14.3] g/dL, < 0.0001), and folic acid (7.4 [5.9-10.4] ng/ml vs. 6.0 [4.5-9.1] ng/mL, = 0.01) were significantly lower, while anemia prevalence (6.52% vs. 28.99%, < 0.0001) was significantly higher at the follow-up examination compared to the baseline values. In contrast, iron concentration (86.5 [68.0-109.0] µg/dL vs. 86.5 [55.0-110.0] µg/dL, = 0.42) and TIBC values (351 [326-391] µg/dL vs. 345 [5311-387] µg/dL, = 0.08) did not change significantly. The multivariable regression analyses showed that the only factors independently related to the hemoglobin concentration change were initial hemoglobin concentration, age, and bariatric procedures other than sleeve gastrectomy. Similarly, in the multivariable logistic analysis, the only variables independently related to the risk of anemia were age (adjusted odds ratio 0.93 [95% confidence intervals 0.89-0.97]), initial hemoglobin concentration (0.69 [0.49-0.97]), and procedures other than sleeve gastrectomy bariatric procedures (6.12 [1.86-20.15]). Age, initial hemoglobin concentration, and type of bariatric procedure but not sex, baseline iron serum level, or weight change are related to the risk of anemia in the long-term follow-up following bariatric surgery.