The Prevalence of Vitamin B12, Hemoglobin, and Ferritin Deficiency in Patients with Morbid Obesity and Changes in their Blood Levels after Bariatric Surgery.

Background: Obesity and its complications are becoming a global concern. Assessing hemoglobin (Hb), vitamin B12, and ferritin deficiencies is crucial for morbidly obese patients due to the significant implications these deficiencies can have on their overall health and well-being. Studies indicate that individuals undergoing bariatric surgery are at a high risk of developing deficiencies in essential nutrients such as vitamin B12, iron, and folate, which can have profound health implications. One of the most effective treatments for morbidly obese patients is bariatric surgery. By understanding the process of these surgeries, several micronutrient deficiencies are anticipated. The lack of data about how bariatric strategies may affect these micronutrient levels provoked us to examine these changes closely.

Methods: In the current retrospective cohort study, we submitted 224 morbidly obese patients (body mass index (BMI) ≥ 40 kg/m2 or BMI = 35-39.9 kg/m2 with a risk factor, e.g. diabetes mellitus) who were candidates to bariatric surgeries at the obesity center of Rasoul-e-Akram Hospital from December 2018 to December 2019. Participants were divided into three groups of bariatric surgeries: sleeve gastrectomy (SG), mini-gastric bypass, and Roux-en-Y gastric bypass (RYGB). Demographics and clinical features and hemoglobin, ferritin, and vitamin B12 were recorded preoperatively and compared with postoperative follow-up periods at three, six, and 12 months after the operation.

Results: The mean age was 39.17 ± 10.60 years, and preoperative BMI was 46.13 ± 5.83 kg/m2. The prevalence of anemia was 7.1% before the surgery and 28.1% one year after. The results showed that hemoglobin level had been reduced within 12 months postoperatively, and the changes were statistically significant (P < 0.001). We were unable to find significant differences in the preoperative and postoperative proportions of anemia among different types of surgeries. Ferritin levels increased in the first three months after the operation and reduced as time went on. Preoperatively, 32.6% of the cases were ferritin deficient, which rose to 44.6% at the end of the 12-month follow-up. Vitamin B12 level was corrected by supplement therapy, and it did not reduce over follow-up periods (25% preoperatively vs. 21.9% at the end of the 12^th month). We found no meaningful differences among various types of surgery in examining vitamin B12 deficiency.

Conclusions: Bariatric surgery probably can increase the prevalence of anemia and ferritin deficiency. Vitamin B12 deficiency is expected after the surgery; however, it can be prevented by encouraging patients to use intramuscular or oral supplements during postoperative periods. Although micronutrient deficiencies can develop years after the surgery, a more significant study population must be designed with extended follow-up periods to determine more specific changes.