Status of Iron Metabolism 10 Years After Roux-En-Y Gastric Bypass

Preventing and Managing Pre- and Postoperative Micronutrient Deficiencies: A Vital Component of Long-Term Success in Bariatric Surgery

Bariatric surgery (BS) is an effective treatment for severe obesity and its related comorbidities, such as type 2 diabetes and hypertension. However, the anatomical and physiological changes associated with these procedures significantly increase the risk of preoperative and postoperative micronutrient deficiencies, which can lead to severe complications such as anemia, osteoporosis, and neurological disorders. This narrative review examines the prevalence and clinical implications of micronutrient deficiencies in BS patients, as well as evidence-based strategies for their prevention and management. The most common deficiencies include iron, vitamin B12, folate, calcium, vitamin D, and fat-soluble vitamins (A, E, and K). Procedures with a hypoabsorptive component, such as Roux-en-Y gastric bypass (RYGB) and biliopancreatic diversion with duodenal switch (BPD/DS), pose higher risks of deficiencies compared to restrictive procedures like sleeve gastrectomy (SG). Effective strategies involve the preoperative correction of deficiencies, continuous monitoring, and tailored supplementation. However, long-term adherence to supplementation tends to decrease over time, influenced by behavioral and socioeconomic factors. Hence, preventing and managing micronutrient deficiencies are crucial for the long-term success of BS. While current guidelines provide valuable recommendations, many are based on low-certainty evidence, underscoring the need for more robust studies. A multidisciplinary approach, combined with innovative strategies, such as telemedicine, can enhance adherence and achieve sustainable clinical outcomes.

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

BACKGROUND

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.

METHODS

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.

RESULTS

Red blood cells (4.75 [4.59-4.96] 106/μL vs. 4.51 [4.25-4.83] 106/μL, p < 0.0001), hemoglobin (14.0 [13.3-14.7] g/dL vs. 13.0 [12.1-14.3] g/dL, p < 0.0001), and folic acid (7.4 [5.9-10.4] ng/ml vs. 6.0 [4.5-9.1] ng/mL, p = 0.01) were significantly lower, while anemia prevalence (6.52% vs. 28.99%, p < 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, p = 0.42) and TIBC values (351 [326-391] µg/dL vs. 345 [5311-387] µg/dL, p = 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]).

CONCLUSIONS

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.

Iron homeostasis in obesity and metabolic and bariatric surgery: a narrative review

Iron deficiency has been recognized as a potentially modifiable nutritional complication of metabolic and bariatric surgery (MBS) since prior to the turn of the century. Despite this, it remains the most common and clinically significant nutritional complication of this surgery with the potential to negate quality of life and the health benefits of surgical weight loss. This narrative review summarizes the current literature regarding iron deficiency as it relates to patients with severe obesity and those who undergo MBS. Advances in the clinical knowledge of iron homeostasis in severe obesity as a chronic disease, current diagnostic criteria for the diagnosis of iron deficiency in this patient population, the significance of preoperative iron deficiency, postoperative iron deficiency, and the status of supplementation and treatment will be reviewed with emphasis on gaps in knowledge and needed areas of further study.

Long-Term Outcomes of Iron Deficiency Before and After Bariatric Surgery: a Systematic Review and Meta-analysis

PURPOSE

This study reviews the prevalence of iron deficiency (ID) in bariatric surgery candidates and the long-term outcomes of the prevalence of ID after bariatric surgery.

MATERIALS AND METHODS

A systematic literature search and meta-analysis were performed in PubMed for articles published by August 31, 2022, including these search terms: bariatric surgery, metabolic surgery, weight loss surgery, obesity surgery, sleeve gastrectomy, gastric banding, gastric bypass, duodenal switch, duodenojejunal bypass, iron, iron deficiency, sideropenia, and hypoferritinemia. Fifty-seven studies examining a total of 26,328 patients with morbidly obese were included in this meta-analysis finally.

RESULTS

The results showed a prevalence of 17% of ID in bariatric surgery candidates and a prevalence of 14%, 17%, 26%, 34%, 23%, 38%, and 23% of ID at 1-, 2-, 3-, 4-, 5-, 8-, and 10-year follow-up after bariatric surgery, respectively. Additionally, the results showed a prevalence of 15%, 19%, 35%, 38%, 29%, 30%, and 23% of ID at 1-, 2-, 3-, 4-, 5-, 8-, and 10-year follow-up after Roux-en-Y gastric bypass, respectively; a prevalence of 12%, 12%, 15%, 31%, and 17% of ID at 1-, 2-, 3-, 4-, and 5-year follow-up after sleeve gastrectomy, respectively; and a prevalence of 19% of ID at 1-year follow-up after anastomosis gastric bypass.

CONCLUSION

As a result, preoperative evaluation and correction of ID may lead to better outcomes for bariatric surgery candidates. ID is also common in patients after bariatric procedures, especially RYGB. Long-term, even lifelong, medical and nutritional monitoring and tailored interventions are critical.

The relationship between anemia and obesity

INTRODUCTION

Obesity is linked to a variety of unfavourable outcomes, including anaemia, which is a serious global public health problem. The prevalence of obesity along with anaemia suggests a relationship between obesity and anaemia. Recent studies have demonstrated strong associations between anaemia and obesity, chronic diseases, ageing, hepato-renal impairment, chronic infection, autoimmune diseases, and widespread malignancy. Thus, the intersection point of obesity and anaemia is an important area of attention.

AREA COVERED

This paper reviews the pathophysiology of obesity and anaemia. Then, It deliberates the relationship between obesity and different types of anaemia and other clinical forms associated with anaemia.

EXPERT OPINION

Obesity, especially obesity-related to excessive visceral fat distribution, is accompanied by several disturbances at the endothelial, hormonal, and inflammatory levels. These disturbances induce activation of several mechanisms that contribute to the anaemic state. Over-weight patients with chronic anaemias are required to maintain the related vitamins and minerals at optimum levels and appropriate BMI. In addition, a regular clinical follow-up is essential to be scheduled to reduce the risk of complications associated with anaemia in obese patients.

DOES SLC11A2 GENE MUTATION ASSOCIATE WITH IRON-REFRACTORY IRON-DEFICIENCY ANEMIA AFTER BARIATRIC SURGERY?

ABSTRACT - BACKGROUND: After bariatric surgery, if there is iron-refractory iron-deficiency anemia (IRIDA) and does not respond to supplemental iron therapy, excluding other possible etiologies, genetic changes involved in iron metabolism should be considered. AIM: This study aimed to investigate the association of both mutations 1285G-C and 1246C-T, in the SLC11A2 gene, and the etiopathogenesis of anemia refractory to iron supplementation in patients undergoing bariatric surgery using Roux-en-Y gastric bypass (RYGB). METHODS: A case-control study was conducted, in which 100 patients were evaluated as Cases Group [subdivided into (i) with Anemia and (ii) without Anemia] and 100 individuals as Controls, comprising both sexes. Inherited and acquired causes of IRIDA were excluded. DNA was extracted from leukocytes of peripheral blood, and the regions that cover both mutations have been amplified by the molecular techniques such as polymerase chain reaction/restriction fragment length polymorphism. RESULTS: The 1285G-C mutation was not determined in any of the 400 alleles analyzed. Regarding the 1246C-T mutation, the wild CC genotype was found with a higher prevalence in the Control Group (34%) (OR 0.5475; 95%CI 0.2920-1.027; p=0.0827). The mutant TT genotype was found only in the Cases Group I (with Anemia) (13%). CONCLUSION: The results show the association between 1246C-T mutation, in the SLC11A2 gene, and the etiopathogenesis of IRIDA to iron supplementation in the evaluated sample. There are differences, at the molecular level, in patients with and without IRIDA after bariatric surgery using RYGB.

Iron supplementation following bariatric surgery: A systematic review of current strategies

Iron deficiency (ID) and iron deficiency anemia (IDA) are common following bariatric surgery; however, there are limited standardized treatment recommendations for their management. The purpose of this study was to review the current strategies for iron supplementation following bariatric surgery and assess their relative efficacy in managing ID and IDA. MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials were searched to January 2021. Primary outcomes of interest were prevention or improvement in ID or IDA with iron supplementation. Forty-nine studies with 12,880 patients were included. Most patients underwent Roux-en-Y gastric bypass (61.9%). Iron supplementation was most commonly administered orally for prevention of ID/IDA and was effective in 52% of studies. Both IV and oral iron were given for treatment of ID/IDA. Fifty percent (3/6) of the oral and 100% (3/3) of the IV supplementation strategies were effective at treating ID. Iron supplementation strategies employed following bariatric surgery are highly variable, and many do not provide sufficient iron to prevent the development of ID and IDA, potentially due to poor patient adherence. Further high-quality prospective trials, particularly comparing intravenous and oral iron, are warranted in order to determine the ideal dosage, route, and duration of iron supplementation.

Long-term risk of anaemia after bariatric surgery: results from the Swedish Obese Subjects study

BACKGROUND

Nutritional deficiencies, such as iron and vitamin B12 deficiencies, are potential adverse consequences of bariatric surgery. Long-term data on anaemia after bariatric surgery are largely lacking. We aimed to investigate the risk of anaemia, iron and vitamin B12 deficiency anaemia, and vitamin B12 deficiency over 20 years in individuals who had bariatric surgery or received usual obesity care.

METHODS

The prospective, controlled Swedish Obese Subjects study recruited people with obesity via recruitment campaigns in the mass media and at primary health-care centres, and was done at 480 primary health-care centres and in 25 surgical departments in Sweden. Eligible participants were aged 37-60 years and had a BMI of either 34 kg/m² or more (for men) or 38 kg/m² or more (for women). Participants were excluded if they had undergone previous bariatric surgery or had contraindicating conditions. Two main groups were formed: those who chose bariatric surgery, the type of which was determined by the operating surgeon, and a contemporaneously matched control group, created by use of 18 matching variables, who received usual non-surgical obesity care that ranged from lifestyle advice to no treatment. Haemoglobin concentration was measured during examination visits at baseline and at 1 year, 2 years, 3 years, 4 years, 6 years, 8 years, 10 years, 15 years, and 20 years of follow-up. Anaemia was defined as a haemoglobin concentration of less than 120 g/L for women and 130 g/L for men. The primary, non-specified outcome was the incidence of anaemia, and was assessed in the as-treated population, which comprised only patients who received the actual treatment. The associations between treatment type and anaemia are expressed as unadjusted hazard ratios (HRs) and HRs adjusted for age, sex, BMI, menopausal status, education, diabetes, and hypertension, with 95% CIs. This study is registered in ClinicalTrials.gov, NCT01479452, and is closed to new participants, with follow-up ongoing.

FINDINGS

Between Sept 1, 1987, and Jan 31, 2001, 6905 individuals were assessed for eligibility, of whom 5335 were eligible. Of these, we included 2007 patients who chose bariatric surgery (266 in the gastric bypass group, 1365 in the vertical-banded gastroplasty group, and 376 in the gastric banding group) and 2040 matched controls who received usual obesity care. During a maximum of 20 years and a median of 10 years (IQR 3-20) of follow-up, there were 133 anaemia events in the gastric bypass group, 359 in the vertical-banded gastroplasty group, 101 in the gastric banding group, and 261 in the control group. Compared with the control group (13 cases per 1000 person-years, 95% CI 11-14), the incidence of anaemia was higher in the gastric bypass group (64 cases per 1000 person-years, 53-74; HR 5·05, 95% CI 3·94-6·48; p<0·0001), the vertical-banded gastroplasty group (23 cases per 1000 person-years, 21-26; 2·67, 2·25-3·18; p<0·0001), and the gastric banding group (26 per 1000 person-years, 21-31; 2·76, 2·15-3·52; p<0·0001). These associations remained after adjustment.

INTERPRETATION

Our findings highlight the increased risk of anaemia after bariatric surgery and the importance of long-term compliance to nutritional supplementation and monitoring to enable prevention and early detection of serious nutritional deficiencies after bariatric surgery.

FUNDING

Swedish Research Council, the Swedish state under the agreement between the Swedish Government and the county councils, the Swedish Diabetes Foundation, the Swedish Heart-Lung Foundation, and the Novo Nordisk Foundation.

Iron Deficiency in Obesity and after Bariatric Surgery

Iron deficiency (ID) is particularly frequent in obese patients due to increased circulating levels of acute-phase reactant hepcidin and adiposity-associated inflammation. Inflammation in obese subjects is closely related to ID. It induces reduced iron absorption correlated to the inhibition of duodenal ferroportin expression, parallel to the increased concentrations of hepcidin. Obese subjects often get decreased inflammatory response after bariatric surgery, accompanied by decreased serum hepcidin and therefore improved iron absorption. Bariatric surgery can induce the mitigation or resolution of obesity-associated complications, such as hypertension, insulin resistance, diabetes mellitus, and hyperlipidemia, adjusting many parameters in the metabolism. However, gastric bypass surgery and sleeve gastrectomy can induce malabsorption and may accentuate ID. The present review explores the burden and characteristics of ID and anemia in obese patients after bariatric surgery, accounting for gastric bypass technique (Roux-en-Y gastric bypass-RYGB) and sleeve gastrectomy (SG). After bariatric surgery, obese subjects' iron status should be monitored, and they should be motivated to use adequate and recommended iron supplementation.

Iron Deficiency - Not Only a Premenopausal Topic After Bariatric Surgery?

Purpose

In our centre, specialized high dose multivitamin supplementation designed to meet the needs of patients after gastric bypass surgery is routinely recommended in the early postoperative period. The aim of the present study was to analyse whether iron supplementation prescribed in clinical practice is sufficient in both sexes and whether multivitamin supplementation standardized for women might potentially lead to iron overload in men.

Materials/Methods

This was a retrospective study covering the period up to 36 months after bariatric surgery. Three groups were compared (men, premenopausal and postmenopausal women). The iron status was evaluated employing serum ferritin concentrations.

Results

A total of 283 patients who had at least one follow-up visit between January 2015 and April 2018 at a specialized academic outpatient centre were included (71 men, 130 premenopausal women, 82 postmenopausal women). Thirty-six months after surgery, 33.3%, 68.4% and 54.5% of the men, pre- and postmenopausal women, respectively, were iron deficient. The preoperative prevalence of excess ferritin levels was 13.7% in premenopausal, 3.0% in postmenopausal women, 5.7% in men and declined in the following months.

Conclusion

Iron deficiency is very common after gastric bypass surgery, and even high dosages of multivitamin and mineral supplements might not be sufficient to prevent the development of iron deficiency. Men, pre- and postmenopausal women differ in their prevalence of iron deficiency which demands adapted iron dosage regimens based on the sex and the age. Iron overload is rare in all observed groups and highest in premenopausal women.

Graphical abstract

Iron Deficiency and Anemia 10 Years After Roux-en-Y Gastric Bypass for Severe Obesity

Iron deficiency with or without anemia is a well-known long-term complication after Roux-en-Y, gastric bypass (RYGB) as the procedure alters the gastrointestinal absorption of iron. Iron is essential for hemoglobin synthesis and a number of cellular processes in muscles, neurons, and other organs. Ferritin is the best marker of iron status, and in a patient without inflammation, iron deficiency occurs when ferritin levels are below 15 µg/L, while iron insufficiency occurs when ferritin levels are below 50 µg/L. Lifelong regular blood tests are recommended after RYGB, but the clinical relevance of iron deficiency and iron insufficiency might be misjudged as long as the hemoglobin levels are normal. The aim of this study was to explore the frequency of iron deficiency and iron deficiency anemia one decade or more after RYGB, the use of per oral iron supplements, and the frequency of intravenous iron treatment. Nine hundred and thirty patients who underwent RYGB for severe obesity at three public hospitals in Norway in the period 2003-2009 were invited to a follow-up visit 10-15 years later. Results from blood tests and survey data on the use of oral iron supplements and intravenous iron treatment were analyzed. Ferritin and hemoglobin levels more than 10 years after RYGB were available on 530 patients [423 (79.8%) women]. Median (IQR) ferritin was 33 (16-63) µg/L, and mean (SD) hemoglobin was 13.4 (1.3) g/dl. Iron deficiency (ferritin ≤ 15 µg/L) was seen in 125 (23.6%) patients; in addition, iron insufficiency (ferritin 16-50 µg/L) occurred in 233 (44%) patients. Mean (SD) hemoglobin levels were 12.5 (1.4) g/dl in patients with iron deficiency, 13.5 (1.2) g/dl in patients with iron insufficiency, 13.8 (1.3) g/dl in the 111 (21%) patients with ferritin 51-100 µg/L, and 13.8 (1.2) g/dl in the 55 (10%) patients with ferritin >100 µg/L. Two hundred and seventy-five (56%) patients reported taking oral iron supplements, and 138 (27.5%) had received intravenous iron treatment after the RYGB procedure. Iron deficiency or iron insufficiency occurred in two-thirds of the patients 10 years after RYGB, although more than half of them reported taking oral iron supplements.

Iron, Vitamin B12, Folate and Copper Deficiency After Bariatric Surgery and the Impact on Anaemia: a Systematic Review

Bariatric surgery may increase the risk of iron, vitamin B12, folate and copper deficiencies, which can cause anaemia. This review aims to critique the evidence on the prevalence of these nutritional deficiencies and the impact on anaemia in the first 12 months after surgery. PRISMA and MOOSE frameworks, the NHMRC evidence hierarchy and The Academy of Nutrition and Dietetics bias tool were used to systematically critique current literature. Seventeen studies reported on deficiency prevalence with the majority being of low quality. Important confounders to serum micronutrient levels were not adequately considered. Results on the prevalence of nutritional anaemias were also lacking. Further investigation into the prevalence of iron, vitamin B12, folate and copper deficiency and its impact on anaemia in bariatric surgery is needed.

The incidence of iron deficiency anemia post-Roux-en-Y gastric bypass and sleeve gastrectomy: a systematic review

SETTING

The physiological and anatomical changes that occur as a consequence of bariatric surgery result in macro- and micro-nutritional deficiencies, especially iron deficiency. The reported incidence of iron deficiency and associated anemia after bariatric surgery varies widely across studies.

OBJECTIVES

The aim of this systematic review is to quantify the impact of Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) on the incidence of iron deficiency.

METHODS

Databases including Ovid Medline, Ovid Embase, Helthstar, Scopus, Cochrane (CDSR), LILACS, and ClinicalKey were searched for original articles with additional snowballing search. Search terms included Obesity, nutrient deficiency, iron deficiency, iron deficiency anemia, bariatric surgery, Roux-en-Y gastric bypass, and sleeve gastrectomy. Original articles reporting the incidence of iron deficiency and anemia pre- and post-RYGB and SG from January 2000 to January 2015 with minimum 1-year follow-up were selected. Data extraction from selected studies was based on protocol-defined criteria.

RESULTS

There were 1133 articles screened and 20 studies were included in the final analysis. The overall incidence of iron deficiency was 15.2% pre-operatively and 16.6% post-operatively. When analyzed by procedure, the incidence of iron deficiency was 12.9% pre-RYGB versus 24.5% post-RYGB and 36.6% pre-SG versus 12.4% post-SG. The incidence of iron deficiency-related anemia was 16.7% post-RYGB and 1.6% post-SG. Risk factors for iron deficiency were premenopausal females, duration of follow-up, and pre-operative iron deficiency. Prophylactic iron supplementation was reported in 16 studies and 2 studies provided therapeutic iron supplementation only for iron-deficient patients. Iron dosage varied from 7 to 80 mg daily across studies.

CONCLUSION

Iron deficiency is frequent in people with obesity and may be exacerbated by bariatric surgery, especially RYGB. Further investigation is warranted to determine appropriate iron supplementation dosages following bariatric surgery. Careful nutritional surveillance is important, especially for premenopausal females and those with pre-existing iron deficiency.