New concepts in the diagnosis and management approach to iron deficiency in candidates for metabolic surgery: should we change our practice?

Transferrin Saturation, Serum Ferritin, and C-Reactive Protein vs. Serum Ferritin for an optimal Iron Deficiency Diagnosis in Candidates for Bariatric Surgery

INTRODUCTION

Iron has different physiological processes and is regulated by hepcidin that is also an acute phase reactant, which increases with inflammation. Obesity produces a pro-inflammatory state, affecting directly the normal regulation of iron, causing ferritin (FER) deficiency. FER is used as the only indicator of the status of iron in patients with obesity, so the majority of them would be underdiagnosed, leading to a high prevalence of iron deficiency (ID) and anemia. The aim of this study is to evaluate the diagnostic tests: transferrin saturation (TS), FER, and C-reactive protein (CRP) vs. FER with the objective of analyzing the most accurate variable for the diagnosis of ID.

MATERIALS AND METHODS

We present a cross-sectional, analytical, and retrospective study, evaluating the diagnostic tests in 96 patients, to whom two methods were applied for the diagnosis of ID: method 1 (FER < 30 ng/mL) and method 2 divided into 2A (FER < 30 ng/mL), 2B (FER 30-100 ng/mL + CRP ≥ 5 mg/L), 2C (FER 100-300 ng/mL + CRP ≥ 5 mg/L + TS < 20%), and 2D (TS < 20%).

RESULTS

The prevalence of ID obtained using method 1 was 30.2% while 69.8% presented ID using total method 2, confirming an underdiagnosis of 39.6%.

CONCLUSION

The inflammatory state in patients with obesity must be considered in the diagnosis of ID. The use of TS, FER, and CRP has greater validity than the use of serum FER for the diagnosis of ID in patients with obesity.

Impact on oxidative stress of oral, high-dose, iron supplementation for management of iron deficiency after bariatric surgery, a preliminary study

OBJECTIVES

High-dose oral iron supplementation for patients who develop iron deficiency after bariatric surgery may induce oxidative stress in the gastrointestine. The study's objective was to test this hypothesis by determining the impact of high-dose oral iron on systemic oxidative stress.

METHODS

We used archived plasma samples from a randomized controlled clinical trial (NCT02404012) comparing FeSO4 (195 mg/day, NatureMade®, West Hills, CA) with a heme iron polypeptide (HIP, 60.4 mg/day, Proferrin®, Colorado Biolabs, Lafayette, CO) for 8 weeks. Systemic oxidative stress was measured using malondialdehyde and total antioxidant capacity (MDA, Abcam, ab238537 and TAC, Abcam, ab65329 Cambridge, UK) assays. Data was log-transformed and presented as means and standard deviations; a mixed model was used to determine the effects of time (0, 2, 4, and 8 weeks) and treatment (FeSO4 versus HIP) on oxidative stress.

RESULTS

The FeSO4 (N = 8) and HIP (N = 5) participants were balanced in body mass index (35.0 ± 5.5 kg/m2), race (93 % White), time post-surgery (7.3 ± 3.3 years), as well as serum concentrations of iron (P > 0.05). The FeSO4 group tended to be older (44.3 ± 4.5 years) and they had lower concentrations of serum ferritin (6.5 ± 2.7 µg/mL) than the HIP (38.2 ± 9.3 years, and 12.9 ± 16.8 µg/mL) group (P = 0.080, and P = 0.017 respectively). We observed a larger increase in serum iron in the FeSO4 group during the 8 weeks of Fe supplementation, compared to that in the HIP group (p = 0.004). We observed a decreasing trend in MDA over the 8 weeks (p = 0.080) in the FeSO4 treatment group. There were no significant differences in TAC between and within FeSO4 and HIP groups over the 8 week supplementation period.

CONCLUSIONS

This preliminary study suggests that high-dose oral iron supplementation for iron deficiency does not adversely impact systemic oxidative stress in patients undergoing bariatric surgery.

Clinical significance of iron deficiency among candidates for metabolic surgery

BACKGROUND

Iron deficiency (ID), a known complication after metabolic surgery, is common among preoperative patients in the presence of inflammation. Evidence is now accumulating that preoperative ID may adversely affect perioperative outcomes.

OBJECTIVES

To investigate the relationship between preoperative iron status and the risk of postoperative severe anemia. In addition, this study investigates the relationship between preoperative iron status and length of surgical stay SETTING: A large regional tertiary health system.

METHODS

Among patients who underwent metabolic surgery between 2004 and 2020, 5171 patients had a full iron nutritional assessment prior to surgery. Study patients were divided into multiple smaller groups (10 female groups and 7 male groups) on the basis of levels of serum ferritin and Transferrin Saturation (T Sat) < or ≥20%. Study patients were followed after surgery and the time to the development of severe anemia (hemoglobin < 8 gm/dL) was recorded. Hospital length of stay (LOS) was analyzed in relation to preoperative iron status.

RESULTS

Lower ferritin levels were associated with older age in males (P = .0001) and younger age in females (P < .0001). For males, after adjustment for age, body mass index (BMI), and year of surgery, surgical LOS was prolonged in those with T Sat <20% (P = .0041). For females the time until the development of severe anemia was associated with baseline iron status (P < .0001).

CONCLUSIONS

Male preoperative patients for metabolic surgery with T Sat <20% are at risk for increased surgical LOS. Females with low ferritin levels consistent with ID are at increased risk for the development of postoperative severe anemia.

Expert opinion on the preoperative medical optimization of adults with diabetes undergoing metabolic surgery

Diabetes mellitus (DM) and obesity are interrelated in a complex manner, and their coexistence predisposes patients to a plethora of medical problems. Metabolic surgery has evolved as a promising therapeutic option for both conditions. It is recommended that patients, particularly those of Asian origin, maintain a lower body mass index threshold in the presence of uncontrolled DM. However, several comorbidities often accompany these chronic diseases and need to be addressed for successful surgical outcome. Laparoscopic Roux-en-Y gastric bypass (RYGB) and laparoscopic sleeve gastrectomy (LSG) are the most commonly used bariatric procedures worldwide. The bariatric benefits of RYGB and LSG are similar, but emerging evidence indicates that RYGB is more effective than LSG in improving glycemic control and induces higher rates of long-term DM remission. Several scoring systems have been formulated that are utilized to predict the chances of remission. A glycemic target of glycated hemoglobin < 7% is a reasonable goal before surgery. Cardiovascular, pulmonary, gastrointestinal, hepatic, renal, endocrine, nutritional, and psychological optimization of surgical candidates improves perioperative and long-term outcomes. Various guidelines for preoperative care of individuals with obesity have been formulated, but very few specifically focus on the concerns arising from the presence of concomitant DM. It is hoped that this statement will lead to the standardization of presurgical management of individuals with DM undergoing metabolic surgery.

Assessment of baseline rates of functional and absolute iron deficiency in bariatric surgery candidates: a retrospective study

BACKGROUND

Preoperative optimization of iron status is a priority in candidates for bariatric surgery. Inflammation is strongly associated with obesity, and as a consequence, functional iron deficiency (ID) is potentially an underreported issue in surgical candidates.

OBJECTIVES

In light of updated practice guidelines, to retrospectively review preoperative iron status in an Irish cohort of bariatric surgery candidates, taking account of the relative incidence rate of functional ID.

SETTING

A tertiary care obesity service with bariatric surgery referral in Ireland.

METHODS

Baseline nutritional biochemistry records were reviewed between February 2017 and February 2020 in a hospital, Dublin, Ireland. Absolute ID was defined as serum ferritin <30 μg/L; functional ID was defined as ferritin, 30 to 100 μg/L, in the presence of C-reactive protein >5 mg/L. Anemia was indexed with reference to hemoglobin and qualified by vitamin B12 and folate status to rule out anemia unrelated to primary ID.

RESULTS

The analysis included 120 patients, 68% female, 49.6 ± 9.3 years, and body mass index, 52.0 ± 9.6 kg/m². The prevalence of absolute and functional ID was 11.7% and 30.8%, respectively (P = .0003). Anemia was associated with absolute ID and functional ID in 14.3% and 10.8% of patients (P = .29). Folate and vitamin B12 deficiency occurred in <5% of patients.

CONCLUSION

In patients seeking bariatric surgery for severe obesity, the prevalence of baseline functional ID is substantial and can be associated with anemia. These findings raise queries with regard to how best to optimize preoperative iron status in the context of ongoing inflammation.

Iron deficiency is highly prevalent among candidates for metabolic surgery and may affect perioperative outcomes

BACKGROUND

The presence of chronic low-grade inflammation, commonly identified in patients with severe obesity, alters iron homeostasis and indicators of iron status, fostering the development of updated guidelines for the diagnosis of iron deficiency (ID). Current recommended diagnostic thresholds for ID in obesity derived from expert opinion include a ferritin level of <30 ng/mL and/or transferrin saturation (TSAT) < 20%. Earlier studies of ID among candidates for metabolic surgery using low levels of ferritin or iron as diagnostic thresholds demonstrated a prevalence of 5%-20%.

OBJECTIVES

Using the current recommended diagnostic thresholds for ID, this study measures the prevalence of ID in a large cohort of surgical candidates and its relationship to surgical outcomes.

SETTING

Geisinger Medical Center, Danville, Pennsylvania.

METHODS

The study cohort included 3,723 patients who underwent pre- operative nutritional assessment which included markers of iron nutrition over the period 2004-2018.

RESULTS

The cohort included 2,988 women (80.3%) and 735 men (19.7%); body mass index: 49.4 ± 9 kg/m². The diagnosis of ID was based on ferritin level <30 ng/mL (true ID) and/or TSAT < 20% representing a combination of true ID and inflammation (serum ferritin ≥ 30 ng/mL and TSAT < 20%). A total of 399 patients (10.8%) were anemic. A serum ferritin level of < 30 ng/mL was found in 488 patients (13%; 481 women and 7 men). Of these, 122 patients (25.2%) were also anemic. An additional 1,204 had serum ferritin ≥ 30 ng/mL and TSAT < 20%. Overall, 1,692 patients (45.4%) in this cohort had laboratory evidence of ID by current criteria that adjusts for the very high prevalence of inflammation. Men with serum ferritin levels ≥30 ng/mL with TSAT < 20% had an increased surgical length of stay.

CONCLUSION

The prevalence of ID among surgical candidates (45.4%) is more than twice that identified as ID in earlier studies. ID was commonly identified in the absence of anemia. The most severe ID was found in those with a serum ferritin level <30 ng/mL and TSAT < 20%. ID in the presence of inflammation is often unrecognized and has implications regarding surgical outcomes after metabolic surgery.