Inflammation and iron status in bariatric surgery candidates

Abstract

Background: Iron homeostasis is disturbed by the systemic inflammation commonly encountered in morbid obesity. However, inflammatory markers have seldom been considered in studies investigating the prevalence of iron deficiency (ID) in bariatric surgery (BS) candidates. The objective of this study was to evaluate the prevalence of ID and anemia with ID in BS candidates, accounting for inflammatory status as measured using high sensitivity C-reactive protein (hs-CRP), and to further characterize indices of iron status in BS candidates with systemic inflammation.

Patients and methods: On the basis of ferritin, hemoglobin, and hs-CRP levels, iron status was categorized in 803 (85%) of 947 consecutive BS candidates. Ferritin<12 ng/mL in females and<15 ng/mL in males irrespective of hs-CRP level was classified as absolute-ID, whereas ferritin between those thresholds and 100 ng/mL was categorized as functional-ID (FID) if hs-CRP>3 mg/L. Anemia was defined as hemoglobin<12 or<13 g/dL in females and males, respectively. Additional iron and hematological indices were assessed in patients with FID.

Results: Prevalence of absolute- and functional-ID was 8.7 and 52.5%, respectively. Anemia was found in 11.2% of the cohort, 80% of which were associated with ID. Among patients with FID, transferrin saturation (T-Sat)<20% was common (70.0%) and associated with larger impairment of hematological indices.

Conclusion: The data show that when hs-CRP as inflammatory marker and ferritin as iron index are considered, impaired iron status could be identified in approximately two thirds of BS candidates. Furthermore, T-Sat<20%, especially along with ferritin<30 ng/mL, appear to be practical cut-offs to identify patients with FID with larger iron status impairment.

Keywords: Anemia; Bariatric surgery; Ferritin; Gastric bypass; Inflammation; Iron; Iron deficiency; Obesity; Sleeve gastrectomy.