The Prevalence of Subclinical Iron Deficiency in Patients with Irritable Bowel Syndrome

Abstract

Purpose: Hemoglobin oxygenase-2 (HO-2) is a modulator of intestinal motility and its expression is affected by iron deficiency. Therefore, iron deficiency may be involved in the pathophysiology of irritable bowel syndrome (IBS). The prevalence of subclinical iron deficiency in the general population is 9-15%, but this prevalence is unknown in IBS patients. The aim of the current study is to explore the prevalence of subclinical iron deficiency in patients with IBS. Methods: The medical records of our institution were queried to identify patients with IBS from January 1, 2000 to January 1, 2013. Records of 1,000 patients were reviewed and those who were diagnosed by a gastroenterologist according to Rome criteria (II or III depending on the year of diagnosis) and had iron studies were included. We excluded patients with concurrent GI disorders other than gastroesophageal reflux and those with a history of gastrointestinal surgery. Patient demographics, IBS subtype (constipation IBS-C, diarrhea-predominant IBS-D, or mixed), and serum level of ferritin, hemoglobin, and hematocrit was extracted. ANOVA was used to test for differences in ferritin level based on IBS subtype. We used a serum ferritin level <26 ng/mL, which predicts depletion of iron stores with high sensitivity and specificity, and normal hemoglobin and hematocrit as definition of subclinical iron deficiency. Results: A total of 107 patients were included in the study, 93 (87%) females and 14 (13%) males. Mean age of female and male patients were 39 and 35 years old, respectively. Six patients were postmenopausal. Thirty-six patients were African American (34%) and 71 were Caucasians (66%). Forty patients (37%) had IBS-D, 27 (26%) had IBS-C, and 40 (37%) had mixed symptoms. The mean of serum ferritin level was 31.23 ng/dL in females and 121.5 ng/dL in males. Sixty-one (57%) females and 2 (2%) males had serum ferritin level <26 ng/dL. Mean age of these patients were similar to the whole group with 4 patients being postmenopausal. Of these patients, 6 females and 2 males had low hemoglobin and hematocrit while 55 (51%) had normal values, fulfilling the criteria for subclinical iron deficiency. Mean serum ferritin level in these patients was 11.53 ng/dL. ANOVA showed no significant difference between IBS subtypes (p= 0.741) or race (p=0.375) in patients with subclinical iron deficiency. Conclusion: This data suggests that the prevalence of subclinical iron deficiency is high in patients with IBS, regardless of race or subtype. About 50% of our patients had subclinical iron deficiency which is much higher than the prevalence reported in the general population. Further studies with larger sample sizes are required to investigate the role of iron deficiency in the pathogenesis of IBS.