The real diagnostic value of serum iron in iron deficiency anemia among patients with inflammatory bowel disease: A retrospective study.

ObjectiveThe diagnostic utility of serum iron in identifying iron deficiency anemia among patients with inflammatory bowel disease remains underreported. This study aimed to evaluate the true diagnostic value of serum iron.MethodsA total of 160 patients with iron deficiency anemia from a grade-A general hospital in Sichuan Province between January 2022 and January 2025 were enrolled. Eighty patients with inflammatory bowel disease and iron deficiency anemia were included in the test group, while 80 patients with iron deficiency anemia without inflammation were included in the control group. Iron metabolism parameters, including serum iron and serum ferritin, complete blood count indices, and biochemical markers, were collected and compared. Differences in diagnosing iron deficiency anemia using serum iron and serum ferritin among patients with inflammatory bowel disease were compared using the chi-square test. Spearman correlation analysis was performed among serum iron, serum ferritin, and other indicators. Meanwhile, potential factors affecting serum iron levels were investigated using linear regression, and the significance of serum iron in diagnosing inflammatory bowel disease with iron deficiency was evaluated using the receiver operating characteristic curve.ResultsAmong patients with inflammatory bowel disease, ulcerative colitis and Crohn's disease showed no significant differences in serum iron and serum ferritin levels. The real clinical results showed that when using 1-6.6 times the lower limit of normal of serum ferritin as a threshold to diagnose patients with inflammatory bowel disease and iron deficiency anemia, a statistically significant difference was observed compared with the serum iron lower limit of 1 time (p < 0.01). The positivity rate of iron deficiency anemia was 88.75% (71/80) for serum iron and 61.25% (49/80) for 3.3-time serum ferritin. Correlation analysis revealed that serum iron was positively correlated with serum ferritin (r = 0.263, p = 0.018) and negatively correlated with most inflammatory parameters (p < 0.05). Multiple linear regression analysis showed that when serum iron was used as the dependent variable, the optimal regression model with the independent variables serum ferritin, hemoglobin, platelet count, and monocyte-to-lymphocyte ratio had regression coefficients (β) of 0.246, 0.231, -0.405, and -0.187, respectively, all of which were significantly different (p < 0.05). Moreover, according to the European Crohn's and Colitis Organization diagnostic criteria for iron deficiency, patients with inflammatory bowel disease were divided into an iron deficiency group involving 41 patients and a non-iron deficiency group involving 39 patients. By comparing the parameters of the two groups and constructing the receiver operating characteristic curve, serum iron alone yielded the highest Youden index and the largest area under the curve for diagnosing iron deficiency (area under the curve = 0.764, p < 0.001). However, when the false-positive rate was controlled at 20%, the sensitivity of serum iron for diagnosing iron deficiency was 62.00%.ConclusionsIn patients with inflammatory bowel disease, serum iron is inversely associated with inflammation and appears to be more sensitive than serum ferritin in detecting iron deficiency anemia. These findings suggest that combined measurement of serum iron and serum ferritin may enhance the diagnosis of iron deficiency anemia in clinical practice.