Iron deficiency in inflammatory bowel disease

The prevalence of iron-deficiency anemia was defined in 105 patients with inflammatory bowel disease and an appraisal made of the diagnostic value of serum ferritin for the assessment of iron stores. Iron deficiency, defined by the absence of bone-marrow hemosiderin was found with anemia in 36% of 41 patients with ulcerative colitis (UC) and 22% of 64 patients with Crohn's disease (CD). Iron deficiency without impaired erythropoiesis was detected in an additional 32% of patients with UC and 2% with CD. Anemia with plentiful bone-marrow iron was present in 33 (51%) of patients with CD, only one of whom had vitamin B12 deficiency. Red blood cell morphology, RBC indices, serum iron, and percent transferrin saturation correlated poorly with stainable marrow iron. Serum ferritin, assayed in samples from 45 patients, was <18 ng/ml in 4/12 with iron-deficiency anemia and 0/5 with absent marrow iron and a normal hemoglobin level; values >55 ng/ml were invariably associated with the presence of marrow hemosiderin. Based on a lower normal limit of 18 ng/ml, the serum ferritin had an excellent predictive value (100%) but a high predictive error (32%) in the diagnosis of iron deficiency in inflammatory bowel disease. Serum ferritin >55 ng/ml ruled out iron deficiency as the basis for anemia.