Iron absorption and serum ferritin in chronic inflammatory bowel disease.

Abstract

Iron absorption and serum ferritin concentration were studied in 44 patients with chronic inflammatory bowel disease (CIBD) (31 with Crohn's disease (CD) and 13 with ulcerative colitis (UC)), in 11 control subjects and in 3 patients with simple iron-deficiency anaemia. Iron absorption was determined from both whole body counting and red cell 59Fe incorporation following oral administration of 59FeCl3 with a small carrier dose (0.5 mg Fe). Serum ferritin was measured by a two-site immunoradiometric assay. Iron stores were estimated from the amount of stainable iron in sternal marrow. Normal range of iron absorption was 7–86%. In patients with CD and UC no correlation was present between iron absorption and disease activity, site of lesion, intestinal resection (no patient with severe short-bowel syndrome was studied), serum iron, transferrin, albumin or haemoglobin. In contrast, a significant and inverse correlation was found between iron absorption and serum ferritin, and a significantly positive correlation was found between serum ferritin and the iron content of sternal marrow. Following intravenous supply of 1 g iron (as iron-dextran) in 8 patients with CIBD, iron absorption decreased and serum ferritin increased, both on a statistically significant level. It is concluded that: (1) The ability to absorb iron is well preserved in CIBD, even in severe cases. (2) A decreased serum iron concentration does not imply an iron-deficiency state in CIBD. (3) Serum ferritin determination is a sensitive and little invasive way to assess whether a patient with CIBD is iron-deficient or not. (4) Parenteral supply of iron is in practice superior to oral iron medication in iron-deficient patients with CIBD.