Value of Serum Transferrin Receptor Levels in Assessing Iron Status in Patients with Inflammatory Bowel Disease

Background: It is difficult to assess iron status in patients with chronic inflammatory conditions such as inflammatory bowel disease (IBD). Currently available tests including serum ferritin and transferrin saturation have limitations in differentiating Iron Deficiency Anaemia (IDA) from Anaemia of Chronic Disease (ACD). Serum soluble transferrin receptor (sTfR) level has been proposed as a potential tool to identify iron deficiency in patients with chronic inflammation. sTfR levels are not influenced by inflammation and high levels are thought to represent iron deficiency. Methods: The aim of our study was to examine the value of sTfR in the assessment of iron status in patients with IBD. The study comprised of 154 patients with IBD, diagnosed on clinical, endoscopic, histological and/or radiological findings. They were compared with age and sex matched healthy controls (n=209). All patients and controls had blood investigations comprising haemoglobin (Hb), serum B12, red cell folate, ferritin, transferrin, serum iron and sTfR. Iron deficiency was considered to be present in anaemic patients ( IDA group ) if both ferritin and serum iron levels were low, < 15 ug/l and < 10 micromol/l respectively. Anaemic patients with normal or raised ferritin combined with either normal or low serum iron were classified as having ACD. Serum soluble transferrin receptor levels were measured by enzyme linked immunoassay from Orion Diagnostica. Results: Of the 154 patients, 61 patients were found to be anaemic based on the Hb thresholds as described above. A subgroup of 44 patients was ∗ Corresponding author: Professor Jayantha Arnold, Department of Gastroenterology, Ealing Hospital, Uxbridge Road, Southall, UB1 3HW THE WEST LONDON MEDICAL JOURNAL 2 classified as iron deficient (IDA) based on low ferritin or iron. 17 of the 61 anaemic patients were found to have a normal ferritin and serum iron. sTfR levels were not significantly different in the patients in the IDA group (n=44) 2.59 +/_ 1.48 mg/l compared with either patients in the ACD group ( with normal ferritin and serum iron ) (n=17) 1.67 +/_ 0.77 mg/l ( P>0.05 ) or with IBD patients without anaemia (n=93) 1.62 +/_ 0.78 mg/l ( P>0.05 ). These results were also not significantly different to healthy controls (n=209) 1.55 +/_ 0.60 mg/l. Conclusions: Anaemia is common in patients with inflammatory bowel disease. There were no significant differences in the sTfR levels in patients with inflammatory bowel disease irrespective of iron status compared with healthy controls. The early promise of sTfR as a useful tool in differentiating iron deficiency anaemia from anaemia of chronic disease has not been confirmed.