Iron studies are difficult to interpret in patients with chronic inflammatory states such as inflammatory bowel disease (IBD). Serum transferrin receptor (TfR) has been reported to be a reliable tool for the diagnosis of iron deficiency in adults. Our aim was to evaluate the role of serum TfR in diagnosing iron deficiency in children and adolescents with IBD. A total of 63 consecutive patients with IBD, aged 9 to 22 years (median 15 years), were tested for serum haemoglobin level, mean corpuscular volume (MCV), and serum iron, transferrin, ferritin and serum TfR levels. Those found to be anaemic were compared with seven age-matched subjects with iron deficiency anaemia (IDA) and 24 age-matched children without signs of anaemia or inflammation. Of the 63 patients with IBD, 26 had anaemia. Based on ferritin levels and MCV indices, anaemia was classified as IDA in 11 patients and as anaemia of chronic disease (ACD) in 15 patients. Mean serum TfR level in normal controls was 3.5 mg/l (range 1.2-8.2 mg/l). Mean (+/-SD) serum TfR levels were significantly lower in the IBD patients with ACD (5.3 +/- 2.3 mg/l) than in the IBD patients with IDA (8.2 +/- 3.1 mg/l) (P < 0.05). Serum TfR levels above 5 mg/l identified 10/11 IBD patients with IDA. The calculated TfR/ferritin ratio was 84 (range 17-367) for controls and 133 (range 6.4-1840) for IBD patients. A cut-off level of 350 (91% sensitivity, 100% specificity, 100% positive predictive value, 98% negative predictive value) was established for the diagnosis of IDA in IBD.
Conclusion: The results suggest that serum transferrin receptor is a useful parameter for the diagnosis of iron deficiency in inflammatory bowel disease, in particular, the transferrin receptor/ferritin ratio with a cut-off level > or = 350.