Soluble transferrin receptor-ferritin index in the evaluation of anemia in inflammatory bowel disease: a case-control study

BACKGROUND: No reliable biochemical markers exist for the differentiation between iron deficiency anemia (IDA) and anemia of chronic disease (ACD) in the setting of inflammatory bowel disease (IBD). The aim of this study was to investigate the use of soluble transferrin receptor (sTfR) and sTfR-ferritin (sTfR-F) index in the evaluation of anemia in patients with IBD. METHODS: One hundred IBD patients [49 ulcerative colitis (UC), 51 Crohn’s disease (CD)] and 102 healthy controls were enrolled. Serum levels of ferritin, transferrin saturation and sTfR were analyzed in all patients and controls. sTfR-F index was calculated based on the ratio: sTfR/ log ferritin. The value of sTfR and sTfR-F for diagnosis of IDA was assessed. RESULTS: Forty two IBD patients (41% of UC and 42.9 % of CD) fulfilled the WHO criteria for the diagnosis of anemia. Among them thirty (30 %) had IDA, four (4%) had ACD and eight (8%) had mixed IDA/ACD. Patients with IDA had significantly higher sTfR and sTfR-F index levels compared with those without IDA (P<0.0001). Both sTfR and sTfR-F index were not correlated with CRP levels or disease activity. High sTfR levels (>1.8 mg/L) had sensitivity 81% and specificity 80%, whereas high sTfR-F index (>1.4) had sensitivity 91% and specificity 92% for the diagnosis of IDA. CONCLUSION: These results suggest that the sTfR-F index seems to be very efficient in the detection and diagnosis of IDA, among patients with IBD.