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P240. Diagnosis of iron deficiency in inflammatory bowel diseases by transferrin receptor-ferritin index

V. Abitbol1, A. Esch1, D. Borderie2, V. Polin1, T. Tabouret1, M. Dhooge1, G. Perkins1, F. Maksimovic1, S. Chaussade1, 1Hôpital Cochin, Gastroenterology, Paris, France, 2Hôpital Cochin, Biochemistry Laboratory, Paris, France

Background

Iron deficiency (ID) is common in patients with inflammatory bowel disease (IBD) but can be difficult to diagnose in the presence of inflammation. Serum ferritin level <30 ng/mL is a diagnostic criterion of ID. Guidelines in IBD [1] consider ferritin level between 30–100 ng/mL associated with inflammation as criteria for ID diagnostic. The sTransferrin receptor-ferritin index (TfR-F) has a high sensitivity for ID diagnosis in chronic diseases [2]. The aim of the study was to assess the added value of TfR-F index to diagnosis of ID in a prospective cohort of IBD patients.

Methods

All consecutive IBD patients seen in our hospital from February to July 2013 were asked to participate in the study. Exclusion criteria were iron supplementation in the 3 previous months or lack of patient consent. IBD activity was assessed on symptoms and markers of inflammation (CRP, endoscopy, calprotectin). All patients had serum dosages of hemoglobin, hsCRP (N < 2.5 mg/L), ferritin (F), vitamins B9 and B12, LDH, haptoglobin. Soluble transferrin receptor (sTfR) was measured by Roche Tina-quant®. TfR-F index was calculated as the ratio sTfR/log F. ID was defined by F < 30 ng/mL or TfR-F index >2 in the presence of inflammation; TfR-F index <1 excluded ID.

Results

75 patients aged 38 (18–78) years, 40 males, 51 Crohn's disease (CD) and 24 ulcerative colitis (UC) were included. 35 patients (47%) had active disease. 25 patients (33%) had anemia (WHO criteria), including 14 CD and 11 UC. 4 patients (5%) had vitamin B12 deficiency and 4 (5%) vitamin B9 deficiency. No one had hemolysis. Mean F level was 76 (9–291) ng/mL and sTfR, 3.9 (1.6–12.8) mg/L. 21 patients (28%) had F < 30 ng/mL, 31 (41%) F between 30–100 ng/mL and 23 (31%) F > 100 ng/mL. 14 patients (19%) had F between 30–100 ng/mL and CRP > 2.5 mg/L: 1 had vitamin B12 deficiency excluding TfR-F analysis, 6/13 patients (46%) had TfR-F > 2. 1/12 (8.3%) patients with F > 100 ng/mL and CRP > 2.5 mg/L had TfR-F > 2. Overall, ID was diagnosed in 28/75 patients (37.3%), in which 28% on the basis of F < 30 ng/mL and 9.3% with TfR-F index >2 in the presence of inflammation.

Conclusion

This prospective study in IBD shows that TfR-F index in addition to serum ferritin <30 ng/mL criterion increases by 9.3% diagnosis rates of ID. Only 46% of the patients with ferritin between 30–100 ng/mL and inflammation have ID, suggesting that guidelines [1] overestimate ID in IBD. TfR-F index seems useful to ID diagnostic in IBD and prevents from overtreating by iron supplementation.

1. Gasche C et al, (2007), Guidelines on the Diagnosis and Management of Iron Deficiency and Anemia in Inflammatory Bowel Diseases, Inflamm Bowel Dis.

2. Weiss G et al, (2005), Anemia of Chronic Disease, The New England Journal of Medicine.