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P087. Measurement of reticulocyte and red blood cell indices in the evaluation of anemia in inflammatory bowel disease

P. Oustamanolakis1, I.E. Koutroubakis1, I. Messaritakis2, G. Kefalogiannis2, M. Niniraki3, E.A. Kouroumalis1

1Department of Gastroenterology, University Hospital, Heraklion, Crete, Greece; 2Laboratory of Hematology, University Hospital, Heraklion, Crete, Greece; 3Laboratory of Immunology, University Hospital, Heraklion, Crete, Greece

Background and Aim: Conventional markers of iron status cannot safely define iron deficiency anemia (IDA) in a chronic inflammatory setting. New generation indices have been introduced for the evaluation of anemia: Red blood cell Size Factor (RSF) is the square root of the product of MCV multiplied by the Mean Reticulocyte Volume (MRV) and seems to be a suitable parameter for the study of bone marrow erythropoietic activity. The Immature Reticulocyte Fraction (IRF) is an early and sensitive index of erythropoiesis. Reticulocyte Distribution Width (RDWR) is an indication of the size dispersion within the reticulocyte population. RDWR-SD is the standard deviation of the retic volume multiplied by the volume factor. RDWR-CV is the ratio of RDWR-SD and the retic volume mean multiplied by 100. The aim of this study was to investigate the usefullnes of reticulocyte and red blood cell indices in the evaluation of anemia in IBD.

Materials and methods: 100 consecutive IBD patients were included in the study (CD: 51, males: 58, mean age: 49 years, active disease: 20) and compared with 102 healthy controls (HC). All the full blood counts and RSF, IRF, RDWR-CV, RDWR-SD were processed using the COULTER® LH780 Hematology Analyzer (Beckman Coulter, Inc., CA, USA).

Results: Table 1 shows the laboratory parameters of patients compared with HC.

Table 1
Parameter Mean ± SDUCCDHCp
RDW15.4±2.315.9±2.413.7±1.1<0.0001
RSF96.7±7.697.4±11.297.6±5.30.82
IRF0.35±0.050.33±0.060.29±0.05<0.0001
RDWR-CV27.2±4.628.3±5.525.4±2.5<0.0001
RDWR-SD29.3±5.430.4±4.926.8±3.1<0.0001

The correlations between the examined markers and the markers of iron deficiency are presented in Table 2.

Table 2
 FerritinTsatsTfR
Parameterrprprp
RDW−0.100.32−0.39<0.00010.54<0.0001
RSF0.090.330.360.0002−0.54<0.0001
IRF0.090.38v0.010.330.010.88
RDWR-CV0.140.17−0.210.030.38<0.0001
RDWR-SD0.140.15−0.020.800.110.26

Patients with IDA were compared with those without IDA and the results are presented in Table 3.

Table 3
ParameterPatients with IDAPatients without IDAp
RDW17.0±2.115.1±2.20.0002
RSF91.9±10.199.1±8.50.0004
IRF0.32±0.060.34±0.050.19
RDWR-CV30.1±7.226.7±3.40.02
RDWR-SD30.1±4.229.7±5.50.53

The best markers for diagnosis of IDA were high values of RDW and low values of RSF. The sensitivity of high RDW for diagnosis of IDA using a cutoff of 14 was 93% and the specificity was 81%. Similarly, the sensitivity of low RSF for diagnosis of IDA using a cutoff of 97.6 was 80% and the specificity was 69%. Concerning disease activity, RDW and RSF were not significantly different between active and non active disease and no significant correlation between RDW or RSF and CRP levels was found (r = 0.16, p = 0.12 and r = −0.16, p = 0.12 respectively). A trend of correlation between IRF and CRP levels was found (r = 0.18, p = 0.06). A significant difference between active and non active disease was found for both RDWR-CV and RDWR-SD (p < 0.05). Moreover, a significant correlation between RDWR-CV or RDWR-SD and CRP was found (0.39, p < 0.0001 and r = 0.31, p = 0.001 respectively).

Conclusion: New generation indices (RSF, RDWR-CV) along with established markers (RDW) seem promising in the evaluation of anemia in IBD. Other new reticulocyte indices (IRF, RDWR-SD) may have a role in reflecting anemia mechanisms in IBD. Larger studies are needed to evaluate them in everyday clinical practice.