[Predictive values of routine blood test results for iron deficiency in children]

Objective: To explore the predictive values of routine blood test results for iron deficiency (ID) screening in children. Methods: Routine blood test results and serum ferritin (SF) levels from 1 443 healthy children (862 boys, 581 girls) aged 6 months to 18 years, who were seen for well-child visits between June 2017 and May 2019 in Children's Hospital, Zhejiang University School of Medicine, were retrospectively analyzed. ID was defined as SF<20 μg/L, iron deficiency anemia (IDA) as ID with anemia (hemoglobin(Hb)<110 g/L at 6 months-5 years of age, Hb<120 g/L at 6-18 years of age), non-anemia ID as ID without anemia, non-ID anemia as SF≥20 μg/L with anemia, and healthy control subjects as those with SF≥20 μg/L but without anemia. The blood test results including Hb, mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), red blood cell distribution width (RDW), and the percentage of low hemoglobin density (LHD) of healthy control, non-anemia ID, non-ID anemia, and IDA groups were compared by analysis of variance (ANOVA) or non-parametric test, quantitative data were described as x±s or M(interquartile range), and receiver operating characteristic curve (ROC) analysis was applied to assess predictive values of routine blood test results and LHD for detecting IDA and ID. Results: Among 1 443 children with median age of 2.1(3.3) years, 1 061 children were in healthy control group, 292 in non-anemia ID group, 43 in non-ID anemia group and 47 in IDA group. The prevalence of ID was much higher than that of anemia (23.5% (339/1 443) vs. 6.2% (90/1 443) , χ(2)=169.76, P<0.01). Compared with control group, non-anemia ID group showed higher LHD (0.088 (0.093) vs.0.073 (0.068), P<0.01) and RDW (0.131±0.013 vs. 0.126±0.008, P<0.01), lower MCV ((80±4) vs. (83±4) fl, P<0.01) and MCHC values ((326±9) vs. (329±8) g/L, P<0.01). IDA group showed higher LHD (0.322(0.544)) and RDW (0.151±0.018), lower MCV ((73±6) fl) and MCHC values((309±14) g/L) than non-anemia ID group (all P<0.01). The area under curve (AUC) values of MCHC, LHD, RDW and MCV for detecting ID were 0.63 (95%CI: 0.60-0.67), 0.63 (95%CI:0.60-0.67), 0.67 (95%CI: 0.63-0.70) and 0.73 (95%CI: 0.69-0.76) respectively. With cutoff limits (MCV<80.2 fl, RDW>0.131 or MCHC<322 g/L), MCV, RDW and MCHC showed higher sensitivity for screening ID than hemoglobin (0.540, 0.469 and 0.336 vs. 0.139, χ(2)=121.70, 87.47, 35.56, all P<0.01). Conclusion: MCV, RDW and MCHC can be used to screen ID in primary health care settings.