[Iron status of first-year junior high school students in rural boarding school among nine provinces in China]

To assess the iron status among boarding school students in a cross-sectional study performed in 9 provinces which were Beijing, Guangdong, Guangxi, Zhejiang, Tianjin, Ningxia, Sichuan, Shanghai and Shandong provinces.

A multi-stage cluster sampling survey on iron status of first-year junior high school students in rural boarding school in 9 provinces was used. Iron status was defined utilising biochemical indicators. Hemoglobin was measured by cyanmethemoglobin method. WS/T441-2013's hemoglobin thresholds used to define anemia. Immunoturbidimetric assay was used as analytical method for serum ferritin( SF), Serum soluble transferrin receptor( sTfR) and high sensitive C-reactive protein( hsCRP). BI was calculated by SF andsTfR. Storage iron depletion( SID) was defined as low SF( SF < 25 ng/mL) and low sTfR( sTfR < 4. 4 mg/L) without anemia. Iron deficient erythropoiesis( IDE) was defined as low SF( SF < 25 ng/mL) and high sTfR( sTfR > 4. 4 mg/L) without anemia. Iron deficiency anemia( IDA) was defined as low SF( SF < 25 ng/mL) with anemia. Subjects with indication of inflammation( hsCRP > 5 mg/L) were excluded from the analyses.

A total of 1263 adolescents aged 10-18 years( 696 boys and 567 girls) were involved. The levels of hemoglobin, serum ferritin, sTfR and BI concentration were( 144. 6 ± 13. 2) g/L, 52. 2 ng/mL, 3. 34 mg/L and( 6. 72 ± 2. 61) mg/kg for students, respectively. The overall prevalence of anemia was 4. 8%. The percentage of iron deficiency was 10. 5%, significantly higher in girls compared with boys. The overall percentage of SID, IDE and IDA was 6. 6%, 2. 5% and 1. 4%, respectively, with significant differences between boys and girls.

To ensure adequate iron stores, specific attention should be given to girls to ensure that their dietary intake of iron is adequate.