# Preplanned Studies: Iron Status Among Children Aged 6−17 Years by Serum Ferritin — China, 2016−2017

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• ### Summary

What is already known on this topic?

Iron deficiency (ID) is the most widespread micronutrient deficiency and have several adverse effects on health. Consequences of ID among children include delayed psychomotor development and impaired cognitive performance, which makes it important to monitor the iron status of children.

What is added by this report?

In this study, the serum ferritin (SF) level was 56.6 (95% CI: 56.0–57.2) ng/mL in 65,293 children aged 6–17 years old in the National Nutrition and Health Surveillance in China in 2016–2017. ID prevalence varied significantly in children stratified by sex, age, and regions ranging from 1.0% to 28.1% judged by the standard of SF<15 ng/mL and SF<25 ng/mL. ID prevalence in females aged 12–17 years was the highest among children aged 6–17 years.

What are the implications for public health practice?

Understanding iron status of school children could provide evidence and data for developing policies and strategies for ID and iron deficiency anemia (IDA) control and prevention. Females aged 12–17 years showed high ID prevalence, and iron-rich food interventions are strongly recommended.

•  [1] Beard JL. Iron biology in immune function, muscle metabolism and neuronal functioning. J Nutr 2001;131(2):568S − 80S. http://dx.doi.org/10.1093/jn/131.2.568SCrossRef [2] Sachdev H, Gera T, Nestel P. Effect of iron supplementation on mental and motor development in children: systematic review of randomised controlled trials. Public Health Nutr 2005;8(2):117 − 32. http://dx.doi.org/10.1079/phn2004677CrossRef [3] World Health Organization. Assessing the iron status of populations: including literature reviews: report of a Joint World Health Organization/Centers for Disease Control and Prevention Technical Consultation on the Assessment of Iron Status at the Population Level, Geneva, Switzerland, 6-8 April 2004, 2nd ed. Geneva: World Health Organization; 2007. https://apps.who.int/iris/handle/10665/75368. [2021-03-10]. [4] Pfeiffer CM, Looker AC. Laboratory methodologies for indicators of iron status: strengths, limitations, and analytical challenges. Am J Clin Nutr 2017;106(S6):1606S − 14S. http://dx.doi.org/10.3945/ajcn.117.155887CrossRef [5] Yu DM, Zhao LY, Zhang J, Yang ZY, Yang LC, Huang J, et al. China nutrition and health surveys (1982–2017). China CDC Wkly 2021;3(9): 193-5. http://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2021.058. [6] The Minister of Health of the People’s Republic of China. WS/T 465-2015 Method for iron deficiency screen. Beijing: Standards Press of China, 2015. http://www.nhc.gov.cn/wjw/yingyang/201505/2bd3ce9e38b043e7911da4ee1caac23d.shtml. (In Chinese). [7] Ferrari M, Mistura L, Patterson E, Sjöström M, Díaz LE, Stehle P, et al. Evaluation of iron status in European adolescents through biochemical iron indicators: the HELENA Study. Eur J Clin Nutr 2011;65(3):340 − 9. http://dx.doi.org/10.1038/ejcn.2010.279CrossRef [8] Yu D, Huo JS, Xie LB, Wang LJ. Meta-analysis of studies on cut-off value of serum ferritin for identifying iron deficiency. J Hyg Res 2013, 42(2):228-35. https://kns.cnki.net/kcms/detail/detail.aspx?FileName=WSYJ201302013&DbName=CJFQ2013.(In Chinese). [9] Lynch S, Pfeiffer CM, Georgieff MK, Brittenham G, Fairweather-Tait S, Hurrell RF, et al. Biomarkers of nutrition for development (BOND)-iron review. J Nutr 2018;148(S1):1001S − 67S. http://dx.doi.org/10.1093/jn/nxx036CrossRef [10] Piao JH, Huo JS. Report on China nutrition and health surveillance (2010–2013): resident physique and nutrition. Beijing: People’s Medical Publishing House. 2019. (In Chinese). [11] Lin XM, Wang Z, Shen XY, Long Z, Liu WJ, Guo YM, et al. Iron status and effect of early iron supplementation on sub-clinical iron deficiency in rural school-age children from mountainous areas of Beijing. Chin J Prev Med 2003;37(2):115-8. https://kns.cnki.net/kcms/detail/detail.aspx?FileName=ZHYF200302015&DbName=CJFQ2003. (In Chinese). [12] Chen QH, Pei CC, Bai YL, Zhao QR. Impacts of nutrition subsidies on diet diversity and nutritional outcomes of primary school students in rural northwestern China-Do policy targets and incentives matter? Int J Environ Res Public Health 2019;16(16):2891. http://dx.doi.org/10.3390/ijerph16162891CrossRef [13] Huo JS, Yin JY, Sun J, Huang J, Lu ZX, Regina MP, et al. Effect of NaFeEDTA-fortified soy sauce on Anemia prevalence in China: a systematic review and meta-analysis of randomized controlled trials. Biomed Environ Sci 2015;28(11):788 − 98. http://dx.doi.org/10.3967/bes2015.110CrossRef
• TABLE 1.  Serum ferritin levels for children aged 6–17 years — China, 2016–2017 (ng/mL).

 Age group (years) Total Urban Rural n $\bar{{{x}}}$G 95% CI n ${\bar{{x}}}$G 95% CI n $\bar{{{x}}}$G 95% CI 6–17 Total 65,293 56.6 56.0–57.2 30,960 57.9 57.0–58.8 34,333 55.5§ 54.7–56.2 Male 32,503 66.4 65.5–67.2 15,404 69.4 68.0–70.7 17,099 63.8§ 62.8–64.9 Female 32,790 47.3* 46.5–48.0 15,556 47.2* 46.1–48.4 17,234 47.3* 46.3–48.2 6–11 Subtotal 36,596 60.4 59.8–61.1 17,423 62.0 60.9–63.1 19,173 59.3§ 58.5–60.2 Male 18,223 60.5 59.6–61.5 8,665 62.2 60.7–63.8 9,558 59.3§ 58.1–60.6 Female 18,373 60.3 59.4–61.3 8,758 61.7 60.2–63.3 9,615 59.3§ 58.2–60.5 12–17 Subtotal 28,697 53.1 52.2–54.0 13,537 54.8 53.5–56.2 15,160 51.3§ 50.2–52.5 Male 14,280 72.7† 71.3–74.2 6,739 75.8† 73.7–78.1 7,541 69.6†§ 67.8–71.4 Female 14,417 37.6*† 36.7–38.6 6,798 38.5*† 37.2–40.0 7,619 36.7*b§ 35.5–37.9 Abbreviation: CI=Confidence Interval; $\overline x$G=geometric means. * P-value <0.05 for differences between male and female at same age group.† P-value <0.05 for differences between children 6–11 years and 12–17 years.§ P-value <0.05 for differences between urban and rural areas.

TABLE 2.  Median and selected percentiles of serum ferritin concentrations for children aged 6–17 years in China in 2016–2017 (ng/mL).

 Age group (years) P2.5 P5 P10 P25 P50 P75 P90 P95 P97.5 Total 6–17 Total 9.8 15.2 23.4 38.7 59.9 89.6 131.8 166.3 203.9 Male 17.9 23.1 30.3 45.0 66.5 100.3 147.7 188.3 225.7 Female 7.0 10.3 16.9 32.2 52.5 79.2 112.4 137.3 165.4 6–11 Subtotal 19.1 24.0 30.5 43.1 61.4 86.1 119.3 146.1 179.4 Male 19.3 24.1 30.5 43.3 61.2 84.9 119.7 148.2 187.8 Female 18.8 23.9 30.4 43.0 61.7 87.2 118.7 142.6 171.0 12–17 Subtotal 7.2 10.7 17.1 33.4 58.0 93.9 144.1 181.2 221.8 Male 16.7 21.8 30.1 47.6 75.1 118.2 171.5 212.7 251.8 Female 5.2 7.3 11.0 22.7 42.7 68.9 102.7 131.2 160.6 Urban 6–17 Total 9.2 14.5 22.5 38.3 61.4 95.5 141.0 181.0 220.7 Male 17.6 22.8 30.3 45.6 69.5 108.2 159.1 206.1 246.3 Female 6.5 9.7 15.6 31.2 52.7 81.4 118.6 146.2 177.8 6–11 Subtotal 18.2 23.4 30.0 43.3 63.1 90.8 125.9 158.7 197.5 Male 18.5 23.5 30.5 43.3 62.4 91.0 127.6 168.7 206.1 Female 17.8 23.3 29.6 43.2 63.6 90.8 125.0 153.3 189.1 12–17 Subtotal 7.0 10.7 17.2 33.7 59.6 100.1 152.3 193.5 236.1 Male 16.8 22.3 30.3 48.5 79.6 124.8 181.0 224.7 262.5 Female 5.2 7.1 11.2 22.9 43.5 71.4 111.6 142.0 170.4 Rural 6–17 Total 10.5 16.0 24.0 39.1 58.9 85.1 122.6 153.0 184.4 Male 18.1 23.4 30.3 44.4 64.3 93.1 138.3 172.9 205.2 Female 7.4 10.8 17.9 33.2 52.4 76.9 105.9 129.0 152.5 6–11 Subtotal 19.9 24.5 30.8 43.0 60.1 83.5 113.8 138.6 166.7 Male 20.1 24.5 30.5 43.3 60.1 81.9 114.4 140.5 168.9 Female 19.7 24.5 31.1 42.7 60.1 85.0 113.6 136.8 161.4 12–17 Subtotal 7.4 10.7 17.1 33.2 56.4 88.1 134.5 171.6 206.1 Male 16.3 21.4 29.8 46.7 71.6 109.6 161.1 198.4 231.6 Female 5.2 7.4 10.8 22.4 41.9 66.3 95.4 118.0 141.5

TABLE 3.  Iron deficiency prevalence for children aged 6–17 years — China, 2016–2017 [% (95% CI)].

 Age group (years) SF<25 ng/mL SF<15 ng/mL Total Urban Rural Total Urban Rural 6–17 Total 11.2(10.8, 11.6) 11.8(11.2, 12.4) 10.6(10.1, 11.2)§ 4.9(4.6, 5.2) 5.4(4.9, 5.8) 4.5(4.1, 4.9)§ Male 6.1(5.7, 6.6) 6.3(5.7, 7.0) 5.9(5.4, 6.6) 1.6(1.4, 1.9) 1.8(1.5, 2.2) 1.4(1.2, 1.8) Female 16.9(16.2, 17.6)* 18.0(16.9, 19.0) * 16.0(15.0, 17.0)*§ 8.6(8.1, 9.2)* 9.3(8.5, 10.2)* 7.9(7.3, 8.7)*§ 6–11 Subtotal 5.5(5.1, 5.9) 6.0(5.4, 6.6) 5.2(4.6, 5.8) 1.3(1.1, 1.5) 1.5(1.3, 1.9) 1.1(0.8,1.4) Male 5.5(5.0, 6.1) 6.0(5.3, 6.8) 5.2(4.4, 6.1) 1.2(0.9, 1.5) 1.5(1.1, 2.0) 1.0(0.6, 1.5) Female 5.5(4.9, 6.2) 6.0(5.1, 7.0) 5.2(4.4, 6.1) 1.4(1.1, 1.7) 1.6(1.2, 2.2) 1.2(0.9, 1.6) 12–17 Subtotal 16.7(16.0, 17.4) 16.4(15.5, 17.4) 16.9(16.0, 17.9) 8.4(7.9, 8.9) 8.4(7.7, 9.1) 8.4(7.7, 9.2) Male 6.7(6.1, 7.4)† 6.6(5.7, 7.6) 6.9(6.0, 7.8)† 2.0(1.7, 2.4)† 2.0(1.6, 2.7) 2.0(1.6, 2.6)† Female 27.6(26.4, 28.8)*† 27.1(25.4, 28.8) *† 28.1(26.4, 29.8)*† 15.4(14.4, 16.4)*† 15.2(13.9, 16.7)*† 15.5(14.1, 17.0)*† Abbreviation: SF=serum ferritin.* Chi-squared test P-value <0.05 for differences between male and female at same age group;† Chi-squared test P-value <0.05 for differences between children 6–11 years and 12–17 years.§ Chi-squared test P-value <0.05 for differences between urban and rural areas.

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###### 通讯作者: 陈斌, bchen63@163.com
• 1.

沈阳化工大学材料科学与工程学院 沈阳 110142

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## Iron Status Among Children Aged 6−17 Years by Serum Ferritin — China, 2016−2017

View author affiliation

### Summary

What is already known on this topic?

Iron deficiency (ID) is the most widespread micronutrient deficiency and have several adverse effects on health. Consequences of ID among children include delayed psychomotor development and impaired cognitive performance, which makes it important to monitor the iron status of children.

What is added by this report?

In this study, the serum ferritin (SF) level was 56.6 (95% CI: 56.0–57.2) ng/mL in 65,293 children aged 6–17 years old in the National Nutrition and Health Surveillance in China in 2016–2017. ID prevalence varied significantly in children stratified by sex, age, and regions ranging from 1.0% to 28.1% judged by the standard of SF<15 ng/mL and SF<25 ng/mL. ID prevalence in females aged 12–17 years was the highest among children aged 6–17 years.

What are the implications for public health practice?

Understanding iron status of school children could provide evidence and data for developing policies and strategies for ID and iron deficiency anemia (IDA) control and prevention. Females aged 12–17 years showed high ID prevalence, and iron-rich food interventions are strongly recommended.

• 1. National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Key Laboratory of Trace Element Nutrition, National Health Commission of the People’s Republic of China, Beijing, China
###### doi: 10.46234/ccdcw2021.063
• Iron deficiency (ID) is the most prevalent micronutrient deficiency worldwide, resulting in adverse health outcomes including anemia, impaired muscle function, poor immune function, delayed psychomotor development, and impaired cognitive performance in children in the short and long term (1-2).

ID has three progressive stages which include depletion of iron stores (ID), iron deficient erythropoiesis (IDE), and iron deficiency anemia (IDA). Available indicators in different stages contain serum ferritin (SF), soluble transferrin receptor (sTfR), zinc protoporphyrin, transferrin saturation, body iron stores, hemoglobin, reticulocyte hemoglobin, and hepcidin, etc. Each indicator has their own strengths and limitations. SF is the most recommended indicator for determining ID because it reflects a state of iron store in the body and researchers have established a cutoff for iron depletion by using SF (3-4).

In 2015–2017, China completed its fifth National Nutrition and Health Surveillance and monitored the iron status with large-scale samples. The primary objective of this study was to analyze the prevalence of ID among children aged 6–17 years in China in 2016–2017 to provide guidance to the development of appropriate intervention strategies.

Sampling of participants was based on the protocol for China Nutrition and Health Surveillance of Children and Lactating Women (2016–2017). The details were described in the introduction of China Nutrition and Health Surveys (1982–2017) (5). The blood samples in the serum separator tube were promptly centrifuged at 3,000 ×g for 15 minutes after venous blood collection and coagulation at room temperature, divided into aliquots of serum, and frozen at –80 ℃ for subsequent assays: SF and high-sensitivity C-reactive protein (hsCRP). SF was measured by electrochemiluminescence immunoassay on Roche Modular e601 automated analyzer; and hsCRP by Roche Tina-quant immunoturbidimetric assay on Hitachi 7600 automatic biochemical analyzer.

All analyses were conducted with SPSS (version 23.0, IBM Corp, Armonk, NY, USA). We log transformed SF to normalize the distribution because SF concentrations were positively skewed. SF distribution was described as geometric means ($\overline x$G) and 95% confidence interval (95% CI) as well as selected percentiles by age and sex subgroups. Concentrations of hsCRP higher than 5 mg/L was considered as the presence of a possible infection or inflammation. ID was defined by the World Health Organization (WHO) recommended standard as SF<15 ng/mL and the National Hygienic Standard WS/T 465-2015 in China as SF<25 ng/mL; both standards were set in the absence of signs of inflammation (3,6). Independent t-tests and chi-squared tests were conducted on continuous variables and categorical variables between subgroups, respectively. Means, percentiles, ID prevalence, and differences between subgroups were analyzed from the method of complex sampling survey. The level of statistical significance was set at P<0.05.

In total, 65,293 participants were included after exclusion of hsCRP>5 mg/L, with 32,503 (50.0%) being male and 32,790 (50.0%) being female. The age of all children ranged from 6 to <18 years old with a median age of 11.3 years. The study population distribution was presented in Table 1.

 Age group (years) Total Urban Rural n $\bar{{{x}}}$G 95% CI n ${\bar{{x}}}$G 95% CI n $\bar{{{x}}}$G 95% CI 6–17 Total 65,293 56.6 56.0–57.2 30,960 57.9 57.0–58.8 34,333 55.5§ 54.7–56.2 Male 32,503 66.4 65.5–67.2 15,404 69.4 68.0–70.7 17,099 63.8§ 62.8–64.9 Female 32,790 47.3* 46.5–48.0 15,556 47.2* 46.1–48.4 17,234 47.3* 46.3–48.2 6–11 Subtotal 36,596 60.4 59.8–61.1 17,423 62.0 60.9–63.1 19,173 59.3§ 58.5–60.2 Male 18,223 60.5 59.6–61.5 8,665 62.2 60.7–63.8 9,558 59.3§ 58.1–60.6 Female 18,373 60.3 59.4–61.3 8,758 61.7 60.2–63.3 9,615 59.3§ 58.2–60.5 12–17 Subtotal 28,697 53.1 52.2–54.0 13,537 54.8 53.5–56.2 15,160 51.3§ 50.2–52.5 Male 14,280 72.7† 71.3–74.2 6,739 75.8† 73.7–78.1 7,541 69.6†§ 67.8–71.4 Female 14,417 37.6*† 36.7–38.6 6,798 38.5*† 37.2–40.0 7,619 36.7*b§ 35.5–37.9 Abbreviation: CI=Confidence Interval; $\overline x$G=geometric means. * P-value <0.05 for differences between male and female at same age group.† P-value <0.05 for differences between children 6–11 years and 12–17 years.§ P-value <0.05 for differences between urban and rural areas.

Table 1.  Serum ferritin levels for children aged 6–17 years — China, 2016–2017 (ng/mL).

As presented in Table 1, geometric mean SF concentrations were 57.9 (95% CI: 57.0–58.8) ng/mL and 55.5 (95% CI: 54.7–56.2) ng/mL for children aged 6–17 years in urban and rural areas, respectively. The SF concentrations were significantly higher in urban than those in rural areas, while males had a higher levels than that of females (P<0.05). The ferritin concentration in female subgroup aged 12–17 years was the lowest among all the subgroups (P<0.05).

Table 2 described the percentile distribution of SF concentrations in age and sex subgroups, which were widely arranged and varied among subgroups.

 Age group (years) P2.5 P5 P10 P25 P50 P75 P90 P95 P97.5 Total 6–17 Total 9.8 15.2 23.4 38.7 59.9 89.6 131.8 166.3 203.9 Male 17.9 23.1 30.3 45.0 66.5 100.3 147.7 188.3 225.7 Female 7.0 10.3 16.9 32.2 52.5 79.2 112.4 137.3 165.4 6–11 Subtotal 19.1 24.0 30.5 43.1 61.4 86.1 119.3 146.1 179.4 Male 19.3 24.1 30.5 43.3 61.2 84.9 119.7 148.2 187.8 Female 18.8 23.9 30.4 43.0 61.7 87.2 118.7 142.6 171.0 12–17 Subtotal 7.2 10.7 17.1 33.4 58.0 93.9 144.1 181.2 221.8 Male 16.7 21.8 30.1 47.6 75.1 118.2 171.5 212.7 251.8 Female 5.2 7.3 11.0 22.7 42.7 68.9 102.7 131.2 160.6 Urban 6–17 Total 9.2 14.5 22.5 38.3 61.4 95.5 141.0 181.0 220.7 Male 17.6 22.8 30.3 45.6 69.5 108.2 159.1 206.1 246.3 Female 6.5 9.7 15.6 31.2 52.7 81.4 118.6 146.2 177.8 6–11 Subtotal 18.2 23.4 30.0 43.3 63.1 90.8 125.9 158.7 197.5 Male 18.5 23.5 30.5 43.3 62.4 91.0 127.6 168.7 206.1 Female 17.8 23.3 29.6 43.2 63.6 90.8 125.0 153.3 189.1 12–17 Subtotal 7.0 10.7 17.2 33.7 59.6 100.1 152.3 193.5 236.1 Male 16.8 22.3 30.3 48.5 79.6 124.8 181.0 224.7 262.5 Female 5.2 7.1 11.2 22.9 43.5 71.4 111.6 142.0 170.4 Rural 6–17 Total 10.5 16.0 24.0 39.1 58.9 85.1 122.6 153.0 184.4 Male 18.1 23.4 30.3 44.4 64.3 93.1 138.3 172.9 205.2 Female 7.4 10.8 17.9 33.2 52.4 76.9 105.9 129.0 152.5 6–11 Subtotal 19.9 24.5 30.8 43.0 60.1 83.5 113.8 138.6 166.7 Male 20.1 24.5 30.5 43.3 60.1 81.9 114.4 140.5 168.9 Female 19.7 24.5 31.1 42.7 60.1 85.0 113.6 136.8 161.4 12–17 Subtotal 7.4 10.7 17.1 33.2 56.4 88.1 134.5 171.6 206.1 Male 16.3 21.4 29.8 46.7 71.6 109.6 161.1 198.4 231.6 Female 5.2 7.4 10.8 22.4 41.9 66.3 95.4 118.0 141.5

Table 2.  Median and selected percentiles of serum ferritin concentrations for children aged 6–17 years in China in 2016–2017 (ng/mL).

The prevalence of ID for children was shown in Table 3. Overall, the prevalence of ID in children aged 6–17 years, as defined by SF<25 ng/mL and SF<15 ng/mL, was 11.2% and 4.9% in this weighted population, respectively. According to ID judged by the cut-off value of 25 or 15 ng/mL for SF concentration, the prevalence of ID was significantly different in the subgroups by age, sex, or regions (P<0.05). Children aged 12–17 years had a higher incidence of ID than children aged 6–11 years (P<0.05). Males had a lower ID prevalence than females (P<0.05). The prevalence of ID in urban areas was significantly different with that in rural areas (P<0.05).

 Age group (years) SF<25 ng/mL SF<15 ng/mL Total Urban Rural Total Urban Rural 6–17 Total 11.2(10.8, 11.6) 11.8(11.2, 12.4) 10.6(10.1, 11.2)§ 4.9(4.6, 5.2) 5.4(4.9, 5.8) 4.5(4.1, 4.9)§ Male 6.1(5.7, 6.6) 6.3(5.7, 7.0) 5.9(5.4, 6.6) 1.6(1.4, 1.9) 1.8(1.5, 2.2) 1.4(1.2, 1.8) Female 16.9(16.2, 17.6)* 18.0(16.9, 19.0) * 16.0(15.0, 17.0)*§ 8.6(8.1, 9.2)* 9.3(8.5, 10.2)* 7.9(7.3, 8.7)*§ 6–11 Subtotal 5.5(5.1, 5.9) 6.0(5.4, 6.6) 5.2(4.6, 5.8) 1.3(1.1, 1.5) 1.5(1.3, 1.9) 1.1(0.8,1.4) Male 5.5(5.0, 6.1) 6.0(5.3, 6.8) 5.2(4.4, 6.1) 1.2(0.9, 1.5) 1.5(1.1, 2.0) 1.0(0.6, 1.5) Female 5.5(4.9, 6.2) 6.0(5.1, 7.0) 5.2(4.4, 6.1) 1.4(1.1, 1.7) 1.6(1.2, 2.2) 1.2(0.9, 1.6) 12–17 Subtotal 16.7(16.0, 17.4) 16.4(15.5, 17.4) 16.9(16.0, 17.9) 8.4(7.9, 8.9) 8.4(7.7, 9.1) 8.4(7.7, 9.2) Male 6.7(6.1, 7.4)† 6.6(5.7, 7.6) 6.9(6.0, 7.8)† 2.0(1.7, 2.4)† 2.0(1.6, 2.7) 2.0(1.6, 2.6)† Female 27.6(26.4, 28.8)*† 27.1(25.4, 28.8) *† 28.1(26.4, 29.8)*† 15.4(14.4, 16.4)*† 15.2(13.9, 16.7)*† 15.5(14.1, 17.0)*† Abbreviation: SF=serum ferritin.* Chi-squared test P-value <0.05 for differences between male and female at same age group;† Chi-squared test P-value <0.05 for differences between children 6–11 years and 12–17 years.§ Chi-squared test P-value <0.05 for differences between urban and rural areas.

Table 3.  Iron deficiency prevalence for children aged 6–17 years — China, 2016–2017 [% (95% CI)].

Reference (13)

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