Korean J Pediatr 2012;55(6):206-211 • http://dx.doi.org/10.3345/kjp.2012.55.6.206 211 exclusive breast-feeding and maternal anemia in a Mexican cohort. J Nutr 2006;136:452-8. High-dose alfacalcidol improves anaemia in patients on haemodialysis. Nephrol Dial Transplant 1997;12:514-8. 22. Statistics Korea, Korean Statistical Information Service [Internet]. Daejeon: Statistics Korea; c1996 [cited 2011 Mar 20]. Available from: http://kosis.kr. 23. Cook JD, Lipschitz DA, Miles LE, Finch CA. Serum ferritin as a measure of iron stores in normal subjects. Am J Clin Nutr 1974;27:681-7. 24. Greer FR. Defining vitamin D deficiency in children: beyond 25-OH vitamin D serum concentrations. Pediatrics 2009;124:1471-3. 25. Holick MF. Vitamin D status: measurement, interpretation, and clinical application. Ann Epidemiol 2009;19:73-8. 26. Holick MF. High prevalence of vitamin D inadequacy and implications for health. Mayo Clin Proc 2006;81:353-73. 27. Cole CR, Grant FK, Tangpricha V, Swaby-Ellis ED, Smith JL, Jacques A, et al. 25-hydroxyvitamin D status of healthy, low-income, minority children in Atlanta, Georgia. Pediatrics 2010;125:633-9. 28. Sim JJ, Lac PT, Liu IL, Meguerditchian SO, Kumar VA, Kujubu DA, et al. Vitamin D deficiency and anemia: a cross-sectional study. Ann Hematol 2010;89:447-52. 29. Albitar S, Genin R, Fen-Chong M, Serveaux MO, Schohn D, Chuet C. 30. Saab G, Young DO, Gincherman Y, Giles K, Norwood K, Coyne DW. Prevalence of vitamin D deficiency and the safety and effectiveness of monthly ergocalciferol in hemodialysis patients. Nephron Clin Pract 2007;105:c132-8. 31. Reichel H, Koeffler HP, Norman AW. The role of the vitamin D endo- crine system in health and disease. N Engl J Med 1989;320:980-91. 32. Ward LM, Gaboury I, Ladhani M, Zlotkin S. Vitamin D-deficiency rickets among children in Canada. CMAJ 2007;177:161-6. 33. Wagner CL, Greer FR; American Academy of Pediatrics Section on Breastfeeding; American Academy of Pediatrics Committee on Nutrition. Prevention of rickets and vitamin D deficiency in infants, children, and adolescents. Pediatrics 2008;122:1142-52. 34. Bondevik GT, Lie RT, Ulstein M, Kvale G. Seasonal variation in risk of anemia among pregnant Nepali women. Int J Gynaecol Obstet 2000; 69:215-22. 35. Jiang T, Christian P, Khatry SK, Wu L, West KP Jr. Micronutrient defi- ciencies in early pregnancy are common, concurrent, and vary by season among rural Nepali pregnant women. J Nutr 2005;135:1106-12.