208 JW Yoon, et al. • Vitamin D deficiency and iron deficiency anemia was 17.3±1.8 kg/m2. One fourth of the patients had preterm birth and 24% of subjects had maternal anemia, but only 15 patients (19%) took vitamin-mineral supplements. More than half of the patients were hospitalized for diseases such as pneumonia, bronchiolitis, or gastroenteritis. We compared the etiology of IDA according to patient age. The prevalence of breast feeding was 93% in children younger than 2 years, and was 64% in children older than 2 years (P<0.05) (Table 2). Two patients older than 2 years ingested cow's milk over 1,000 mL per day and one patient with chronic gastro-intestinal bleeding was identified as having abdominal lymphangioma. Our measurement of vitamin D status indicated that 46 subjects (58%) had plasma 25OHD below 30 ng/mL, and that 31 of these subjects (39%) had VDD (25OHD<20 ng/mL). A total of 30 subjects (44%) younger than 2 years had VDD, but only 1 child older than 2 years (9%) had VDD (P =0.028). Twelve patients (15%) had elevated ALP and 5 patients (6%) had radiologic evidence of rickets, and all of these patients were younger than 2 years (P =0.159 andP =0.392, respectively). Except one patient, none of them had clinical signs of rickets. An 8 month-old patient who presented with hypocalcemic seizure at diagnosis had low levels of serum 25OHD and calcium but, did not have more severe IDA than the asymptomatic subjects. Subjects with radiologic evidence of rickets had lower levels of serum 25OHD, lower levels of phosphorus, and higher levels of serum ALP level than those with no evidence of rickets (P =0.04,P<0.001, andP<0.001, respectively). However, IDA parameters were similar between these two groups. Univariate analysis indicated that VDD was significantly asso- ciated with younger age, breastfeeding, phosphorus and ALP but Table 2. Feeding Pattern, Vitamin D and Alkaline Phosphatase Status, and Radiological Evidence of Rickets in Children with Iron Deficiency Anemia Characteristic Total (n=79) Age<2 yr (n=68) Age≥2 yr (n=11) Feeding pattern Breast milk only 70 (89) 63 (93) 7 (64)† Breast milk and formula 7 (9) 5 (7) 2 (18) Formula only 2 (2) 0 (0) 2 (18) 25OHD sufficiency 33 (42) 27 (40) 6 (55) 25OHD insufficiency 15 (19) 11 (16) 4 (36) 25OHD deficiency 31 (39) 30 (44) 1 (9)† Elevated ALP* 12 (15) 12 (17) 0 (0) Radiologic evidence of rickets 5 (6) 5 (7) 0 (0) Values are presented as number (%). 25OHD, 25-hydroxyvitamin D; ALP, alkaline phosphatase. *ALP >1,000 IU/L. †P <0.05 vs. patients younger than 2yr; 25OHD sufficiency, ≥30 ng/mL; 25OHD insufficiency, between 20 and 30 ng/mL; 25OHD deficiency, <20 ng/mL not with gender, birth weight, preterm birth, radiologic evidence of rickets, serum calcium, or IDA variables (Hb, MCV, RDW, reticulocytes, ferritin, iron, and TIBC) (Table 3). We also analyzed the numbers of patients who were vitamin D sufficient, insufficient, and deficient, and the levels of vitamin D according to season (Fig. 1). The number of patients with VDI was 26 (76%) in spring (March to May), 12 (67%) in winter (December to February), 6 (33%) in summer (June to August), and 1 (22%) in autumn (September to November) (P <0.001). The mean level of serum 25OHD was significantly lower in spring/winter than summer/autumn (24±20 vs. 47±26 mg/dL,P <0.001). The spring season had the highest rate of VDD (56%). Serum Hb and ferritin concentrations were higher in winter than summer and autumn, and RDW levels were lowest in winter, but these differences were not significant (data not shown). By multivariable logistic regression the only independent risk factor for VDD was 25OHD tested in the winter or spring (odds ratio, 5.7; 95% CI, 1.7 to 19.3). Other variables including age and breastfeeding which were significant in the univariate analysis were not independently associated with VDD (Table 4). Discussion In this study, 58% of the IDA children had subnormal vitamin D level and 39% had VDD. A total of 89% of the children were Table 3. Characteristics of Iron Deficiency Anemia Children, Stratified by Vitamin D Status 25OHD 25OHD Characteristic ≥20 ng/mL <20 ng/mL P value (n=48) (n=31) Age (mo) 28.7±44.0 11.0±5.7 0.008 Female sex 16 (33) 8 (26) NS Birth weight (kg) 2.9±0.5 3.0±0.6 NS Preterm birth 10 (21) 11 (35) NS Breast feeding 40 (83) 30 (97) 0.093 Radiologic evidence of rickets 1 (2) 4 (13) NS 25OHD (ng/mL) 46.9±21.2 9.9±6.2 Calcium (mg/dL) 9.6±0.6 9.7±1.0 NS Phosphorus (mg/dL) 5.1±0.8 4.7±1.0 0.048 ALP (IU/L) 607±284 837±560 0.045 Hemoglobin (g/dL) 8.8±1.6 9.2±1.3 NS Ferritin (ng/mL) 8.3±8.9 15.7±27.6 NS Iron (µg/dL) 14.4±11.8 15.5±10.2 NS TIBC (µg/dL) 418±63 396±65 NS Values are presented as mean±SD or number (%). 25OHD, 25-hydroxyvitamin D; ALP, alkaline phosphatase; TIBC, total iron- binding capacity; NS, non-specific.