Recent studies suggest that vitamin D insufficiency or deficiency is not only a problem of older generations anymore but also an important health concern among younger generations. However, comprehensive data are lacking in Korean adolescents. We investigated the vitamin D (25-hydroxy vitamin D [25(OH)D]) status, the prevalence of vitamin D insufficiency or deficiency, and the association between vitamin D levels and insulin resistance and lipid profiles in a sample of 188 Korean adolescents aged 12-13 years who participated in a general health check-up at a tertiary hospital. Vitamin D deficiency was considered as serum concentrations <20 ng/mL (50 nmol/L); a level of 21-29 ng/mL (52-72 nmol/L) was considered to indicate vitamin D insufficiency, whereas a level of 30 ng/mL or greater (>75 nmol/L) was considered sufficient or optimum. In this cross-sectional study, vitamin D insufficiency or deficiency was found in 98.9 % of boys and 100 % of girls, whereas only 1.1 % of boys and 0 % of girls had a serum 25(OH)D level of greater than 30 ng/mL. In multivariate linear regression analysis, HOMA-IR, triglyceride, and LDL cholesterol were inversely associated with 25(OH)D concentrations. We found that vitamin D insufficiency or deficiency is a very common health problem in Korean adolescents, particularly in girls, and that serum 25(OH)D levels are inversely associated with insulin resistance and lipid profiles. These results suggest that more time spent in outdoor activity for sunlight exposure and higher vitamin D intake may be needed in younger adolescents in South Korea.

PurposeBronchopulmonary dysplasia (BPD) is characterized by inflammation with proteolytic damage to the lung extracellular matrix. The results from previous studies are inconsistent regarding the role of proteinases and antiproteinases in the development of BPD. The aim of the present study was to investigate whether matrix metalloproteinase (MMP)-8, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-2, and TIMP-1 levels in the serum of preterm infants at birth are related to the development of BPD.MethodsSerum was collected from 62 preterm infants at birth and analyzed for MMP-8, MMP-9, TIMP-2, and TIMP-1 by using enzyme-linked immunosorbent assay. MMPs and TIMPs were compared in BPD (n=24) and no BPD groups (n=38). Clinical predictors of BPD (sex, birth weight, gestational age, etc.) were assessed for both groups. The association between predictors and outcome, BPD, was assessed by using multivariate logistic regression.ResultsSex, birth weight, and mean gestational age were similar between the groups. BPD preterm infants had significantly lower TIMP-2 levels at birth compared with no BPD preterm infants (138.1±23.0 ng/mL vs. 171.8±44.1 ng/mL, P=0.027). No significant difference was observed in MMP-8, MMP-9, and TIMP-1 levels between the two groups. Multivariate logistic regression analysis indicated that the TIMP-2 levels were predictive of BPD after adjusting for sex, birth weight, gestational age, proteinuric preeclampsia, and intraventricular hemorrhage (β=-0.063, P=0.041).ConclusionLow TIMP-2 serum levels at birth may be associated with the subsequent development of BPD in preterm infants.