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Purpose: Previous studies have revealed many inconsistent results regarding the relationship between vitamin D and metabolic syndrome. The purpose of our study was to investigate the association between serum 25-hydroxyvitamin D (25(OH)D) concentration and factors that characterize metabolic syndrome in Korean children and adolescents. Methods: We analyzed data from 2,880 children and adolescents aged 10-18 years collected from the 2008-2010 Korean National Health and Nutrition Examination Survey. We investigated the data according to quartiles of 25(OH)D concentrations. Results: Systolic blood pressure and diastolic blood pressure with adjustment for sex and age differed significantly between the serum 25(OH)D groups and exhibited negative trend as 25(OH)D concentrations increased. The number of subjects with metabolic syndrome was greater in the low 25(OH)D groups (I, II, and III quartile) than in the high 25(OH)D group (IV quartile) (P=0.029). BMI and waist circumference were lower in the high 25(OH)D group. Serum 25(OH)D concentration correlated negatively with homeostasis model assessment estimate of insulin resistance (ρ=- 0.073, P<0.001) and correlated positively with quantitative insulin sensitivity check index (ρ=0.095, P<0.001). Conclusion: Low serum 25(OH)D level is associated with an increase of insulin resistance and metabolic syndrome in children and adolescents. [ABSTRACT FROM AUTHOR]

Purpose: Short stature is a very common reason for visits to pediatric endocrine clinics. It could be the irst sign of an underlying disease. The purpose of this study is to investigate the etiologies and general characteristics of subjects who visited an outpatient clinic due to short stature. Methods: We retrospectively reviewed the medical records of 3,371 patients who visited Severance Children's Hospital with the chief complaint of short stature from 2010 to 2012. Medical history, auxological data, and laboratory tests including bone age were collected and analyzed. Chromosome studies or combined pituitary function tests were performed if needed. Results: Approximately 89.4% of the subjects with the chief complaint of short stature who visited the outpatient clinic were of normal height, and only 10.6% of subjects were identiied as having short stature. Of the subject of short stature, 44.7% were classiied as having normal variant short stature; that is, familial short stature (23.0%), constitutional delay in growth (17.7%), and mixed form (3.9%). Pathological short stature was found in 193 subjects (54.2%). Among pathological short stature, most common etiology was growth hormone deficiency (GHD) (38.9%). Conclusion: A majority of children had a normal height. Among children with short stature, pathological short stature and normal variants occupied a similar percentage. GHD was the most common cause of pathological short stature and found in about 20% of the children with short stature. In pathological short stature, the height, height velocity, and IGF-1 level were lower than in normal variants. [ABSTRACT FROM AUTHOR]

Purpose: The rapid increase in the incidence of precocious puberty in Korea has clinical and social significance. Gonadotropin-releasing hormone (GnRH) stimulation test is required to diagnose central precocious puberty (CPP), however this test is expensive and time-consuming. This study aimed to identify factors that can predict a positive response to the GnRH stimulation test. Methods: Clinical and laboratory parameters, including basal serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), and estradiol (E2), were measured in 540 girls with clinical signs of CPP . Results: Two hundred twenty-nine of 540 girls with suspected CPP had a peak serum LH level higher than 5 IU/L (the CPP group). The CPP group had advanced bone age (P<0.001), accelerated yearly growth rate (P<0.001), increased basal levels of LH (P=0.02), FSH (P<0.001), E2 (P=0.001), and insulin-like growth factor-I levels (P<0.001) compared to the non-CPP group. In contrast, body weight (P<0.001) and body mass index (P<0.001) were lower in the CPP group. Although basal LH was significantly elevated in the CPP group compared to the non-CPP group, there was considerable overlap between the 2 groups. Cutoff values of basal LH (0.22 IU/L) detected CPP with 87.8% sensitivity and 20.9% specificity. Conclusion: No single parameter can predict a positive response on the GnRH stimulation test with both high sensitivity and specificity. Therefore, multiple factors should be considered in evaluation of sexual precocity when deciding the timing of the GnRH stimulation test. [ABSTRACT FROM AUTHOR]