To construct new Korean reference curves for birth weight by sex and gestational age using contemporary Korean birth weight data and to compare them with the Lubchenco and the 2010 United States (US) intrauterine growth curves. Data of 2,336,727 newborns by the Korean Statistical Information Service (2008-2012) were used. Smoothed percentile curves were created by the Lambda Mu Sigma method using subsample of singleton. The new Korean reference curves were compared with the Lubchenco and the 2010 US intrauterine growth curves. Reference of the 3rd, 10th, 25th, 50th, 75th, 90th, and 97th percentiles birth weight by gestational age were made using 2,249,804 (male, 1,159,070) singleton newborns with gestational age 23-43 weeks. Separate birth weight curves were constructed for male and female. The Korean reference curves are similar to the 2010 US intrauterine growth curves. However, the cutoff values for small for gestational age (<10th percentile) of the new Korean curves differed from those of the Lubchenco curves for each gestational age. The Lubchenco curves underestimated the percentage of infants who were born small for gestational age. The new Korean reference curves for birth weight show a different pattern from the Lubchenco curves, which were made from white neonates more than 60 years ago. Further research on short-term and long-term health outcomes of small for gestational age babies based on the new Korean reference data is needed.

To analyze predictive factors suggesting transient congenital hypothyroidism (TCH) compared to permanent congenital hypothyroidism (PCH) or transient thyroid function test (TFT) abnormalities among children who had positive screening results at our centers over the past decade. A retrospective chart review of 105 subjects who presented elevated TSH levels on a newborn screening test (NST) was done. TCH was defined when a trial-off therapy was successful, and PCH was defined when a trial failed or when the subject was kept on medication beyond 3 years of age. A transient TFT abnormality was defined when follow-up TFTs were normalized without levothyroxine (LT4) therapy. Congenital hypothyroidism (CH) was diagnosed in 75.2% (TCH 35.2% and PCH 40.0%) of all subjects; the others (24.8%) showed transient TFT abnormalities. Initial NST-TSH levels (optimal cutoff point, 31.0 μIU/mL), the LT4 dose at 2 years of age (4.1 μg/kg/day), and the maximal LT4 dose (50 μg/day) merged as significant predictive factors discriminating between TCH and PCH. The initial serum level of free T4 (1.06 ng/dL) and not TSH (27.2 μIU/mL) was the only discriminating factor between transient TFT abnormalities and TCH. Earlier re-evaluation might be possible when a patient's initial NST-TSH levels and maximal or 2-year LT4 doses are low, as both are important predictors of successful trial-off therapy in CH patients. When the initial serum level of free T4 is above the average value in neonates with mildly elevated TSH levels, TFTs may be more likely to normalize on their own.

Cholesterol levels vary throughout childhood and adolescence. The aim of the present study was to evaluate and identify age- and gender-specific reference values for serum lipid concentrations including non-high-density lipoprotein cholesterol (non-HDL-C) and the triglyceride to HDL-C ratio (TG/HDL-C ratio) in apparently healthy Korean children and adolescents. A total of 6197 participants aged 10 to 19 years old from the 2007-2013 Korean National Health and Nutrition Examination Survey were analyzed. Serum lipid concentrations were evaluated according to age and gender. The overall mean concentration of non-HDL-C was 105.5±25.6 mg/dL, with a significant gender difference: 103.3±26.1 mg/dL in boys and 107.9±24.7 mg/dL in girls (p=0.028). The median values of non-HDL-C concentrations in boys and girls, respectively, were 111 and 112 mg/dL in the 10-year-old age group, 95 and 103 mg/dL in the 15-year-old age group, and 109 and 103 mg/dL in the 19-year-old age group. The overall mean TG/HDL-C ratio was 1.74±1.22, and there were no significant gender differences: 1.77±1.25 in boys and 1.72±1.22 in girls (p=0.183). The median values of the TG/HDL-C ratio in boys and girls were 1.16 and 1.00 in the 10-year-olds, 1.54 and 0.95 in the 15-year-olds, and 1.74 and 0.84 in the 19-year-olds, respectively. Age- and gender-specific reference values for non-HDL-C and for the TG/HDL-C ratio in children and adolescents could provide valuable information for individualized interpretations of lipid profiles and interventions as well as for strategies to prevent and manage childhood and adolescent dyslipidemia.

The Committee on Dyslipidemia of Korean Pediatric and Adolescents of the Korean Society of Pediatric Endocrinology has newly developed evidence-based clinical practice guidelines for dyslipidemia in Korean children and adolescents. These guidelines were formulated with the Grading of Recommendations, which include both the strength of recommendations and the quality of evidence. In the absence of sufficient evidence, conclusions were based on expert opinion. These guidelines are based on the 2011 National Heart, Lung, and Blood Institute Guidelines, which focus on the prevention of cardiovascular disease in children and draw from a comprehensive review of evidence. These guidelines contain the definition of and screening process for dyslipidemia and introduce new dietary methods: the Cardiovascular Health Integrated Lifestyle Diet (CHILD)-1, the CHILD-2-low-density lipoprotein cholesterol, and the CHILD-2-triglyceride. Potential drug therapies for dyslipidemia along with their main effects and doses were also included.

Children born small for gestational age (SGA) face an increased risk of health problems in later life, particularly persistent short stature, neurocognitive dysfunction, impaired renal and pulmonary function, decreased bone density, sensorineural hearing loss, premature adrenarche, and metabolic syndrome. Insulin resistance appears to be a key component underlying these metabolic complications. Long-term, continuous, GH treatments in short children born SGA lead to a normalization of height through childhood to adulthood. Recombinant human GH has been proven to be relatively safe. We recommend early surveillance in a growth clinic for children born SGA without catch-up growth. Obesity, insulin resistance, and the risk of metabolic syndrome increase with catch-up growth, but short stature and cognitive dysfunction increase without catch-up growth in children born SGA. A solution to this catch-up dilemma is breast feeding for a minimum of 6 to 12 mo. Because the overall prevalence of metabolic risk factors is very low, routine evaluation of metabolic parameters is not recommended for all children born SGA, but it may be useful to consider metabolic evaluations in overweight or obese children born SGA. Since children born SGA have many risk factors, long-term management from neonate to adulthood is very important.

In the pediatric population, Rathke's cleft cysts (RCCs) are known to be an infrequent cause of headaches, visual disturbances, and pituitary dysfunction. We investigated the clinical characteristics of children in whom RCCs were incidentally discovered and evaluated whether RCCs influence the treatment response of patients with proven endocrinopathy. A retrospective analysis was conducted in 34 patients with RCCs who were diagnosed between 2006 and 2013 at Hallym University Medical Center. Their clinical, hormonal, and imaging findings were reviewed. We evaluated the clinical outcomes of the patients with concomitant RCCs and endocrinopathy compared to matched controls. Twenty-six of 34 patients with radiologically proven RCCs had endocrine disorders. They were 9 boys and 17 girls, with ages ranging from 4.8 to 17.4 years at the time of the diagnosis. Of these, 7 (27%) had idiopathic short stature, 7 (27%) had growth hormone deficiency (GHD), and 12 (46%) had central precocious puberty (CPP). Nineteen of 26 patients (73.1%) showed low signal intensities on T1-weighted images (T1WI) and high signal intensities on T2-weighted images. The incidence of hypointensity on T1WI was higher in the patients with RCCs accompanied by endocrinopathy than in those without endocrinopathy (P=0.033). The treatment outcomes of the patients with CPP and GHD with and without RCCs were similar. CPP and GHD patients with a small RCC (less than 20 mm) expressing cystic magnetic resonance intensity can be managed with medical treatment, although the RCCs need to be closely monitored in radiological studies to observe their growth.