Purpose: Congenital hypothyroidism (CH) is a major preventable cause of intellectual disability, particularly in very low birth weight (VLBW) infants, who are at increased risk due to hypothalamic-pituitary-thyroid axis immaturity. Early differentiation between transient CH (TCH) and permanent CH (PCH) is crucial to optimize L-thyroxine (LT4) treatment duration. This study aimed to determine the incidence of PCH among Korean VLBW infants and to identify clinical factors that may aid in distinguishing TCH from PCH. Methods: This retrospective cohort study included VLBW infants diagnosed with CH and treated with LT4 at a single tertiary neonatal intensive care unit between 2011 and 2020. Infants requiring LT4 beyond 3 years were classified as PCH, while those who discontinued earlier were considered TCH. Clinical characteristics, neonatal morbidities, and thyroid-related parameters were compared between the groups. Results: Among 1,292 VLBW infants, 122 (9.4%) were diagnosed with CH. After excluding deaths and those lost to follow-up, 73 infants were included in the final analysis (TCH, n=50; PCH, n=23). The PCH group had a significantly higher mean gestational age and greater LT4 requirements at both 12 and 36 months of age. Major anomalies were more frequently observed in PCH infants, including congenital heart defects. In multivariate analysis, higher gestational age, the presence of major anomalies, screening thyroid-stimulating hormone (TSH) >10 μIU/mL, and higher LT4 dose at 36 months were significantly associated with PCH. Conclusion The incidence of PCH in Korean VLBW infants was relatively higher than that reported in previous studies studies. Screening TSH level and LT4 dose requirements may support individualized follow-up and help distinguish PCH from TCH.

Purpose: Congenital hypothyroidism (CH) is a major preventable cause of intellectual disability, particularly in very low birth weight (VLBW) infants, who are at increased risk due to hypothalamic-pituitary-thyroid axis immaturity. Early differentiation between transient CH (TCH) and permanent CH (PCH) is crucial to optimize L-thyroxine (LT4) treatment duration. This study aimed to determine the incidence of PCH among Korean VLBW infants and to identify clinical factors that may aid in distinguishing TCH from PCH. Methods: This retrospective cohort study included VLBW infants diagnosed with CH and treated with LT4 at a single tertiary neonatal intensive care unit between 2011 and 2020. Infants requiring LT4 beyond 3 years were classified as PCH, while those who discontinued earlier were considered TCH. Clinical characteristics, neonatal morbidities, and thyroid-related parameters were compared between the groups. Results: Among 1,292 VLBW infants, 122 (9.4%) were diagnosed with CH. After excluding deaths and those lost to follow-up, 73 infants were included in the final analysis (TCH, n=50; PCH, n=23). The PCH group had a significantly higher mean gestational age and greater LT4 requirements at both 12 and 36 months of age. Major anomalies were more frequently observed in PCH infants, including congenital heart defects. In multivariate analysis, higher gestational age, the presence of major anomalies, screening thyroid-stimulating hormone (TSH) >10 μIU/mL, and higher LT4 dose at 36 months were significantly associated with PCH. Conclusion The incidence of PCH in Korean VLBW infants was relatively higher than that reported in previous studies studies. Screening TSH level and LT4 dose requirements may support individualized follow-up and help distinguish PCH from TCH.

Purpose: 46,XX disorders of sex development (DSD) involve atypical genitalia accompanied by a normal female karyotype. This study was performed to investigate the clinical characteristics and long-term outcomes of patients with 46,XX DSD. Methods: The study included 34 patients with 46,XX DSD who presented with ambiguous genitalia or delayed puberty. Patients with congenital adrenal hyperplasia were excluded. Clinical phenotypes and overall outcomes were analyzed retrospectively. Results: Age at presentation ranged from birth to 40 years (median, 0.6 years), and the follow-up period ranged from 0.3 to 29.7 years (median, 8.8 years). Twenty patients were assigned female (58.8%). Etiologies included disorders of gonadal development (n=22), exogenous androgen exposure during pregnancy (n=5), association with syndromic disorders or genital anomalies (n=2), and unclassified causes (n=5). Ovotestis was the most frequent gonadal pathology (41.7%). Müllerian duct remnants were usually underdeveloped (52.9%) or absent (23.5%). Spontaneous puberty occurred in 17 of the 21 patients of pubertal age, while 9 patients required sex hormone replacement therapy. Gonadal complications were observed in 4 patients (gonadal tumors [n=3], and spontaneous gonadal rupture [n=1]), and gender dysphoria occurred in 1 patient who was assigned male. Conclusion This study described the wide phenotypic spectrum and pubertal outcome of patients with 46,XX DSD. Long-term multidisciplinary monitoring for pubertal development, fertility, gender identity, and gonadal complications is recommended.

Purpose: Congenital hypothyroidism (CH) is a major preventable cause of intellectual disability, particularly in very low birth weight (VLBW) infants, who are at increased risk due to hypothalamic-pituitary-thyroid axis immaturity. Early differentiation between transient CH (TCH) and permanent CH (PCH) is crucial to optimize L-thyroxine (LT4) treatment duration. This study aimed to determine the incidence of PCH among Korean VLBW infants and to identify clinical factors that may aid in distinguishing TCH from PCH. Methods: This retrospective cohort study included VLBW infants diagnosed with CH and treated with LT4 at a single tertiary neonatal intensive care unit between 2011 and 2020. Infants requiring LT4 beyond 3 years were classified as PCH, while those who discontinued earlier were considered TCH. Clinical characteristics, neonatal morbidities, and thyroid-related parameters were compared between the groups. Results: Among 1,292 VLBW infants, 122 (9.4%) were diagnosed with CH. After excluding deaths and those lost to follow-up, 73 infants were included in the final analysis (TCH, n=50; PCH, n=23). The PCH group had a significantly higher mean gestational age and greater LT4 requirements at both 12 and 36 months of age. Major anomalies were more frequently observed in PCH infants, including congenital heart defects. In multivariate analysis, higher gestational age, the presence of major anomalies, screening thyroid-stimulating hormone (TSH) >10 μIU/mL, and higher LT4 dose at 36 months were significantly associated with PCH. Conclusion The incidence of PCH in Korean VLBW infants was relatively higher than that reported in previous studies studies. Screening TSH level and LT4 dose requirements may support individualized follow-up and help distinguish PCH from TCH.

Purpose: 46,XX disorders of sex development (DSD) involve atypical genitalia accompanied by a normal female karyotype. This study was performed to investigate the clinical characteristics and long-term outcomes of patients with 46,XX DSD. Methods: The study included 34 patients with 46,XX DSD who presented with ambiguous genitalia or delayed puberty. Patients with congenital adrenal hyperplasia were excluded. Clinical phenotypes and overall outcomes were analyzed retrospectively. Results: Age at presentation ranged from birth to 40 years (median, 0.6 years), and the follow-up period ranged from 0.3 to 29.7 years (median, 8.8 years). Twenty patients were assigned female (58.8%). Etiologies included disorders of gonadal development (n=22), exogenous androgen exposure during pregnancy (n=5), association with syndromic disorders or genital anomalies (n=2), and unclassified causes (n=5). Ovotestis was the most frequent gonadal pathology (41.7%). Müllerian duct remnants were usually underdeveloped (52.9%) or absent (23.5%). Spontaneous puberty occurred in 17 of the 21 patients of pubertal age, while 9 patients required sex hormone replacement therapy. Gonadal complications were observed in 4 patients (gonadal tumors [n=3], and spontaneous gonadal rupture [n=1]), and gender dysphoria occurred in 1 patient who was assigned male. Conclusion This study described the wide phenotypic spectrum and pubertal outcome of patients with 46,XX DSD. Long-term multidisciplinary monitoring for pubertal development, fertility, gender identity, and gonadal complications is recommended.

Purpose: Congenital hypothyroidism (CH) is a major preventable cause of intellectual disability, particularly in very low birth weight (VLBW) infants, who are at increased risk due to hypothalamic-pituitary-thyroid axis immaturity. Early differentiation between transient CH (TCH) and permanent CH (PCH) is crucial to optimize L-thyroxine (LT4) treatment duration. This study aimed to determine the incidence of PCH among Korean VLBW infants and to identify clinical factors that may aid in distinguishing TCH from PCH. Methods: This retrospective cohort study included VLBW infants diagnosed with CH and treated with LT4 at a single tertiary neonatal intensive care unit between 2011 and 2020. Infants requiring LT4 beyond 3 years were classified as PCH, while those who discontinued earlier were considered TCH. Clinical characteristics, neonatal morbidities, and thyroid-related parameters were compared between the groups. Results: Among 1,292 VLBW infants, 122 (9.4%) were diagnosed with CH. After excluding deaths and those lost to follow-up, 73 infants were included in the final analysis (TCH, n=50; PCH, n=23). The PCH group had a significantly higher mean gestational age and greater LT4 requirements at both 12 and 36 months of age. Major anomalies were more frequently observed in PCH infants, including congenital heart defects. In multivariate analysis, higher gestational age, the presence of major anomalies, screening thyroid-stimulating hormone (TSH) >10 μIU/mL, and higher LT4 dose at 36 months were significantly associated with PCH. Conclusion The incidence of PCH in Korean VLBW infants was relatively higher than that reported in previous studies studies. Screening TSH level and LT4 dose requirements may support individualized follow-up and help distinguish PCH from TCH.

Purpose: 46,XX disorders of sex development (DSD) involve atypical genitalia accompanied by a normal female karyotype. This study was performed to investigate the clinical characteristics and long-term outcomes of patients with 46,XX DSD. Methods: The study included 34 patients with 46,XX DSD who presented with ambiguous genitalia or delayed puberty. Patients with congenital adrenal hyperplasia were excluded. Clinical phenotypes and overall outcomes were analyzed retrospectively. Results: Age at presentation ranged from birth to 40 years (median, 0.6 years), and the follow-up period ranged from 0.3 to 29.7 years (median, 8.8 years). Twenty patients were assigned female (58.8%). Etiologies included disorders of gonadal development (n=22), exogenous androgen exposure during pregnancy (n=5), association with syndromic disorders or genital anomalies (n=2), and unclassified causes (n=5). Ovotestis was the most frequent gonadal pathology (41.7%). Müllerian duct remnants were usually underdeveloped (52.9%) or absent (23.5%). Spontaneous puberty occurred in 17 of the 21 patients of pubertal age, while 9 patients required sex hormone replacement therapy. Gonadal complications were observed in 4 patients (gonadal tumors [n=3], and spontaneous gonadal rupture [n=1]), and gender dysphoria occurred in 1 patient who was assigned male. Conclusion This study described the wide phenotypic spectrum and pubertal outcome of patients with 46,XX DSD. Long-term multidisciplinary monitoring for pubertal development, fertility, gender identity, and gonadal complications is recommended.

Purpose: Congenital hypothyroidism (CH) is a major preventable cause of intellectual disability, particularly in very low birth weight (VLBW) infants, who are at increased risk due to hypothalamic-pituitary-thyroid axis immaturity. Early differentiation between transient CH (TCH) and permanent CH (PCH) is crucial to optimize L-thyroxine (LT4) treatment duration. This study aimed to determine the incidence of PCH among Korean VLBW infants and to identify clinical factors that may aid in distinguishing TCH from PCH. Methods: This retrospective cohort study included VLBW infants diagnosed with CH and treated with LT4 at a single tertiary neonatal intensive care unit between 2011 and 2020. Infants requiring LT4 beyond 3 years were classified as PCH, while those who discontinued earlier were considered TCH. Clinical characteristics, neonatal morbidities, and thyroid-related parameters were compared between the groups. Results: Among 1,292 VLBW infants, 122 (9.4%) were diagnosed with CH. After excluding deaths and those lost to follow-up, 73 infants were included in the final analysis (TCH, n=50; PCH, n=23). The PCH group had a significantly higher mean gestational age and greater LT4 requirements at both 12 and 36 months of age. Major anomalies were more frequently observed in PCH infants, including congenital heart defects. In multivariate analysis, higher gestational age, the presence of major anomalies, screening thyroid-stimulating hormone (TSH) >10 μIU/mL, and higher LT4 dose at 36 months were significantly associated with PCH. Conclusion The incidence of PCH in Korean VLBW infants was relatively higher than that reported in previous studies studies. Screening TSH level and LT4 dose requirements may support individualized follow-up and help distinguish PCH from TCH.

Purpose: We aimed to identify the genetic causes of hypospadias in children using targeted gene panel sequencing for disorders of sex development (DSD). Materials and Methods: This study included 18 twin boys with hypospadias: seven and two pairs were monozygotic and dizygotic twins, respectively, and six were discordant and three were concordant twins. Targeted gene panel sequencing for 67 known DSD genes was performed. Sequence variants were classified into five different categories, pathogenic, likely pathogenic, variants of uncertain significance, likely benign, and benign, following the American College of Medical Genetics and Genomics Standards and Guidelines. Results: The mean gestational age and birth weight were 35.3±2.0 weeks and 1.96±0.61 kg, respectively, with seven patients being small for gestational age. Hypospadias was present in 12 patients, with posterior type in 33.3% and anterior type in 66.7%.In three families with twins, both siblings had hypospadias. In addition, cryptorchidism was observed in one subject. Surgical correction of hypospadias was performed at a mean age of 22.1 months. Molecular analysis identified 12 different genetic variants, including two pathogenic mutations in the AMH (p.E389*) and SRD5A2 (p.R246Q) genes, found in subjects with hypospadias, respectively. However, only heterozygous mutations were detected. Conclusions This study did not identify a definitive genetic component contributing to the development of hypospadias; however, the findings suggest that intrauterine growth retardation may play a significant role.

Purpose: As the survival rate from pediatric cancers has increased significantly with advances in treatment modalities, long-term endocrine complications have also risen. This study investigated the frequencies and risks of endocrine sequelae in childhood cancer survivors who received hematopoietic stem cell transplantation (HSCT). Methods: This study included 200 pediatric patients who underwent HSCT. Clinical and endocrinological findings were collected retrospectively. The median follow-up duration after HSCT was 14 years. Results: Endocrine complications occurred in 135 patients (67.5%). Children who underwent HSCT at pubertal age (n=100) were at higher risk of endocrine complications than those who received it at prepubertal age (79% vs. 56%, P=0.001). The most common complication was hypogonadism (40%), followed by dyslipidemia (22%). Short stature and diabetes mellitus were more prevalent in the prepubertal group, whereas hypogonadism and osteoporosis were more common in the pubertal group. Being female, pubertal age at HSCT, and glucocorticoid use were predictors of an increased risk for any complication. Radiation exposure increased the risk of short stature and hypothyroidism. Hypogonadism was significantly associated with being female, pubertal age at HSCT, and high-dose radiation. Pubertal age at HSCT also increased the risks of osteoporosis and dyslipidemia. Conclusion This study demonstrates that long-term endocrine complications are common after HSCT in children and adolescents. Age at HSCT is a critical factor for endocrine complications after HSCT. These findings suggest that surveillance strategies for endocrine complications in childhood cancer survivors should be specified according to age at HSCT.