Background: Kisspeptin and delta-like 1 homolog (DLK1) are neuropeptides that reportedly play an important role in pubertal timing by activating and inhibiting the hypothalamic-pituitary-gonadal axis, respectively. Consequently, serum kisspeptin and DLK1 levels may be novel biomarkers for differentiating between central precocious puberty (CPP) and premature thelarche (PT) in girls and used to monitor CPP treatment.Purpose: To compare baseline serum kisspeptin and DLK1 levels in girls with CPP at diagnosis and after treatment to age-matched girls with PT. Methods: This prospective longitudinal study included girls with precocious puberty and girls with PT who experienced breast development before 8 years of age and peak luteinizing hormone levels of ≥6 versus <6 IU/L after a gonadotropin-releasing hormone (GnRH) stimulation test. Serum kisspeptin and DLK1 levels were determined in both groups at baseline and after 6 months of GnRH analog treatment in the CPP group and analyzed by enzyme-linked immunosorbent assay. Results: The study divided a total of 48 girls into CPP (n=24; mean age, 7.7±0.7 years) and PT (n=24; mean age, 7.4±0.8 years) groups. The baseline median serum kisspeptin levels were 50.5 pg/mL (range, 38.2–77 pg/mL) and 49.5 pg/mL (range, 39.7–67.6 pg/mL), respectively (P=0.89), while the baseline median serum DLK1 levels were 6.5 ng/mL (range, 5.9–7.5 ng/mL) and 6 ng/mL (4.4–14.4 ng/mL), respectively (P=0.68). After 6 months of GnRH analog treatment in the CPP group, the median serum kisspeptin level was lower (46.4 ng/mL; range, 37.1–60 ng/mL) than that at baseline (P=0.002), while the median serum DLK1 level was higher (7 ng/mL; range, 6.7–8.9) than that at baseline (P=0.002). Conclusion Our findings suggest that baseline serum kisspeptin and DLK1 levels are not reliable biomarkers for differentiating between CPP and PT. However, significant changes in serum kisspeptin and DLK1 levels may be used to monitor CPP treatment.

Purpose: Intravenous gonadotropin-releasing hormone (IV GnRH) testing is the gold standard for confirming a central precocious puberty (CPP) diagnosis. However, this test is not widely available commercially. Therefore, our study aim was to establish cutoff values for basal gonadotropin level and gonadotrophin responses to a 100-μg subcutaneous IV GnRH test that can distinguish between CPP and premature thelarche (PT) to discover a simple method to detect CPP. Methods: Girls between the ages of 6 and 8 years who attended the pediatric endocrinology outpatient clinic at our tertiary hospital between 2019 and 2022 were included in this study. They were evaluated for breast development, and a subcutaneous 100-μg GnRH test was administered by measuring the luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels in blood samples at baseline and then 30, 60, 90, and 120 minutes after injection. CPP is characterized by increased height velocity, advanced bone age, and progression of breast development. The cutoff value for diagnosis of CPP was determined using a receiver operating characteristic (ROC) analysis. Results: In 86 Thai girls (56 with CPP and 30 with PT), the ROC analysis showed 71.4% and 100% sensitivity and specificity, respectively, for basal LH (cutoff ≥ 0.2 IU/L) plus the basal LH/FSH ratio (cutoff ≥ 0.1). The optimal cutoff values for peak LH (cutoff ≥ 7 IU/L) demonstrated a sensitivity of 94.6% and a specificity of 100%, whereas the LH value at 30 and 60 minutes after injection (cutoff ≥ 6 IU/L) demonstrated sensitivities of 92.9% and 94.6% and a specificity of 100%, respectively Conclusion Combining the basal LH (cutoff: 0.2 IU/L) and the basal LH/FSH ratio (cutoff: 0.1) can easily and cost-effectively diagnose CPP in a girl in breast Tanner stage II.

Background: Kisspeptin and delta-like 1 homolog (DLK1) are neuropeptides that reportedly play an important role in pubertal timing by activating and inhibiting the hypothalamic-pituitary-gonadal axis, respectively. Consequently, serum kisspeptin and DLK1 levels may be novel biomarkers for differentiating between central precocious puberty (CPP) and premature thelarche (PT) in girls and used to monitor CPP treatment.Purpose: To compare baseline serum kisspeptin and DLK1 levels in girls with CPP at diagnosis and after treatment to age-matched girls with PT. Methods: This prospective longitudinal study included girls with precocious puberty and girls with PT who experienced breast development before 8 years of age and peak luteinizing hormone levels of ≥6 versus <6 IU/L after a gonadotropin-releasing hormone (GnRH) stimulation test. Serum kisspeptin and DLK1 levels were determined in both groups at baseline and after 6 months of GnRH analog treatment in the CPP group and analyzed by enzyme-linked immunosorbent assay. Results: The study divided a total of 48 girls into CPP (n=24; mean age, 7.7±0.7 years) and PT (n=24; mean age, 7.4±0.8 years) groups. The baseline median serum kisspeptin levels were 50.5 pg/mL (range, 38.2–77 pg/mL) and 49.5 pg/mL (range, 39.7–67.6 pg/mL), respectively (P=0.89), while the baseline median serum DLK1 levels were 6.5 ng/mL (range, 5.9–7.5 ng/mL) and 6 ng/mL (4.4–14.4 ng/mL), respectively (P=0.68). After 6 months of GnRH analog treatment in the CPP group, the median serum kisspeptin level was lower (46.4 ng/mL; range, 37.1–60 ng/mL) than that at baseline (P=0.002), while the median serum DLK1 level was higher (7 ng/mL; range, 6.7–8.9) than that at baseline (P=0.002). Conclusion Our findings suggest that baseline serum kisspeptin and DLK1 levels are not reliable biomarkers for differentiating between CPP and PT. However, significant changes in serum kisspeptin and DLK1 levels may be used to monitor CPP treatment.

Background: Kisspeptin and delta-like 1 homolog (DLK1) are neuropeptides that reportedly play an important role in pubertal timing by activating and inhibiting the hypothalamic-pituitary-gonadal axis, respectively. Consequently, serum kisspeptin and DLK1 levels may be novel biomarkers for differentiating between central precocious puberty (CPP) and premature thelarche (PT) in girls and used to monitor CPP treatment.Purpose: To compare baseline serum kisspeptin and DLK1 levels in girls with CPP at diagnosis and after treatment to age-matched girls with PT. Methods: This prospective longitudinal study included girls with precocious puberty and girls with PT who experienced breast development before 8 years of age and peak luteinizing hormone levels of ≥6 versus <6 IU/L after a gonadotropin-releasing hormone (GnRH) stimulation test. Serum kisspeptin and DLK1 levels were determined in both groups at baseline and after 6 months of GnRH analog treatment in the CPP group and analyzed by enzyme-linked immunosorbent assay. Results: The study divided a total of 48 girls into CPP (n=24; mean age, 7.7±0.7 years) and PT (n=24; mean age, 7.4±0.8 years) groups. The baseline median serum kisspeptin levels were 50.5 pg/mL (range, 38.2–77 pg/mL) and 49.5 pg/mL (range, 39.7–67.6 pg/mL), respectively (P=0.89), while the baseline median serum DLK1 levels were 6.5 ng/mL (range, 5.9–7.5 ng/mL) and 6 ng/mL (4.4–14.4 ng/mL), respectively (P=0.68). After 6 months of GnRH analog treatment in the CPP group, the median serum kisspeptin level was lower (46.4 ng/mL; range, 37.1–60 ng/mL) than that at baseline (P=0.002), while the median serum DLK1 level was higher (7 ng/mL; range, 6.7–8.9) than that at baseline (P=0.002). Conclusion Our findings suggest that baseline serum kisspeptin and DLK1 levels are not reliable biomarkers for differentiating between CPP and PT. However, significant changes in serum kisspeptin and DLK1 levels may be used to monitor CPP treatment.

Background: Kisspeptin and delta-like 1 homolog (DLK1) are neuropeptides that reportedly play an important role in pubertal timing by activating and inhibiting the hypothalamic-pituitary-gonadal axis, respectively. Consequently, serum kisspeptin and DLK1 levels may be novel biomarkers for differentiating between central precocious puberty (CPP) and premature thelarche (PT) in girls and used to monitor CPP treatment.Purpose: To compare baseline serum kisspeptin and DLK1 levels in girls with CPP at diagnosis and after treatment to age-matched girls with PT. Methods: This prospective longitudinal study included girls with precocious puberty and girls with PT who experienced breast development before 8 years of age and peak luteinizing hormone levels of ≥6 versus <6 IU/L after a gonadotropin-releasing hormone (GnRH) stimulation test. Serum kisspeptin and DLK1 levels were determined in both groups at baseline and after 6 months of GnRH analog treatment in the CPP group and analyzed by enzyme-linked immunosorbent assay. Results: The study divided a total of 48 girls into CPP (n=24; mean age, 7.7±0.7 years) and PT (n=24; mean age, 7.4±0.8 years) groups. The baseline median serum kisspeptin levels were 50.5 pg/mL (range, 38.2–77 pg/mL) and 49.5 pg/mL (range, 39.7–67.6 pg/mL), respectively (P=0.89), while the baseline median serum DLK1 levels were 6.5 ng/mL (range, 5.9–7.5 ng/mL) and 6 ng/mL (4.4–14.4 ng/mL), respectively (P=0.68). After 6 months of GnRH analog treatment in the CPP group, the median serum kisspeptin level was lower (46.4 ng/mL; range, 37.1–60 ng/mL) than that at baseline (P=0.002), while the median serum DLK1 level was higher (7 ng/mL; range, 6.7–8.9) than that at baseline (P=0.002). Conclusion Our findings suggest that baseline serum kisspeptin and DLK1 levels are not reliable biomarkers for differentiating between CPP and PT. However, significant changes in serum kisspeptin and DLK1 levels may be used to monitor CPP treatment.