This study aims to investigate serum makorin ring finger protein 3 (MKRN3) levels in girls with idiopathic central precocious puberty (ICPP) and premature thelarche (PT), in order to determine whether circulating MKRN3 level is associated with ICPP and PT. A total of 90 girls were enrolled in the study. 30 age-matched girls were allocated for each group (ICPP, PT and healthy controls [HC], respectively). The base LH (B-LH) and E2 levels were higher in ICPP girls than those in HC and PT girls. The peak LH (P-LH) levels and P-LH/P-FSH values were obviously higher in ICPP girls than those in PT girls, while higher peak FSH (P-FSH) levels were detected in PT girls when compared to those in ICPP girls. Kisspeptin levels were lower in HC girls than those in ICPP and PT girls. MKRN3 levels were the highest in HC girls among the three groups. There were relatively strong negative correlations among MKRN3, kisspeptin and P-LH/P-FSH. Circulating MKRN3 can have an important role in the onset of ICPP and PT. However, this should not be used as an independent diagnostic criterion for diagnosing ICPP or differentiating ICPP from PT, but should be used only as an adjunctive diagnostic biomarker.

Background: The loss of hypocretin is thought to be the main pathophysiological mechanism of narcolepsy. There is strong evidence that hypocretin is related to the regulation of endocrine functions and depression. To explore thyroid hormone levels in narcolepsy patients was our aim. In addition, further is to analyze the relationship between thyroid hormone levels and sleep quality, anxiety, and depression in narcolepsy patients. Methods: There are 40 patients with narcolepsy and 40 healthy controls (HCs) were conducted. Blood samples were explored for thyroid function. Correlation analysis between thyroid hormones and clinical characteristics of narcolepsy was performed using Pearson or Spearman. Results: Narcolepsy patients had significantly lower free thyroxine (FT4) levels in comparison to controls (p ＜ 0.001). No subject was diagnosed with primary hypothyroidism. There were 4 (10 %) subjects with subclinical hypothyroidism. The serum FT4 levels were positively correlated with HAMA14 score (r = -0.343, p = 0.030) by Pearson correlation analysis. The serum TSH levels and HAMD24 score (r = -0.807 p ˂0.001), and ESS score (r = -0.317, p = 0.046) both showed a negative correction. Conclusion: Hypocretin deficiency may be associated with the regulation of thyroid hormones in narcolepsy patients. The serum thyroid hormones may affect the severity and neuropsychological functions of narcolepsy patients.