Juan Le

Purpose To investigate the association between serum 25-hydroxyvitamin D [25(OH)D] levels and central precocious puberty (CPP) in children, with emphasis on sex-specific threshold effects and mediation pathways. Methods This cross-sectional study enrolled 494 CPP patients (female: 413; male: 81) and 2,259 age-matched healthy controls who underwent ​liquid chromatography-tandem mass spectrometry (LC-MS/MS) based 25(OH)D quantification, Tanner-Whitehouse 3 bone age assessment, and hormonal profiling. Dose-response relationships were analyzed via restricted cubic splines (RCS), and causal mediation analysis with 1,000 bootstrap resamples were quantified using structural equation models. Results CPP patients exhibited significantly lower 25(OH)D levels than controls (median (IQR): females, 20.00 (14.00–24.20) vs. 23.40 (18.10–29.22) ng/mL, P < 0.001; males, 21.60 (16.00–27.10) vs. 23.30 (18.30–28.83) ng/mL, P = 0.033), with higher deficiency rates (females: 49.6% vs. 33.0%; males: 43.2% vs. 32.8%). RCS analysis revealed inverse 25(OH)D-CPP associations, with threshold concentrations at 35.4 ng/mL (females) and 19.5 ng/mL (males).​ Each 1 ng/mL increment in serum 25(OH)D was associated with 3.6% reduced risk of advanced pubic hair maturation (adjusted OR = 0.964, P = 0.009). Sex-stratified logistic regression showed elevated CPP risks in vitamin D-insufficient/deficient groups versus sufficient counterparts: females (OR = 2.13, P = 0.037; OR = 2.26, P = 0.030) and males (OR = 3.89, P = 0.059; OR = 4.71, P = 0.034). Mediation analysis identified bone age acceleration (64.6% mediation) and gonadotropin activation (14.6%) dominated pathways in females. Conclusion Vitamin D demonstrated sex-dimorphic associations with CPP risk, requiring higher protective thresholds in females. Bone age acceleration and gonadotropin activation emerged as primary mediators in females. These findings advocated sex-specific vitamin D supplementation strategies for CPP prevention.

Objective: Optimization of maternal vitamin D (VD) status has beneficial effects on pregnancies, but little is known about it of twin pregnancies (TP). Our aim was to promote the current understanding of VD status and its associated factors in TP. Methods: We performed liquid chromatography-tandem mass spectrometry to quantify 25-hydroxyvitamin D [25(OH)D] and used the enzyme-linked immunosorbent assay method to detect vitamin D binding protein (VDBP) in 218 singleton pregnancies (SP) and 236 TP. Results: Levels of 25(OH)D and VDBP were higher in TP than SP. The 25(OH)D, free 25(OH)D, C-3 epimer of 25-hydroxyvitamin D [epi-25(OH)D], and VDBP all increased with gestational progress. Age, body mass index, and hemoglobin level were associated with VD deficiency (VDD). Analysis of covariance demonstrated that the 25(OH)D and VDBP of TP and SP still showed differences after adjusting for the above associated factors. Conclusion: Differences in VD status were found in SP and TP, suggesting that the assessment of VD status in TP should be treated with caution. High VDD prevalence is observed among pregnant Chinese women, and it is recommended to promote evaluation for VDD.

The interaction between the endocrine system and inflammation is crucial pathogenesis of depression. Our study aimed at exploring the possible relationship between sex hormones and growth differentiation factor-15 (GDF-15), a common indicator of inflammation in male patients with major depressive disorder (MDD). Methods: GDF-15 levels of 121 male MDD patients were compared with 105 healthy subjects with the help of a Cobas 8000 automatic chemiluminescence immunoanalyzer. Results: (1) MDD patients showed higher GDF-15 levels, a lower testosterone (T) level and testosterone/estradiol ratio (T/E2 ratio) than healthy subjects (all p < 0.05). (2) Serum T levels and the T/E2 ratio were inversely associated with GDF-15 serum levels (all p < 0.05). (3) HAMD-24 scores were positively correlated with the levels of GDF-15 (p < 0.01), but not with T levels, estradiol (E2) levels, and the T/E2 ratio (all p > 0.05). Conclusion: The high level of GDF-15 was correlated with a low T/E2 ratio and T deficiency in male MDD patients. The above results demonstrate that up-regulation of serum GDF-15 and down-regulation of T and T/E2 ratio may be correlated with the occurrence and severity of depression. So, changing the level of GDF-15 by regulating the proportion of sex hormones may play a key role in the prognosis and treatment of depression.