The worldwide incidence of precocious puberty, which is associated with negative health outcomes, is increasing. Several studies have suggested that environmental factors contribute to the development of precocious puberty alongside genetic factors. Some epidemiological studies have provided limited evidence suggesting an association between exposure to air pollution and changes in pubertal development. This systematic review aimed to summarize existing evidence on the association between air pollution exposure and precocious puberty. Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines, we searched two databases (PubMed and Web of Science) until August 2023. The included studies assessed the association between air pollutant exposure and the risk of precocious puberty, early menarche, or pubertal development. Two authors independently performed study selection and data extraction. A meta-analysis and analysis of the risk of bias were infeasible due to the limited number of studies and the heterogeneity among them. The literature search resulted in 184 studies, from which we included six studies with sample sizes ranging from 437 to 4,074 participants. The studies reported heterogeneous outcomes. Four studies found that increased exposure to air pollution was related to earlier pubertal onset. One study was inconclusive, and another suggested that air pollutant exposure may delay the onset of thelarche. Most studies suggest that exposure to air pollutants accelerates pubertal development; however, the results from the available studies are inconsistent. More extensive and well-designed longitudinal studies are required for a comprehensive understanding of the association between air pollution and precocious puberty.
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A notable secular trend in early puberty onset has been described over the past few decades. Also, the prevalence and incidence of precocious puberty is increasing not only in Korea, but also around the world. The manifestation of secondary sex characteristics before 8 years in girls and 9 years in boys is defined as precious puberty. The causes of precocious puberty can be classified as gonadotropin releasing hormone (GnRH)-dependent, also known as central precocious puberty (CPP), or GnRH-independent. Evaluation of patient with precocity requires detailed examination of the clinical manifestation, GnRH stimulation test, and imaging of the central nervous system if indicated. The standard treatment for CPP is GnRH agonist, which is beneficial for adequate pubertal development and preservation of final adult height. In this paper, we investigate the diagnosis and adequate treatment of CPP.
To investigate brain magnetic resonance imaging (MRI) findings in patients with central precocious puberty (CPP) by age at onset and sex.
We included 130 CPP patients with brain MRI findings of the pituitary gland treated at Ewha Womans University Mokdong Hospital between February 2007 and October 2013 and divided them by age and sex: boys, girls aged ≤6 years, and girls aged >6 years. The control group comprised 224 patients who underwent brain MRIs, and we compared their incidental brain findings with those of the CPP group.
In the CPP subgroups who underwent pituitary MRIs, the frequency of incidental brain lesions was 31.6% in boys, 47.1% in girls ≤6 years and 29.8% in girls >6 years. The incidence of pituitary abnormalities was 42.1% in boys, 64.7% in girls ≤6 years and 47.9% in girls >6 years. Among pituitary abnormalities, pituitary hypoplasia had a significantly higher incidence rate in girls ≤6 years (41.2%) than in boys (15.8%) or girls >6 years (13.8%, P=0.027). Hypothalamic hamartomas were detected in one girl aged ≤6 years and in one boy, but not in girls aged 6 years (P=0.075). The incidence of pineal cysts was higher in the CPP groups and significantly higher in girls ≤6 years (47.1%) than in the control group (11.2%, P=0.001).
There was a higher incidence of brain abnormalities on pituitary MRIs and a higher incidence of pineal cysts, possibly associated with CPP pathogenesis, in younger CPP patients than in other patients.
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