Comparison of Spexin and Phoenixin-20 Levels in Girls With Central Precocious Puberty, Premature Thelarche, and Healthy Controls

This was a prospective, observational study conducted in a pediatric endocrinology outpatient clinic. The study population consisted of girls younger than 8 years of age who presented between December 2024 and December 2025. Participants were categorized into three groups: girls diagnosed with central precocious puberty (CPP), girls with premature thelarche (PT), and healthy age-matched control subjects. The CPP group: 33 patients, PT group: 57 patients, and healthy controls: 53 patients.

The diagnosis of central precocious puberty was based on clinical findings, auxological data, bone age assessment, and hormonal evaluation according to standard pediatric endocrinology criteria. Premature thelarche was defined as isolated breast development without other signs of pubertal progression or activation of the hypothalamic-pituitary-gonadal axis.

Clinical and anthropometric data, including age, height, weight, body mass index, bone age, were recorded. Blood samples were obtained under standardized conditions, and also LH-RH stimulation test was applied in CPP and PT groups. Basal and stimulated FSH and LH hormone levels were examined. In addition, serum spexin and phoenixin-20 concentrations were measured using enzyme-linked immunosorbent assay kits in accordance with the manufacturers' instructions.

The primary objective of the study was to investigate whether serum spexin and phoenixin-20 levels differ between girls with CPP and those with PT or healthy controls, and whether these biomarkers could aid in distinguishing CPP from other causes of early pubertal signs.