Insulin-like Growth Factor 1, but Not Insulin-Like Growth Factor-Binding Protein 3, Predicts Central Precocious Puberty in Girls 6–8 Years Old: A Retrospective Study

Abstract

<b><i>Background:</i></b> Central precocious puberty (CPP) in females is characterized by thelarche before 8 years of age. Evidence of reproductive axis activation confirms the diagnosis (basal serum luteinizing hormone (LH) ≥0.3 IU/L or LH-releasing hormone (LHRH)-stimulated LH ≥5 IU/L). Stimulation testing is the diagnostic gold standard but is time-consuming and costly. Serum levels of insulin-like growth factor-1 (IGF-1) and insulin-like growth factor-binding protein 3 (IGFBP-3) are increased in girls with CPP. <b><i>Objective:</i></b> The aim of the study was to assess the utility of serum IGF-1 and IGFBP-3 in identifying CPP in girls aged 6–8 years. <b><i>Methods:</i></b> The study was a single-center retrospective study. Girls with confirmed CPP (<i>n</i> = 44) and isolated premature precocious adrenarche/ precocious thelarche (PA/PT, <i>n</i> = 16) had baseline biochemical profiling and LHRH stimulation testing. Serum IGF-1 and IGFBP-3 results were converted to standard deviation scores (SDS). Correlations were calculated and receiver operating characteristic curves were plotted. <b><i>Results:</i></b> Girls with CPP had higher basal and peak LH, IGF-1 SDS, and growth velocity (<i>p</i> &#x3c; 0.05). IGF-1 SDS correlated positively with basal and peak LH (<i>p</i> &#x3c; 0.05). IGF-1 SDS (1.75–2.15) differentiated CPP and PA/PT with 89% sensitivity and 56% specificity (basal LH) and 94% specificity and 55% sensitivity (peak LH). IGFBP-3 SDS did not differ between groups or by CPP parameters. <b><i>Conclusions:</i></b> In clinical practice, IGF-1 SDS may be an additional tool for identifying CPP in girls aged 6 to 8 years when baseline clinical and laboratory diagnostic criteria are inconclusive, possibly avoiding more time-consuming and costly procedures.