Insulin Growth Factor 1 Predicts Central Precocious Puberty in Girls 6 to 8 Years-Old: A Retrospective Study

Background: 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 LH ≥ 0.3 IU/L or luteinizing hormone-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. Objective: To assess the utility of serum IGF-1 and IGFBP-3 in identifying CPP in girls aged 6 to 8 years old. Methods: The study was a single-center retrospective study. Girls with confirmed CPP (n=44) and isolated premature adrenarche/thelarche (PA/PT, n=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. Results: Girls with CPP had higher basal and peak LH, IGF-1 SDS, and growth velocity (p<0.05). IGF-1 SDS correlated positively with basal and peak LH (p<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. Conclusions: In clinical practice, IGF-1 SDS may be an additional tool for identifying CPP in girls aged 6 to 8 years-old when baseline clinical and laboratory diagnostic criteria are inconclusive, possibly avoiding more invasive procedures.