Combining Pituitary Height and Basal LH for Diagnosing Idiopathic Central Precocious Puberty: A Retrospective Study of 130 Girls

Background The gonadotropin-releasing hormone (GnRH) stimulation test is the gold standard for diagnosing central precocious puberty (CPP), but it is invasive and inconvenient. Pituitary height measured on MRI may provide a complementary non-invasive marker. Objective To evaluate the diagnostic performance of pituitary height for distinguishing idiopathic central precocious puberty (ICPP) from premature thelarche (PT) and to assess whether combining pituitary height with baseline luteinizing hormone (LH) improves accuracy. Methods This retrospective study included 130 girls under 8 years presenting with breast development. Pituitary height was measured on sagittal and coronal T1-weighted MRI. Baseline and stimulated gonadotropins were also measured. Diagnostic accuracy was evaluated using ROC analysis, and logistic regression assessed the predictive contribution of pituitary height. Results Pituitary height was significantly greater in the ICPP group (5.61 ± 1.00 mm) than in the PT group (4.15 ± 0.75 mm; p < 0.001). Pituitary height correlated positively with baseline LH (r = 0.35), peak LH (r = 0.28), and peak LH/FSH ratio (r = 0.26). Logistic regression indicated that each 0.1 mm increase in pituitary height raised the ICPP likelihood 18-fold (P < 0.001). The ROC analysis for pituitary height showed an AUC of 0.915, with a 4.7 mm cutoff providing 90% sensitivity and 86.5% specificity. Combining pituitary height with baseline LH levels improved diagnostic accuracy, yielding an AUC of 0.92, sensitivity of 95%, and specificity of 82%. Conclusion MRI-measured pituitary height, especially when combined with baseline LH, provides a non-invasive, effective diagnostic alternative to the GnRH stimulation test for ICPP.