Basal serum luteinising hormone cut‐off, and its utility and cost‐effectiveness for aiding the diagnosis of the onset of puberty in girls with early stages of breast development

Abstract Objective To determine basal and gonadotrophin‐releasing hormone analogue (GnRHa)‐stimulated peak luteinising hormone (LH) cut‐offs to diagnose onset of early or normal puberty in girls with each Tanner stage of breast (II and III). Design, Patients and Measurements A retrospective study of 601 girls with breast onset before 8 years of age who underwent GnRHa test was conducted. Patients were categorized as CPP and premature thelarche. Each group was divided into two subgroups; Tanner II and III. Cost‐effectiveness analysis was performed. Results In comparison with basal LH cut‐off of 0.3 IU/L, basal LH cut‐off of 0.2 IU/L had comparable specificity (Tanner II: 98.0% vs 94.8%, Tanner III: 98.8% vs 93.8%), but greater sensitivity (Tanner II: 28.3% vs 41.7%, Tanner III: 45.2% vs 59.3%). Specificity of basal LH cut‐off of 0.2 IU/L was not inferior to that of the traditionally used peak LH of 5 IU/L. Using basal LH cut‐off of 0.2 IU/L followed by GnRHa test in girls with negative basal LH was more cost‐saving when compared with using the cut‐off of 0.3 IU/L. Moreover, using basal LH cut‐off of 0.2 IU/L followed by GnRHa test provided a cost reduction when compared with performing GnRHa test in all patients. Conclusions Basal serum LH cut‐off of 0.2 IU/L could be a simple and cost‐saving tool for initial diagnosis of onset of early or normal puberty in girls with Tanner II and III before proceeding to GnRH testing.