Elevated Random Luteinizing Hormone Is Unreliable Indicator for Pubertal Suppression in Girls Treated with Monthly Leuprolide for Idiopathic Central Precocious Puberty

Objective: Longitudinal data in random luteinizing hormone (LH) concentrations in patients with idiopathic central precocious puberty (ICPP) during treatment are limited. Therefore, we sought to evaluate random LH and estradiol concentrations during monthly leuprolide injection and its associations with pubertal progression and final adult height (FAH) in girls with ICPP.

Methods: Medical records of 27 ICPP girls who attained FAH were reviewed. Patients’ height, weight, Tanner stage, growth rate (GR), bone age, random LH, follicular-stimulating hormone (FSH) and estradiol were monitored until FAH.

Results: Treatment was started at mean (±SD) age of 8.1±0.6 years with duration of 3.9±0.2 years. At 6 months of follow-up, random LH (p=0.048), FSH (p<0.001) and estradiol (p=0.023) were significantly decreased from baseline. Thereafter, random LHs were well suppressed. GR was gradually declined to a prepubertal norm at month 12. Seventeen patients (63%) exhibited pubertal LH at least once at some points of treatment. Further, 43 of 116 (37%) LH measurements were in pubertal range; 0.6-2.9 (immunoradiometric assays) and 0.3-0.83 IU/L (immunochemiluminescent assay). However, no patients showed signs of pubertal progression during pubertal LH episodes. After treatment, the patients attained FAH that higher than predicted adult height (p<0.0001) and target height (p=0.03). Random LH, FSH and estradiol at any time points did not correlate with GR nor FAH.

Conclusion: Elevated random LH is commonly found in ICPP girls during monthly leuprolide treatment. However, it does not associate with clinical progression of puberty nor decreased FAH suggesting that it is not a reliable method for CPP monitoring.