Endocrine Abstracts

Background: Historically, a second LHRH stimulation test has been the gold standard test for the evaluation of biochemical evidence of pubertal suppression in patients with central precocious puberty (CPP) following commencement of GnRH analogue therapy. However, this test is time-consuming, costly, and uncomfortable for patients.

Aims/objective: To analyse the validity of the basal LH level as a predictor to the peak LH value.

Method: We reviewed 10-years’ worth of data (01/012013–31/12/2022, inclusive) as part of a service evaluation. Patients were identified from the test-results database. Electronic patient notes and biochemistry results were reviewed. Inclusion criteria included patients diagnosed with CPP based on an LH value >5 IU/L on the LHRH stimulation test, and subsequently commenced on GnRH agonist therapy. Data analysis was performed for the correlation between the basal and peak LH in the second LHRH test after commencing therapy, using a grid for evaluating a clinical test. Basal LH of ≤0.5 IU/L and peak LH value of ≤1 IU/L were considered as biochemical indicators of adequate pubertal suppression.

Results: 41 patients fulfilled the criteria for CPP (85% female, n=35). The median age of presentation was 6.7 years in girls, and 7 years in boys. 51% of the cohort were identified as white/white British (n=21). In 87% of the cohort, there was no family history of precocious puberty (n=34). Breast enlargement (Tanner 2) was the main presenting symptoms in girls, compared to pubic hair and a testicular volume of 4–6 mLs in boys. Statistical analysis showed that a baseline LH of ≤0.5 IU has a 87.5% positive predictive value for a peak LH ≤1 IU/L on the repeat LHRH test, which indicates adequate puberty suppression. Also, a baseline LH ≤0.5 IU/L had a 100% sensitivity and 85% specificity for an adequate puberty suppression.

Discussion/conclusion: Basal LH serum sample of ≤0.5 IU/L, is a reliable indicator for puberty suppression in patients on GnRH analogue treatment for CPP, with good sensitivity and specificity. This will reduce the number of blood draws compared to the LHRH test. However, larger data need to be reviewed.