Introduction: Ghrelin concentrations decline during puberty by an unclear mechanism. Acylated ghrelin (AG) is unstable in sampling tubes, but no standardized sampling protocol exists. We hypothesized that ghrelin levels decrease as a consequence of increased gonadotropin-releasing hormone (GnRH) signalling and that the addition of a protease inhibitor to sampling tubes preserves the AG levels.

Methods: In this randomized, placebo-controlled, cross-over study, 13 girls with suspected central precocious puberty were included. They performed an adjusted GnRH stimulation test twice and were given Relefact LHRH (R)(100 mu g/m(2)) or saline in a randomized order. Blood was sampled repeatedly for 150 min for the analysis of hormone concentrations. Oestradiol levels were only measured at baseline. The protease inhibitor 4-(2-aminoethyl) benzenesulfonyl fluoride hydrochloride (AEBSF) was added to the sampling tubes. Specific ELISA kits were used for the analysis of AG and desacylated ghrelin (DAG) levels.

Results: Neither AG nor DAG levels changed after GnRH analogue injection in comparison to saline. The addition of AEBSF preserved AG levels (650.1 +/- 257.1 vs. 247.6 +/- 123.4 pg/mL, p < 0.001) and decreased DAG levels (51.9 [12.5-115.7] vs. 143.5 [71.4-285.7] pg/mL, p < 0.001). Both AG and DAG levels were inversely associated with insulin levels (r = -0.73, p = 0.005, and r = -0.78, p = 0.002, respectively). AG levels were inversely associated with oestradiol levels (rho = -0.57, p = 0.041).

Conclusion: Ghrelin levels do not decrease following a pharmacological dose of a GnRH analogue in the short term in girls. Addition of a protease inhibitor to the sampling tubes decreases AG degradation, resulting in preserved AG and decreased DAG levels. (C) 2022 The Author(s). Published by S. Karger AG, Basel

OBJECTIVES: Kisspeptin plays a major role in the onset of puberty by stimulating the gonadotropin-releasing hormone (GnRH) neurons. The aim of this study was to investigate whether GnRH inhibits kisspeptin secretion via a negative feedback mechanism and potential associations between kisspeptin levels and other hormones of importance for pubertal onset.

METHODS: Thirteen girls with suspected central precocious puberty underwent a GnRH stimulation test twice in a randomized, placebo-controlled manner. Blood was sampled up to 150 min after an IV injection of either Relefact LHRH® or saline. The levels of kisspeptin, acylated ghrelin, ultrasensitive oestradiol, luteinizing hormone (LH), follicle-stimulating hormone (FSH), insulin and glucose were analysed.

RESULTS: Baseline kisspeptin levels ranged from 9.9 to 201.6 pg/mL. Neither area under the curve for kisspeptin levels nor peaks were significantly lower after the GnRH injection compared to placebo. Baseline kisspeptin and glucose levels tended to be associated (rho=0.55, p=0.051) but no other associations were found between kisspeptin and other hormones.

CONCLUSIONS: Basal levels of kisspeptin vary widely in young girls. We found no evidence of a negative feedback mechanism of GnRH on kisspeptin in this small pilot study. The suggested association between kisspeptin and glucose levels needs further investigations.

OBJECTIVES: To compare the usefulness of the classical definition of delayed puberty (DP) in boys with puberty nomograms and to describe the management of DP in boys in a hospital-based setting.

STUDY DESIGN: Observational retrospective multicentre study with a short-term follow-up.

SETTING AND PARTICIPANTS: Boys diagnosed with DP during 2013-2015 at paediatric departments in four counties in central Sweden. The medical records of 165 boys were reviewed.

PRIMARY AND SECONDARY OUTCOME MEASURES: Number of boys with DP after re-evaluation of the diagnosis according to the classical definition in comparison with puberty nomograms. Description of investigations performed and treatment provided to boys with DP.

RESULTS: In total, 45 and 58 boys were found to have DP according to the classical definition and the nomograms, respectively. Biochemical and/or radiological testing was performed in 91% of the 58 boys, but an underlying disease was only found in 9% of them. Approximately 79% of the boys received testosterone treatment, either as injections of testosterone enanthate or as testosterone undecanoate.

CONCLUSIONS: Puberty nomograms may be helpful instruments when diagnosing pubertal disorders in boys as they are not limited to an age close to 14 years and also identify boys with pubertal arrest. The majority of boys with DP undergo biochemical or radiological examinations, but underlying diseases are unusual emphasising the need for structural clinical practice guidelines for this patient group.