Soluble alpha klotho concentrations are resistant to short-term stimulation and suppression of growth hormone

de Oliveira Longo Schweizer Junia Ribeiro; Katharina Schilbach; Olivia Tausendfreund; Michael Haenelt; Anica Gagliardo; Jochen Schopohl; Michael Drey; Martin Bidlingmaier

doi:10.1530/endoabs.99.P527

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Endocrine Abstracts (2024) 99 P527 | DOI: 10.1530/endoabs.99.P527

ECE2024 Poster Presentations Pituitary and Neuroendocrinology (120 abstracts)

Soluble alpha klotho concentrations are resistant to short-term stimulation and suppression of growth hormone

Junia Ribeiro de Oliveira Longo Schweizer ¹ , Katharina Schilbach ¹ , Olivia Tausendfreund ¹ , Michael Haenelt ¹ , Anica Gagliardo ¹ , Jochen Schopohl ¹ , Michael Drey ¹ & Martin Bidlingmaier ¹

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¹Ludwig Maximilians University, LMU Klinikum; Med. Klinik und Poliklinik IV, München

Background: Serum soluble alpha klotho (sαKL) is a circulating protein which had been shown to be very high in active acromegaly, and significantly reduced after disease control. Therefore, sαKL has been suggested as a new biomarker for growth hormone (GH) excess. In this study, we aimed to evaluate the impact of short-term stimulation and suppression of GH and acute modulation of glucose metabolism on sαKL concentrations.

Methods: Serum sαKL was measured by ELISA (IBL, Hamburg, Germany). Samples were collected during GHRH-Arginine test (0, 30, 60, 90 and 120 min.) in geriatric patients without GH deficiency (n=9, 72-94 years, 5 males) and in a cohort of patients with proven GH deficiency (GHD, n=10, 22-71years, 5 males). We also evaluated sαKL in healthy participants (n=22, aged 22-52 year, 8 males) during oral glucose tolerance test (OGTT: 0,30,60,90,120 and 180 min.).

Results: As expected, GH concentrations (mean±SD, ng/dl) significantly increased during GHRH-Arginine test in participants without GHD (baseline: 0.78±0.48 vs _peakGH: 14.7±7.8, P<0.05) but not in patients with GHD (baseline: 0.36±0.5 vs _peakGH: 1.26±1.1, p>0.05). Neither in aged patients without GHD (baseline sαKL: 668±174 vs _120minsαKL: 654±168, p>0.05) nor in patients with GHD (baseline: 831±221 vs _120minsαKL:827±271, p>0.05) sαKL concentrations (mean±SD, pg/ml) varied significantly during GHRH-Arginine test. During OGTT, GH concentrations decreased, and glucose and insulin increased, but sαKL concentrations did not change significantly (p>0.05 for all comparisons).

Conclusion: In contrast to chronic GH excess in acromegaly, sαKL concentrations are not significantly affected by short-term stimulation and suppression of GH. Furthermore, acute elevation of glucose and insulin do not significantly impact sαKL concentrations in healthy subjects.