Unaltered ratio of circulating levels of growth hormone/GH isoforms in adults with Prader-Willi syndrome after GHRH plus arginine administration

A. E. Rigamonti, G. Grugni, N. Marazzi, S. Bini, M. Bidlingmaier, A. Sartorio

Research output: Contribution to journalArticle

Abstract

Human growth hormone (GH) is a heterogeneous protein hormone consisting of several isoforms, the most abundant being 22kDa- and 20kDa-GH. The availability of analytical methods to measure these GH isoforms might represent a valuable diagnostic tool to investigate GH hyposecretory states, including Prader-Willi syndrome (PWS), one of the most common causes of syndromic obesity. The aim of the present study was to measure circulating levels of 22kDa- and 20kDa-GH in PWS adults (n=14; M/F: 5/9; genotype DEL15/UPD15: 12/2; age: 19.0±3.7years; BMI: 29.9±8.7kg/m2) after combined GH releasing hormone (GHRH) plus arginine (ARG) administration. The results were analysed subdividing the study population in obese vs. nonobese (6/8) and GH deficient vs. nonGH deficient (GHD) (6/8) subjects, according to appropriate BMI-related diagnostic cut-off limits of GH peak response to the provocative test. Circulating levels of 22kDa-GH were measured by a chemiluminescent method based on a detection monoclonal antibody targeting an epitope in the loop connecting helix 1 and 2 of GH, which is missing in 20kDa-GH; the 20kDa-GH was measured using a time resolved fluorescence assay based on two monoclonal antibodies with no cross-reactivity to 22-kDa GH.GHRH plus ARG significantly stimulated the secretions of 22. kDa- and 20. kDa-GH in nonobese (at 30, 45, 60 and 90. min and at 45, 60, 90 and 120. min vs. 0. min, p.

Original languageEnglish
Pages (from-to)168-173
Number of pages6
JournalGrowth Hormone and IGF Research
Volume25
Issue number4
DOIs
Publication statusPublished - Aug 1 2015

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Keywords

  • GH deficiency
  • GH isoforms
  • GHRH plus arginine
  • Obesity
  • Prader-Willi syndrome

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

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