AffiliationDepartment of Endocrinology, Christie Hospital, Manchester, UK. Klissett@aol.com
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AbstractThe insulin-like growth factor I (IGF-I) generation test has the potential to assess the ability of an individual to respond to an acute bolus of growth hormone (GH), in terms of IGF-I, IGF-binding protein 3 and acid-labile subunit responses. This article will discuss something of the history of the IGF-I generation test, and review some of the major studies to date. The IGF-I generation test was first used in adults by Lieberman et al., who studied the effects of ageing and oestrogen administration, and suggested that decreased responsiveness to GH occurs with increasing age and oral oestrogen administration. Our results, however, show that, while activity of the GH/IGF-I axis declines with age, peripheral responsiveness to GH is not affected. As in the Lieberman study, we found that oral oestrogen replacement reduces responses of GH-dependent peptides to GH stimulation in healthy post-menopausal women. Transdermal oestrogen administration also reduced responsiveness to GH, although to a lesser degree than orally administered oestrogen. In addition, utilizing a non-weight-based dose of GH we have demonstrated that obese individuals produce greater increases in IGF-I following an acute bolus of GH. In GH deficiency (GHD), data suggesting enhanced peripheral responsiveness should be interpreted with caution, and with awareness of differences between these groups in terms of age and obesity. The IGF-I generation test may allow a fresh approach to unanswered questions in the field of GHD, but as the IGF-I response to GH is not strictly associated with protein anabolism or clinical benefit, the question remains whether this test will predict the effect of longer-term GH administration.
CitationThe insulin-like growth factor I generation test in adults. 2004, 62 Suppl 1:44-9 Horm. Res.
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- Authors: Yuen KC, Cook DM, Rumbaugh EE, Cook MB, Dunger DB
- Issue date: 2006
- The insulin-like growth factor I generation test: resistance to growth hormone with aging and estrogen replacement therapy.
- Authors: Lieberman SA, Mitchell AM, Marcus R, Hintz RL, Hoffman AR
- Issue date: 1994 May
- IGF-I and IGF binding protein-3 levels during initial GH dosage step-up are indicators of GH sensitivity in GH-deficient children and short children born small for gestational age.
- Authors: Ranke MB, Traunecker R, Martin DD, Schweizer R, Schwarze CP, Wollmann HA, Binder G
- Issue date: 2005
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- Authors: Jørgensen JO, Christensen JJ, Krag M, Fisker S, Ovesen P, Christiansen JS
- Issue date: 2004
- Impairment of GH responsiveness to combined GH-releasing hormone and arginine administration in adult patients with Prader-Willi syndrome.
- Authors: Grugni G, Marzullo P, Ragusa L, Sartorio A, Trifirò G, Liuzzi A, Crinò A, Genetic Obesity Study Group of the Italian Society of Pediatric Endocrinology and Diabetology.
- Issue date: 2006 Oct