Cranially irradiated adult cancer survivors may have normal spontaneous GH secretion in the presence of discordant peak GH responses to stimulation tests (compensated GH deficiency).

2.50
Hdl Handle:
http://hdl.handle.net/10541/54033
Title:
Cranially irradiated adult cancer survivors may have normal spontaneous GH secretion in the presence of discordant peak GH responses to stimulation tests (compensated GH deficiency).
Authors:
Darzy, Ken H; Thorner, Michael O; Shalet, Stephen M
Abstract:
CONTEXT: We have previously demonstrated that spontaneous (physiological) GH secretion was entirely normal in cranially irradiated patients who had normal individual peak GH responses to the insulin tolerance test (ITT) but reduced maximal somatotroph reserve as indicated by substantially reduced group GH responses to the GHRH + arginine stimulation test (AST). The normality of spontaneous GH secretion was attributed to a compensatory increase in hypothalamic stimulatory input within a partially damaged hypothalamic-pituitary (h-p) axis. It is unknown, however, if such compensatory stimulation can also maintain normality of GH secretion in those who fail the ITT but pass the GHRH + AST. STUDY SUBJECTS AND DESIGN: We studied 24-h spontaneous GH secretion by 20-min sampling both in the fed state (n = 11) and in the last 24 h of a 33-h fast (n = 9) in adult cancer survivors with subnormal peak GH responses to the ITT but either normal or relatively less attenuated peak GH responses to the GHRH + AST. The study was conducted 8.3 +/- 1.8 (range 2-23) years after cranial irradiation for nonpituitary brain tumours (n = 9) or leukaemia/lymphoma (n = 2) in comparison with 30 normal controls (fasting, 14). RESULTS: Previously published diagnostic thresholds for the ITT, GHRH + AST and spontaneous GH secretion were used to characterize GH secretion. Four of the 11 patients with impaired stimulated responses to both tests showed only minor discordancies between stimulated and spontaneous GH secretion. Two of the remaining seven patients had subnormal spontaneous GH secretion. However, spontaneous GH secretion, both individually and as a group, was entirely normal in the remaining five patients who had impaired GH responses to the ITT but normal individual responses to the GHRH + AST; in these five patients, IGF-I standard deviation scores (SDS; -2.7 to -0.8) were significantly reduced to a moderate degree compared with normals. CONCLUSIONS: In cranially irradiated adult cancer survivors, it cannot be assumed that failure to pass the ITT in isolation reflects severe GH deficiency (GHD). It appears that in some patients near-maximal compensatory overdrive of the partially damaged somatotroph axis may result in near-normal quantitative restoration of spontaneous GH secretion, thus limiting further stimulation with the ITT to the extent that impaired GH responses can be seen even before spontaneous GH secretion starts to decline in adults. However, IGF-I status continues to provide useful information about the adequacy of the compensatory process and therefore the degree of normality of GH secretion.
Affiliation:
Department of Endocrinology, Christie Hospital, Manchester, UK.
Citation:
Cranially irradiated adult cancer survivors may have normal spontaneous GH secretion in the presence of discordant peak GH responses to stimulation tests (compensated GH deficiency). 2009, 70 (2):287-93 Clin. Endocrinol. (Oxf)
Journal:
Clinical Endocrinology
Issue Date:
Feb-2009
URI:
http://hdl.handle.net/10541/54033
DOI:
10.1111/j.1365-2265.2008.03359.x
PubMed ID:
18673465
Type:
Article
Language:
en
ISSN:
1365-2265
Appears in Collections:
All Christie Publications ; Endocrinology

Full metadata record

DC FieldValue Language
dc.contributor.authorDarzy, Ken H-
dc.contributor.authorThorner, Michael O-
dc.contributor.authorShalet, Stephen M-
dc.date.accessioned2009-03-11T09:35:06Z-
dc.date.available2009-03-11T09:35:06Z-
dc.date.issued2009-02-
dc.identifier.citationCranially irradiated adult cancer survivors may have normal spontaneous GH secretion in the presence of discordant peak GH responses to stimulation tests (compensated GH deficiency). 2009, 70 (2):287-93 Clin. Endocrinol. (Oxf)en
dc.identifier.issn1365-2265-
dc.identifier.pmid18673465-
dc.identifier.doi10.1111/j.1365-2265.2008.03359.x-
dc.identifier.urihttp://hdl.handle.net/10541/54033-
dc.description.abstractCONTEXT: We have previously demonstrated that spontaneous (physiological) GH secretion was entirely normal in cranially irradiated patients who had normal individual peak GH responses to the insulin tolerance test (ITT) but reduced maximal somatotroph reserve as indicated by substantially reduced group GH responses to the GHRH + arginine stimulation test (AST). The normality of spontaneous GH secretion was attributed to a compensatory increase in hypothalamic stimulatory input within a partially damaged hypothalamic-pituitary (h-p) axis. It is unknown, however, if such compensatory stimulation can also maintain normality of GH secretion in those who fail the ITT but pass the GHRH + AST. STUDY SUBJECTS AND DESIGN: We studied 24-h spontaneous GH secretion by 20-min sampling both in the fed state (n = 11) and in the last 24 h of a 33-h fast (n = 9) in adult cancer survivors with subnormal peak GH responses to the ITT but either normal or relatively less attenuated peak GH responses to the GHRH + AST. The study was conducted 8.3 +/- 1.8 (range 2-23) years after cranial irradiation for nonpituitary brain tumours (n = 9) or leukaemia/lymphoma (n = 2) in comparison with 30 normal controls (fasting, 14). RESULTS: Previously published diagnostic thresholds for the ITT, GHRH + AST and spontaneous GH secretion were used to characterize GH secretion. Four of the 11 patients with impaired stimulated responses to both tests showed only minor discordancies between stimulated and spontaneous GH secretion. Two of the remaining seven patients had subnormal spontaneous GH secretion. However, spontaneous GH secretion, both individually and as a group, was entirely normal in the remaining five patients who had impaired GH responses to the ITT but normal individual responses to the GHRH + AST; in these five patients, IGF-I standard deviation scores (SDS; -2.7 to -0.8) were significantly reduced to a moderate degree compared with normals. CONCLUSIONS: In cranially irradiated adult cancer survivors, it cannot be assumed that failure to pass the ITT in isolation reflects severe GH deficiency (GHD). It appears that in some patients near-maximal compensatory overdrive of the partially damaged somatotroph axis may result in near-normal quantitative restoration of spontaneous GH secretion, thus limiting further stimulation with the ITT to the extent that impaired GH responses can be seen even before spontaneous GH secretion starts to decline in adults. However, IGF-I status continues to provide useful information about the adequacy of the compensatory process and therefore the degree of normality of GH secretion.en
dc.language.isoenen
dc.subjectGrowth Hormoneen
dc.subjectAdult Canceren
dc.subjectCranial Irradiationen
dc.subjectSurvivalen
dc.subjectGHen
dc.subjectGrowth Hormone Secretionen
dc.subjectGrowth Hormone Responseen
dc.subjectGrowth Hormone Deficiencyen
dc.titleCranially irradiated adult cancer survivors may have normal spontaneous GH secretion in the presence of discordant peak GH responses to stimulation tests (compensated GH deficiency).en
dc.typeArticleen
dc.contributor.departmentDepartment of Endocrinology, Christie Hospital, Manchester, UK.en
dc.identifier.journalClinical Endocrinologyen
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