This Article Full Text Full Text (PDF) Submit a related Letter to the Editor Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hoeck, H. C. Articles by Laurberg, P. Search for Related Content PubMed PubMed Citation Articles by Hoeck, H. C. Articles by Laurberg, P.

Diagnosis of Growth Hormone (GH) Deficiency in Adults with Hypothalamic-Pituitary Disorders: Comparison of Test Results Using Pyridostigmine Plus GH-Releasing Hormone (GHRH), Clonidine Plus GHRH, and Insulin-Induced Hypoglycemia as GH Secretagogues¹

Department of Endocrinology and Medicine, Aalborg Hospital, DK-9000 Aalborg, Denmark

Address all correspondence and requests for reprints to: Hans C. Hoeck, M.D., Ph.D., Department of Endocrinology and Medicine, Aalborg Hospital, Reberbansgade, DK-9000 Aalborg, Denmark. E-mail: hans.chr.hoeck{at}dadlnet.dk

The insulin tolerance test (ITT) is widely accepted as the method of choice to evaluate GH secretion capacity in adults with hypothalamic-pituitary disorders. However, the test is not suitable in the elderly or in patients with cardiovascular disease or seizure disorders. In recent years alternatives to the ITT have been introduced. The purpose of the present study was to investigate the diagnostic outcome with the ITT, the pyridostigmine plus GHRH (PD+GHRH) test, the clonidine plus GHRH (CLO+GHRH) test, and insulin-like growth factor I (IGF-I) in an unselected group of patients with hypothalamic-pituitary disease. An evaluation of the reproducibility of the different stimulation tests was included in the study. Based on repeated testing with the various GH stimulation tests in healthy adult males and females, the lower limits of normality for the ITT, the PD+GHRH test, and the CLO+GHRH test were 3.92, 12.8, and 19.0 µg/L, respectively. A consecutive group of 26 unselected patients with hypothalamic-pituitary disorders, 13 males and 13 females (median age, 44 ys), were tested twice with all stimulation tests, except that only 10 patients were tested once with the CLO+GHRH test due to side-effects related to clonidine. The peak GH responses between test 1 and test 2 correlated significantly in both the ITT and the PD+GHRH test (P < 0.02), and no significant difference was observed in the median peak response to repeated testing. In addition, no sex difference was observed. The coefficients of variation (CV) were 96% (ITT) and 45% (PD+GHRH), but in the majority of patients low values were repeatedly low. The peak GH response was significantly higher during the PD+GHRH test than during the ITT (P = 0.008). In the 10 patients tested with the PD+GHRH and CLO+GHRH tests there was no significant difference in the peak GH response (P = 0.398). When the test specific cut-off values were used, no significant difference in diagnostic outcome was observed between the various tests (P > 0.3). In contrast, the diagnosis obtained with IGF-I differed significantly from all GH stimulation tests (P < 0.03). Twenty (77%) and 22 (85%) patients were diagnosed to be GH deficient with the ITT and the PD+GHRH test, respectively. Of the 14 patients with multiple pituitary failure (>2 hormones affected), GH deficiency was present in more than 90% regardless of the type of stimulation test used. The IGF-I levels were only subnormal in 42% of the patients and did not correlate with the peak GH responses in any of the stimulation tests (P > 0.05). Except for 1 patient all patients with subnormal IGF-I were GH deficient in all stimulation tests. It is concluded that in patients with hypothalamic-pituitary disease and a normal IGF-I level 2 stimulation tests should be performed to establish a diagnosis of GH deficiency. In patients with a subnormal IGF-I value a single GH stimulation test should be sufficient to confirm the presence of GH deficiency.

This article has been cited by other articles:

				S. Zucchini, P. Pirazzoli, F. Baronio, M. Gennari, M. O. Bal, A. Balsamo, S. Gualandi, and A. Cicognani Effect on Adult Height of Pubertal Growth Hormone Retesting and Withdrawal of Therapy in Patients with Previously Diagnosed Growth Hormone Deficiency J. Clin. Endocrinol. Metab., November 1, 2006; 91(11): 4271 - 4276. [Abstract] [Full Text] [PDF]

				K Borm, M Slawik, F Beuschlein, L Seiler, F Flohr, A Berg, A Koenig, and M Reincke Low-dose glucose infusion after achieving critical hypoglycemia during insulin tolerance testing: effects on time of hypoglycemia, neuroendocrine stress response and patient's discomfort in a pilot study Eur. J. Endocrinol., October 1, 2005; 153(4): 521 - 526. [Abstract] [Full Text] [PDF]

				M. Maghnie, G. Aimaretti, S. Bellone, G. Bona, J. Bellone, R. Baldelli, C. de Sanctis, L. Gargantini, R. Gastaldi, L. Ghizzoni, et al. Diagnosis of GH deficiency in the transition period: accuracy of insulin tolerance test and insulin-like growth factor-I measurement Eur. J. Endocrinol., April 1, 2005; 152(4): 589 - 596. [Abstract] [Full Text] [PDF]

				B. M. K. Biller, M. H. Samuels, A. Zagar, D. M. Cook, B. M. Arafah, V. Bonert, S. Stavrou, D. L. Kleinberg, J. J. Chipman, and M. L. Hartman Sensitivity and Specificity of Six Tests for the Diagnosis of Adult GH Deficiency J. Clin. Endocrinol. Metab., May 1, 2002; 87(5): 2067 - 2079. [Abstract] [Full Text] [PDF]

				M. E. Molitch Diagnosis of GH Deficiency in Adults--How Good Do the Criteria Need to Be? J. Clin. Endocrinol. Metab., February 1, 2002; 87(2): 473 - 476. [Full Text] [PDF]

				C. A. Jaffe, W. Pan, M. B. Brown, R. DeMott-Friberg, and A. L. Barkan Regulation of GH Secretion in Acromegaly: Reproducibility of Daily GH Profiles and Attenuated Negative Feedback by IGF-I J. Clin. Endocrinol. Metab., September 1, 2001; 86(9): 4364 - 4370. [Abstract] [Full Text] [PDF]