scholarly journals Determination of Free Growth Hormone

2008 ◽  
Vol 93 (8) ◽  
pp. 3008-3014 ◽  
Author(s):  
Jan Frystyk ◽  
Caroline Marie Andreasen ◽  
Sanne Fisker
Keyword(s):  
Growth Hormone ◽  
Area Under The Curve ◽  
Tolerance Test ◽  
Insulin Tolerance Test ◽  
Clinical Use ◽  
Serum Free ◽  
High Affinity ◽  
Insulin Tolerance ◽  
Free Growth

Abstract Context: Approximately 50% of circulating GH is bound to the high-affinity GH-binding protein (GHBP), which is known to affect the pharmacokinetics, bioactivity, and quantitative determination of GH. Nevertheless, the presence of GHBP is rarely taken into account in the clinical use of GH measurements. Objective: Our objective was to develop an assay for free GH in serum. Methods: We used ultrafiltration by centrifugation. Due to the small molecular difference between GH and GHBP, the size of GHBP and GHBP-GH complexes was increased by preincubation of serum with a monoclonal GHBP antibody (MAb 263). Results: The ultrafiltration membrane almost completely retained all GHBP (>98.5%) and allowed free passage of unbound GH (>98.4%). Addition of increasing concentrations of GHBP reduced free GH dose dependently, and measured and calculated levels of free GH changed in parallel. During an insulin-tolerance test, free and total GH changed in parallel in all individuals (n = 11) and their peak values as well as area under the curve values were positively correlated (r = 0.89; P < 0.001 and r = 0.92; P < 0.001, respectively). Of note, the relative levels of free GH (calculated as the area under the curve of free to total GH) was inversely correlated with GHBP (r = −0.94; P < 0.001). Conclusion: It is possible to measure free GH in human serum. Free GH correlated positively with total GH and inversely with GHBP. Measurement of free GH may be a helpful future tool in the management of GH disorders and in studies of GH-GHBP interrelationships.

Growth hormone (GH) release after administration of GH-releasing hormone in relation to endogenous 24-h GH secretion in short children

1989 ◽  
Vol 122 (1) ◽  
pp. 61-68 ◽  
Author(s):  
L. Gelander ◽  
K. Albertsson-Wikland
Keyword(s):  
Growth Hormone ◽  
Area Under The Curve ◽  
Tolerance Test ◽  
Insulin Tolerance Test ◽  
High Variability ◽  
Releasing Hormone ◽  
Gh Secretion ◽  
Insulin Tolerance ◽  
Short Children ◽  
Ghrh Test

ABSTRACT Endogenous GH secretion was measured every 20 min for 24 h in 36 short children. This was immediately followed by an i.v. injection of GH-releasing hormone (GHRH)(1–29)-NH2 (1 μg/kg), and GH was estimated every 15 min for the following 2 h. The aim was to determine whether endogenous pulsatile GH secretion had any relation to, or influence on, the GH release induced by GHRH. A high variability was found both in the 24-h GH secretion expressed as area under the curve above the baseline (0–1588 mU/l × 24 h) and the maximal GH response to GHRH (5–296 mU/l), as well as after an arginine–insulin tolerance test (4–59 mU/l). We found a positive correlation (correlation coefficient of Spearman (rs) = 0·49; P < 0·01) between the GH response to GHRH and the spontaneous GH secretion over a 24-h period, in spite of a negative correlation (rs = −0·80; P < 0·01) with the GH secretion during the preceeding 3 h. We conclude that the GH response to a GHRH test correlates with endogenous GH secretion in short children, and may be helpful in estimating the ability to release GH. It is important, however, to be aware of the influence of the spontaneous GH secretion during the 3 h immediately preceeding administration of GHRH. Journal of Endocrinology (1989) 122, 61–68

ENDOCRINE DISTURBANCES IN PATIENTS WITH CONGENITAL AQUEDUCTAL STENOSIS

1975 ◽  
Vol 80 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Robert Fiedler ◽  
Dorothy T. Krieger
Keyword(s):  
Present Report ◽  
Aqueductal Stenosis ◽  
Tolerance Test ◽  
Insulin Tolerance Test ◽  
Endocrine Function ◽  
Insulin Tolerance ◽  
Endocrine Disturbances ◽  
Reversible Lesion ◽  
Hormone Responses

ABSTRACT Congenital stenosis of the aqueduct of Sylvius is reported to be associated with sella turcia enlargement and clinical and laboratory abnormalities of the hypothalamic-pituitary-target-organ axis. It is a surgically reversible lesion. In the present report, 3 female patients with this lesion were studied with tests of basal endocrine function, as well as insulin tolerance tests, response to metyrapone and determination of circadian periodicity of plasma cortisol levels. In one patient all testing was normal and no surgery was performed. In 2 other patients the insulin tolerance test revealed either abnormal cortisol or growth hormone responses and in one patient urinary gonadotrophins were absent. All tests became normal post-operatively although in one instance not completely so until 5 years after surgery.

scholarly journals Clinical Evaluation of Growth Hormone Secretion in Cattle Using Insulin Tolerance Test

2003 ◽  
Vol 65 (7) ◽  
pp. 809-812
Author(s):  
Masafumi OGURO ◽  
Hirotaka ISHIKAWA ◽  
Hiromichi OHTSUKA ◽  
Fumio HOSHI ◽  
Seiichi KAWAMURA
Keyword(s):  
Growth Hormone ◽  
Clinical Evaluation ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Tolerance Test ◽  
Insulin Tolerance Test ◽  
Insulin Tolerance

Test of growth hormone secretion in adults: poor reproducibility of the insulin tolerance test

1995 ◽  
Vol 133 (3) ◽  
pp. 305-312 ◽  
Author(s):  
Hans C Hoeck ◽  
Peter Vestergaard ◽  
Poul E Jakobsen ◽  
Peter Laurberg
Keyword(s):  
Growth Hormone ◽  
Gh Deficiency ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Tolerance Test ◽  
Insulin Tolerance Test ◽  
Repeated Testing ◽  
Provocative Test ◽  
Insulin Tolerance ◽  
Gh Deficiency In Adults

Hoeck HC, Vestergaard P, Jakobsen PE, Laurberg P, Test of growth hormone secretion in adults: poor reproducibility of the insulin tolerance test. Eur J Endocrinol 1995;133:305–12. ISSN 0804–4643 The insulin tolerance test (ITT) is regarded as the most reliable provocative test in the diagnosis of growth hormone (GH) deficiency in adults. In the present study the test was evaluated by investigating the range of GH responses in normal adult males and females and the intra-individual reproducibility of the test. Sixteen healthy non-obese adults, eight males (median age 31.5 years) and eight females (median age 31.8 years) were tested twice with the ITT, with a minimum of 72 h between each test. The females were tested between day 3 and day 10 of their menstrual cycles. Adequate hypoglycemia was achieved in all cases with a median nadir blood glucose of 1.3 mmol/l (range 0.8–2.0). Growth hormone in serum was measured by immunoradiometric assay and low values were confirmed by a different assay. Median peak GH concentration responses to the ITT were: in males 27.9 μg/l, range 5.0–71.1 (test 1) and 30.5 μg/l, range 7.9–69.5 (test 2); and in females 9.0 μg/l, range 4.1–17.9 (test 1) and 8.4 μg/l, range 0.09–42.4 (test 2). The rise in GH concentration during the ITT was higher in males than in females. In the males, all stimulated GH values were ≥5.0 μg/l. In the females, four out of 16 tests gave values below 5.0 μg/l and in one test the GH value was around the detection limit of the assays. There was poor reproducibility during repeated testing, with no correlation between the results of the two tests. The results did not correlate to the magnitude of the hypoglycemia. The results of this study illustrate the complexity of the regulation of GH secretion and indicate that the ITT is less useful for diagnosing GH deficiency in adults than previously anticipated. The diagnosis of GH deficiency in adults and especially in adult females should not be based on the results of a single ITT alone. Hans C Hoeck, Department of Endocrinology, Aalborg Regional Hospital, Reberbansgade, DK-9000 Aalborg, Denmark

RADIOIMMUNOASSAY OF GROWTH HORMONE IN HUMAN PLASMA

1972 ◽  
Vol 71 (4) ◽  
pp. 649-664 ◽  
Author(s):  
Kristian F. Hanssen
Keyword(s):  
Growth Hormone ◽  
Human Plasma ◽  
Coefficient Of Variation ◽  
Degradation Products ◽  
Peak Plasma ◽  
Gel Filtration ◽  
Tolerance Test ◽  
Precipitation Reaction ◽  
Insulin Tolerance

ABSTRACT The double antibody radio-immunoassay (pre-precipitation technique) for immunoreactive growth hormone (IRHGH) in human plasma has been evaluated on the basis of dilution and recovery experiments as well as by the investigation of accuracy and reproducibility. Given optimal conditions for the precipitation reaction, the method seems suitable for determination of plasma IRHGH. No cross-reaction between the precipitating antiserum and human gammaglobulin was demonstrated. Furthermore, by using an incubation period of 6 days for the reaction between 125I-HGH and the precipitated HGH antibodies, no serum factor influencing this reaction could be demonstrated. The results of the plasma IRHGH determinations were shown to be independent of the percentage of the radioactive degradation products present in the tracer HGH. The lower detection limit is better than 0.39 ng/ml. The cumulated within-assay coefficient of variation was between 4–7% and the cumulated between-assay coefficient of variation 10%. By using gel filtration, IRHGH in the plasma was shown to be nonhomogeneous when considering molecular weight. The normal fasting values in the ambulatory state was (Mean ± sd) ng/ml: Men 1.48 ± 0.33; women 3.83 ± 3.47. During the insulin tolerance test the mean peak plasma IRHGH was lower in children than in adults (0.02 > P > 0.01). It is suggested that this is due to the influence of sex steroids in adult subjects.

Comparison of pituitary–adrenal responsiveness between insulin tolerance test and growth hormone-releasing peptide-2 test: A pilot study

Peptides ◽  
2010 ◽  
Vol 31 (4) ◽  
pp. 657-661 ◽  
Author(s):  
Toshiko Kano ◽  
Hitoshi Sugihara ◽  
Mariko Sudo ◽  
Mototsugu Nagao ◽  
Taro Harada ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Pilot Study ◽  
Tolerance Test ◽  
Insulin Tolerance Test ◽  
Insulin Tolerance

scholarly journals Diagnostic Usefulness of the Growth Hormone-Releasing Peptide-2 Test as a Substitute for the Insulin Tolerance Test in Hypopituitarism

2008 ◽  
Vol 55 (4) ◽  
pp. 777-783 ◽  
Author(s):  
Kazunori KAGEYAMA ◽  
Takeshi NIGAWARA ◽  
Satoru SAKIHARA ◽  
Shinobu TAKAYASU ◽  
Ken TERUI ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Tolerance Test ◽  
Insulin Tolerance Test ◽  
Insulin Tolerance ◽  
Diagnostic Usefulness
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