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.

scholarly journals 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

2005 ◽  
Vol 153 (4) ◽  
pp. 521-526 ◽  
Author(s):  
K Borm ◽  
M Slawik ◽  
F Beuschlein ◽  
L Seiler ◽  
F Flohr ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Pilot Study ◽  
Low Dose ◽  
Peak Plasma ◽  
Isotonic Saline ◽  
Serum Cortisol ◽  
Tolerance Test ◽  
Serum Glucose ◽  
Glucose Infusion ◽  
Insulin Tolerance

Objective: The insulin tolerance test (ITT) is regarded as the gold standard for the evaluation of pituitary ACTH and growth hormone reserve. However, the intended critical hypoglycemia results in considerable discomfort and requires close surveillance during the test. Design and methods: In a pilot study, we evaluated whether the ITT could be markedly simplified, made less hazardous and more convenient by routine i.v. low-dose glucose administration after hypoglycemia has been achieved. Sixteen healthy subjects (three females, 13 males) were tested twice in a randomized, single-blinded fashion, receiving 0.15 IU insulin/kg body weight as an i.v. bolus. After hypoglycemia (serum glucose less than 2.2 mmol/l) had been achieved, 500 ml isotonic saline (protocol A (A)), or 500 ml 5% glucose solution (protocol B (B)) were infused over 30 min. Results: Compared with saline, glucose infusion shortened the period of hypoglycemia from 31 + 14 to 17 + 6 min (P < 0.01). In addition, prolonged duration of hypoglycemia (>45 min) was reduced (6 subjects in protocol A vs none in protocol B). Despite shorter duration of hypoglycemia, all subjects had adequate stimulated cortisol (>500 nmol/l) and hGH (>5 μg/l) levels. Mean peak concentrations of plasma ACTH (24 ± 12 pmol/l (A) vs 21 ± 8 pmol/l (B)), serum cortisol (690 ± 83 nmol/l vs 634 ± 83 nmol/l) and serum hGH (26 ± 16 μg/l vs 22 ± 13 μg/l) were slightly, but not significantly lower. In contrast, glucose infusion significantly reduced peak plasma epinephrine levels at 45 min (4.96 ± 4.91 pmol/l (A) vs 1.53 ± 1.1 pmol/l (B), P < 0.05) and ameliorated discomfort, as evaluated by a visual analog scale (P < 0.05). Conclusions: Taken together, our pilot study suggests that, while the duration of hypoglycemia is shortened and acute epinephrine response is reduced, low-dose infusion of glucose does not significantly alter peak cortisol and growth hormone responses during ITT. Studies with a larger number of subjects and patients with suspected hypopituitarism are needed to further evaluate this modified protocol.

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 (&gt;98.5%) and allowed free passage of unbound GH (&gt;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 &lt; 0.001 and r = 0.92; P &lt; 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 &lt; 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.

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.

IMMUNOREACTIVE GROWTH HORMONE IN HUMAN URINE

1972 ◽  
Vol 71 (4) ◽  
pp. 665-676 ◽  
Author(s):  
Kristian F. Hanssen
Keyword(s):  
Molecular Weight ◽  
Growth Hormone ◽  
Linear Relationship ◽  
Human Urine ◽  
Gel Filtration ◽  
Human Growth ◽  
Normal Subjects ◽  
Normal Human ◽  
Radio Immunoassay

ABSTRACT By using a double antibody radio-immunoassay (pre-precipitation technique) for the determination of immunoreactive human growth hormone (IRHGH) in normal human urine concentrated by dialysis and lyophilization, a factor was revealed that displaces 125I-HGH from HGH antibodies. This displacement was neither due to salts nor to glucose; it is suggested that it is due to IRHGH in the urine. A linear relationship between dilution of urine and the measured IRHGH concentration was obtained. Recovery of exogenous HGH was between 70–105%. The recovery of IRHGH from different volumes of urine following dialysis and lyophilization was between 97–110%. Plasma IRHGH and urinary IRHGH was measured simultaneously after HGH injection in a normal subject. A correlation was shown between plasma IRHGH and urinary IRHGH. In 9 normal subjects, the urinary IRHGH ranged from 28–53 ng/24 h. The excretion of urinary IRHGH was increased in acromegaly and was diminished in some, but not in all patients with adult hypopituitarism. The urinary IRHGH was further studied by gel filtration. It was recovered in one peak corresponding to a molecular weight of approximately 20 000 – 30 000. However, in the present work it was not clarified whether the urinary IRHGH represents pituitary HGH excreted in the urine or a metabolite of high molecular weight with retained immunological properties.

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

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