Determination of Free Growth Hormone

Frystyk, Jan; Andreasen, Caroline Marie; Fisker, Sanne

doi:10.1210/jc.2008-0375

Cited by 19 publications

(12 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Frystyk et al (16) speculated that GHBP may regulate GH bioactivity via an unknown mechanism. Therefore, we examined correlations between bGH, iGH, and GHBP over the course of the exercise protocol to explore whether different feedback mechanisms may play a role in differences in GH secretion.…”

Section: Discussionmentioning

confidence: 99%

Immunoreactive and bioactive growth hormone responses to resistance exercise in men who are lean or obese

Thomas

Kraemer

Kennett

et al. 2011

Journal of Applied Physiology

View full text Add to dashboard Cite

The present study was designed to examine the effects of a highvolume, whole body acute resistance exercise (RE) protocol on immunoreactive GH (iGH), bioactive GH (bGH), and GH-binding protein (GHBP) in sedentary lean and obese men. Nine obese (mean Ϯ SD: 20.8 Ϯ 2.1 yr old, 177.0 Ϯ 4.1 cm height, 108.7 Ϯ 15.9 kg body mass, 37.6 Ϯ 5.29% body fat) and nine lean (20.1 Ϯ 2.1 yr old, 177.8 Ϯ 8.7 cm height, 71.7 Ϯ 5.8 kg body mass, 14.7 Ϯ 3.54% body fat) men completed an acute RE protocol (6 exercises, 3 sets of 10 repetitions at 85-95% of 10 repetitions maximum with 120-and 90-s rest periods), and blood samples were collected before, at the midpoint, and immediately after exercise and during recovery (ϩ50, ϩ70, and ϩ110). In contrast to prior studies, which examined acute responses to cardiovascular exercise protocols, groups did not differ in iGH response to the exercise stimulus. However, bGH concentrations overall were significantly lower in the obese than the lean participants (P Ͻ 0.001). Additionally, obese individuals had significantly higher GHBP concentrations (P Ͻ 0.001). Results suggest that obese and lean sedentary men performing a high-volume, whole body acute RE protocol demonstrate similar increases in iGH. Blunted bGH and elevated GHBP concentrations are indicative of altered GH activity associated with obesity. Prior research findings of blunted iGH response may be attributable to RE protocols not equated on relative intensity or volume. These results underscore the complexity of pituitary biology and its related mechanisms and may have implications for exercise prescription in the treatment of obesity.

show abstract

Section: Discussionmentioning

confidence: 99%

Immunoreactive and bioactive growth hormone responses to resistance exercise in men who are lean or obese

Thomas

Kraemer

Kennett

et al. 2011

Journal of Applied Physiology

View full text Add to dashboard Cite

show abstract

“…GH not associated with GHBP (identical to the truncated, extracellular domain of the GHR), were determined by a novel, validated in-house ultrafiltration assay that allows separation of free from bound GH at approached in vivo-like conditions. The separation procedure was performed as described recently (18). The obtained ultrafiltrates were assayed for GH using the GH Delfia, performed according to the instructions by the manufacturer, with overall intra-and inter-assay CV values averaging 7 and 11% respectively, i.e.…”

Section: Assaysmentioning

confidence: 99%

Conventional and novel biomarkers of treatment outcome in patients with acromegaly: discordant results after somatostatin analog treatment compared with surgery

Rubeck

Madsen²,

Andreasen³

et al. 2010

European Journal of Endocrinology

Self Cite

View full text Add to dashboard Cite

Context: Control of disease activity in acromegaly is critical, but the biochemical definitions remain controversial. Objective: To compare traditional and novel biomarkers and health status in patients with acromegaly treated with either surgery alone or somatostatin analog (SA). Design and methods: Sixty-three patients in long-term remission based on normalized total IGF1 levels after surgery alone (nZ36) or SA (nZ27) were studied in a cross-sectional manner. The groups were comparable at diagnosis regarding demographic and biochemical variables. Each subject underwent 3 h of serum sampling including a 2-h oral glucose tolerance test (OGTT). Health status was measured by two questionnaires: EuroQoL and Acrostudy (Patient-assessed-Acromegaly symptom questionnaire (PASQ)). Results: Total and bioactive IGF1 (mg/l) levels were similar (total: 185G10 (SA) versus 171G8 (surgery) (PZ0.28); bioactive: 1.9G0.2 vs 1.9G0.1 (PZ0.70)). Suppression of total and free GH (mg/l) during OGTT was blunted in the SA group (total GH nadir : 0.59G0.08 (SA) versus 0.34G0.06 (surgery) (PZ0.01); free GH nadir : 0.43G0.06 vs 0.19G0.04 (P!0.01)). The insulin response to OGTT was delayed, and the 2-h glucose level was elevated during SA treatment (PZ0.02). Disease-specific health status was better in patients after surgery (PZ0.02). Conclusions: i) Despite similar and normalized IGF1 levels, SA treatment compared with surgery alone was associated with less suppressed GH levels and less symptom relief; ii) this discordance may be due to specific suppression of hepatic IGF1 production by SA; iii) we suggest that biochemical assessment during SA treatment should include both GH and IGF1.

show abstract

“…When estimating free GH using ultrafiltration by centrifugation to retain GHBP, Frystyk et al (29) found a positive correlation between total and free GH and an inverse relation between free GH and GHBP. In our study population, GHBP levels remained unchanged whereas GH increased significantly.…”

Section: Discussionmentioning

confidence: 99%

Adaptation of ghrelin and the GH/IGF axis to high altitude

Riedl

Kluge²,

Schweitzer³

et al. 2012

European Journal of Endocrinology

View full text Add to dashboard Cite

Objective: High altitude (HA) provokes a variety of endocrine adaptive processes. We investigated the impact of HA on ghrelin levels and the GH/IGF axis. Design: Observational study as part of a medical multidisciplinary project in a mountainous environment. Methods: Thirty-three probands (12 females) were investigated at three timepoints during ascent to HA (A: d K42, 120 m; B: d C4, 3440 m; C: d C14, 5050 m). The following parameters were obtained: ghrelin; GH; GH-binding protein (GHBP); IGF1; IGF2; IGF-binding proteins (IGFBPs) -1, -2, and -3; acid-labile subunit (ALS); and insulin. Weight was monitored and general well being assessed using the Lake Louise acute mountain sickness (AMS) score. Results: Ghrelin (150 vs 111 pg/ml; P!0.01) and GH (3.4 vs 1.7 mg/l; P!0.01) were significantly higher at timepoint C compared with A whereas GHBP, IGF1, IGF2, IGFBP3, ALS, and insulin levels did not change. IGFBP1 (58 vs 47 mg/l; P!0.05) and, even more pronounced, IGFBP2 (1141 vs 615 mg/l; P!0.001) increased significantly. No correlation, neither sex-specific nor in the total group, between individual weight loss (females: K2.1 kg; males: K5.1 kg) and rise in ghrelin was found. Five of the subjects did not reach investigation point C due to AMS. Conclusions: After 14 days of exposure to HA, we observed a significant ghrelin and GH increase without changes in GHBP, IGF1, IGF2, IGFBP3, ALS, and insulin. Higher GH seems to be needed for acute metabolic effects rather than IGF/IGFBP3 generation. Increased IGFBP1 and -2 may reflect effects from HA on IGF bioavailability. European Journal of Endocrinology 166 969-976

show abstract

Determination of Free Growth Hormone

Abstract: 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.

Cited by 19 publications

References 26 publications

Immunoreactive and bioactive growth hormone responses to resistance exercise in men who are lean or obese

Immunoreactive and bioactive growth hormone responses to resistance exercise in men who are lean or obese

Conventional and novel biomarkers of treatment outcome in patients with acromegaly: discordant results after somatostatin analog treatment compared with surgery

Adaptation of ghrelin and the GH/IGF axis to high altitude

Contact Info

Product

Resources

About