Immunofunctional assay of human growth hormone (hGH) in serum: A possible consensus for quantitative hGH measurement

Confirmation of the diagnosis of GH deficiency in adults and children involves provocative testing for human (h) GH. Different commercially available immunoassays yield largely discrepant results in the measurement of GH levels in human serum. These discrepancies result in doubtful relevance of cut-off levels proposed for GH provocative testing. We have developed an immunofunctional assay method that allows quantitation of only those GH forms in circulation that possess both binding sites of the hormone for its receptor and thus can initiate a biological signal in target cells. An anti-hGH monoclonal antibody recognizing binding site 2 of hGH is immobilized and used to capture hGH from the serum sample. Biotin-labeled recombinant GH-binding protein in a second incubation step forms a complex with those hGH molecular isoforms that have both binding sites for the receptor. The signal is detected after a short third incubation step with labeled streptavidin. The assay is sensitive (detection range, 0.1-100 micrograms/L) and has average inter- and intraassay precisions of 10.3% and 7.3% respectively. Endogenous GH-binding protein does not interfere with the hGH result; placental lactogen slows no detectable cross-reaction in this immunofunctional assay. The degree of immunofunctionally active hGH forms in serum samples, calculated by comparison of immunofunctional assay and RIA results, varied between 52-93%. We propose this immunofunctional assay for GH measurement as a new reference method for hGH quantitation in serum. The immunofunction assay translates only hGH forms into an assay signal that are capable of dimerizing GH receptors and, thus, of initiating a biological effect in target cells

Effect of Growth Hormone (hGH) Replacement Therapy on Physical Work Capacity and Cardiac and Pulmonary Function in Patients with hGH Deficiency Acquired in Adulthood.

The effects of 6 months of replacement therapy with recombinant human GH (hGH) on physical work capacity and cardiac structure and function were investigated in 20 patients with hGH deficiency of adult onset in a double blind, placebo-controlled trial. The GH dose of 12.5 micrograms/kg BW was self-administered daily sc. Oxygen consumption (VO2), CO2 production, and ventilatory volumes were measured during exercise on a bicycle spiroergometer. M-Mode echocardiography was performed using standard techniques. The VO2 max data, expressed per kg BW (mL/min.kg BW) showed a significant increase from 23.2 +/- 2.4 to 30.0 +/- 2.3 (P < 0.01) in the hGH-treated group, whereas the VO2 max data, expressed per lean body mass (milliliters per min/kg lean body mass) did not change significantly in either group. Maximal O2 pulse (milliliters per beat) increased significantly from 15.2 +/- 5.6 to 19.6 +/- 3.3 mL/beat (P < 0.01), but remained constant in the placebo group. The maximal power output (watts +/- SE) increased significantly (P < 0.01) from 192.5 +/- 13.5 to 227.5 +/- 11.5 in the hGH-treated group, but remained constant in the placebo group. Cardiac structure (left ventricular posterior wall, interventricular septum thickness, left ventricular mass, left ventricular end-systolic dimension, and left ventricular end-diastolic dimension) as well as echocardiographically assessed cardiac function did not change significantly after 6 months of treatment in either group. We conclude that hGH replacement in hGH-deficient adults improves oxygen uptake and exercise capacity. These improvements in pulmonary parameters might be due to an increase in respiratory muscle strength and partly to the changes in muscle volume per se observed during hGH replacement therapy. Furthermore, an increased cardiac output might contribute to the improvement in exercise performance during hGH treatment. According to our data, hGH replacement therapy leads to an improvement of exercise capacity and maximal oxygen uptake, but has no significant effect on cardiac structure

Growth Hormone (GH)-Releasing Peptide Stimulation of GH Release from Human Somatotroph Adenoma Cells: Interaction with GH-Releasing Hormone, Thyrotropin- Releasing Hormone, and Octreotide.

The synthetic hexapeptide GH-releasing peptide (GHRP; His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) specifically stimulates GH secretion in humans in vivo and in animals in vitro and in vivo via a still unknown receptor and mechanism. To determine the effect of GHRP on human somatotroph cells in vitro, we stimulated cell cultures derived from 12 different human somatotroph adenomas with GHRP alone and in combination with GH-releasing hormone (GHRH), TRH, and the somatostatin analog octreotide. GH secretion of all 12 adenoma cultures could be stimulated with GHRP, whereas GHRH was active only in 6 adenoma cultures. In GHRH-responsive cell cultures, simultaneous application of GHRH and GHRP had an additive effect on GH secretion. TRH stimulated GH release in 4 of 7 adenoma cultures; in TRH-responsive cell cultures there was also an additive effect of GHRP and TRH on GH secretion. In 5 of 9 adenoma cultures investigated, octreotide inhibited basal GH secretion. In these cell cultures, GHRP-induced GH release was suppressed by octreotide. In 5 of 5 cases, the protein kinase-C inhibitor phloretin partly inhibited GHRP-stimulated GH release, but not basal GH secretion. In summary, GH secretion was stimulated by GHRP in all somatotroph adenomas investigated, indicating that its unknown receptor and signaling pathway are expressed more consistently in somatotroph adenoma cells than those for GHRH, TRH, and somatostatin. Our data give further evidence that GHRP-stimulated GH secretion is mediated by a receptor different from that for GHRH or TRH, respectively, and that protein kinase-C is involved in the signal transduction pathway. Because human somatotroph adenoma cell cultures respond differently to various neuropeptides (GHRH, TRH, somatostatin, and others), they provide a model for further investigation of the mechanism of action of GHRP-induced GH secretion

Sex-specific and inter-individual differences in biomarkers of selenium status identified by a calibrated ELISA for selenoprotein P

Selenoprotein P (SELENOP) is a liver-derived transporter of selenium (Se) in blood, and a meaningful biomarker of Se status. Se is an essential trace element for the biosynthesis of enzymatically-active selenoproteins, protecting the organism from oxidative damage. The usage of uncalibrated assays hinders the comparability of SELENOP concentrations and their pathophysiological interpretation across different clinical studies. On this account, we established a new sandwich SELENOP-ELISA and calibrated against a standard reference material (SRM1950). The ELISA displays a wide working range (11.6–538.4 µg/L), high accuracy (2.9%) and good precision (9.3%). To verify whether SELENOP correlates to total Se and to SELENOP-bound Se, serum samples from healthy subjects and age-selected participants from the Berlin Aging Study II were analyzed by SELENOP-ELISA and Se quantification. SELENOP was affinity-purified and its Se content was determined from a subset of samples. There was a high correlation of total Se and SELENOP concentrations in young and elderly men, and in elderly women, but not in young women, indicating a specific sexual dimorphism in these biomarkers of Se status in young subjects. The Se content of isolated SELENOP was independent of sex and age (mean±SD: 5.4±0.5). By using this calibrated SELENOP-ELISA, prior reports on pathological SELENOP concentrations in diabetes and obesity are challenged as the reported values are outside reasonable limits. Biomarkers of Se status in clinical research need to be measured by validated assays in order to avoid erroneous data and incorrect interpretations, especially when analyzing young women. The Se content of circulating SELENOP differs between individuals and may provide some important diagnostic information on Se metabolism and status

Sex-specific and inter-individual differences in biomarkers of selenium status identified by a calibrated ELISA for selenoprotein P

Selenoprotein P (SELENOP) is a liver-derived transporter of selenium (Se) in blood, and a meaningful biomarker of Se status. Se is an essential trace element for the biosynthesis of enzymatically-active selenoproteins, protecting the organism from oxidative damage. The usage of uncalibrated assays hinders the comparability of SELENOP concentrations and their pathophysiological interpretation across different clinical studies. On this account, we established a new sandwich SELENOP-ELISA and calibrated against a standard reference material (SRM1950). The ELISA displays a wide working range (11.6–538.4 µg/L), high accuracy (2.9%) and good precision (9.3%). To verify whether SELENOP correlates to total Se and to SELENOP-bound Se, serum samples from healthy subjects and age-selected participants from the Berlin Aging Study II were analyzed by SELENOP-ELISA and Se quantification. SELENOP was affinity-purified and its Se content was determined from a subset of samples. There was a high correlation of total Se and SELENOP concentrations in young and elderly men, and in elderly women, but not in young women, indicating a specific sexual dimorphism in these biomarkers of Se status in young subjects. The Se content of isolated SELENOP was independent of sex and age (mean±SD: 5.4±0.5). By using this calibrated SELENOP-ELISA, prior reports on pathological SELENOP concentrations in diabetes and obesity are challenged as the reported values are outside reasonable limits. Biomarkers of Se status in clinical research need to be measured by validated assays in order to avoid erroneous data and incorrect interpretations, especially when analyzing young women. The Se content of circulating SELENOP differs between individuals and may provide some important diagnostic information on Se metabolism and status

Patient-reported outcomes of parenteral somatostatin analogue injections in 195 patients with acromegaly.

This work is licensed under a Creative Commons Attribution 3.0 Unported LicenseBACKGROUND: Long-acting somatostatin analogues delivered parenterally are the most widely used medical treatment in acromegaly. This patient-reported outcomes survey was designed to assess the impact of chronic injections on subjects with acromegaly. METHODS: The survey was conducted in nine pituitary centres in Germany, UK and The Netherlands. The questionnaire was developed by endocrinologists and covered aspects of acromegaly symptoms, injection-related manifestations, emotional and daily life impact, treatment satisfaction and unmet medical needs. RESULTS: In total, 195 patients participated, of which 112 (57%) were on octreotide (Sandostatin LAR) and 83 (43%) on lanreotide (Somatuline Depot). The majority (>70%) of patients reported acromegaly symptoms despite treatment. A total of 52% of patients reported that their symptoms worsen towards the end of the dosing interval. Administration site pain lasting up to a week following injection was the most frequently reported injection-related symptom (70% of patients). Other injection site reactions included nodules (38%), swelling (28%), bruising (16%), scar tissue (8%) and inflammation (7%). Injection burden was similar between octreotide and lanreotide. Only a minority of patients received injections at home (17%) and 5% were self-injecting. Over a third of patients indicated a feeling of loss of independence due to the injections, and 16% reported repeated work loss days. Despite the physical, emotional and daily life impact of injections, patients were satisfied with their treatment, yet reported that modifications that would offer major improvement over current care would be 'avoiding injections' and 'better symptom control'. CONCLUSION: Lifelong injections of long-acting somatostatin analogues have significant burden on the functioning, well-being and daily lives of patients with acromegaly.Chiasma, Inc. 60 Welles Ave, Newton, MA 02 459, USA

Investigating significant health trends in growth hormone treatments registry: rationale, aims and design of a nationwide prospective registry (study protocol)

Background Somatropin treatment is indicated in a variety of disorders including growth hormone (GH) deficiency, Prader-Willi and Turner syndrome, chronic renal insufficiency and others. To date, almost all studies have been limited to single GH products, and no independent registry across indications and somatropin products was ever established.Aim The present investigator-initiated registry named INSIGHTS-GHT aims to provide comprehensive information on various aspects of somatropin treatment in Germany in approved indications within routine clinical practice: drug utilization, effectiveness (including real final height, body composition), tolerability, quality of life, other patient related outcomes (PRO), and health economic variables.Methods Registry (prospective observational study) in specialised pediatric and adult endocrinology centres in Germany. Patients of any age are eligible for documentation, if they are on ongoing or newly initiated treatment with any approved somatropin or somatropin-related product within the labelling, available for long term follow-up documentation, and if they provided informed consent. Subjects may switch, discontinue/interrupt or initiate somatropin products at any time. They are followed up for at least 3 years (minimal study duration). Documentation is planned once or twice per year to record somatropin utilisation (product, dosing), other medications, laboratory status (glucose, lipids, GH function including stimulation tests, IGF-I, IGFBP3), if applicable, pubertal development, auxological parameters, body composition and bone age. Patient reported outcome (PRO) measures include, but are not limited to, Short Form 12 in adults and adolescents aged 14 years and over. Safety reporting includes adverse events.Conclusions The registry documents children and adults in one joint registry, includes, at present, patients in Germany and allows documentation of patients on all approved somatropin and other growth hormone preparations. It will allow to describe the transition of subjects from adolescence to adulthood (treatment and height), to describe switches between somatotropin preparations, to perform responder analyses, and to analyse differences and similarities of somatropin utilization (by age group, sex, setting, and PRO instrument). INSIGHTS-GHT offers a broad, comprehensive research platform to assess multiple relevant aspects of somatropin treatment and outcomes (including the transition of subjects from adolescence to adulthood), allows the documentation of all GH products including long-acting GH preparations after their introduction, and will evaluate the data independently of funders.Trial registration BfArM Nr. NIS7492, DRKS registry DRKS00027394

Investigating significant health trends in growth hormone treatments registry: rationale, aims and design of a nationwide prospective registry (study protocol)

Background Somatropin treatment is indicated in a variety of disorders including growth hormone (GH) deficiency, Prader–Willi and Turner syndrome, chronic renal insufficiency and others. To date, almost all studies have been limited to single GH products, and no independent registry across indications and somatropin products was ever established. Aim The present investigator-initiated registry named INSIGHTS-GHT aims to provide comprehensive information on various aspects of somatropin treatment in Germany in approved indications within routine clinical practice: drug utilization, effectiveness (including real final height, body composition), tolerability, quality of life, other patient related outcomes (PRO), and health economic variables. Methods Registry (prospective observational study) in specialised pediatric and adult endocrinology centres in Germany. Patients of any age are eligible for documentation, if they are on ongoing or newly initiated treatment with any approved somatropin or somatropin-related product within the labelling, available for long term follow-up documentation, and if they provided informed consent. Subjects may switch, discontinue/interrupt or initiate somatropin products at any time. They are followed up for at least 3 years (minimal study duration). Documentation is planned once or twice per year to record somatropin utilisation (product, dosing), other medications, laboratory status (glucose, lipids, GH function including stimulation tests, IGF-I, IGFBP3), if applicable, pubertal development, auxological parameters, body composition and bone age. Patient reported outcome (PRO) measures include, but are not limited to, Short Form 12 in adults and adolescents aged 14 years and over. Safety reporting includes adverse events. Conclusions The registry documents children and adults in one joint registry, includes, at present, patients in Germany and allows documentation of patients on all approved somatropin and other growth hormone preparations. It will allow to describe the transition of subjects from adolescence to adulthood (treatment and height), to describe switches between somatotropin preparations, to perform responder analyses, and to analyse differences and similarities of somatropin utilization (by age group, sex, setting, and PRO instrument). INSIGHTS-GHT offers a broad, comprehensive research platform to assess multiple relevant aspects of somatropin treatment and outcomes (including the transition of subjects from adolescence to adulthood), allows the documentation of all GH products including long-acting GH preparations after their introduction, and will evaluate the data independently of funders. Trial registration BfArM Nr. NIS7492, DRKS registry DRKS00027394.Open Access funding enabled and organized by Projekt DEAL.Sandoz http://dx.doi.org/10.13039/100011218Charité - Universitätsmedizin Berlin (3093