Gh-rh stimulation test

BACKGROUND: End-stage renal failure (ESRF) patients demonstrate augmented growth hormone (GH) secretion, but normal insulin-like growth factor-I (IGF-I) concentrations, indicating a state of GH resistance. To test this hypothesis, we compared the IGF-I response with exogenous GH in haemodialysis patients and healthy controls, with special focus on free GH and bioactive IGF-I. METHODS: Ultrafiltered free GH and total GH were measured in serum collected hourly for 24 h at baseline and after 7 days of recombinant human (rh) GH (50 µg/kg/day) treatment in 11 non-diabetic haemodialysis patients and 10 matched controls...

In patients with b-thalassemia major (TM), the anterior pituitary gland is particularly sensitive to free radical stresses. It has been reported that the GH deficiency (GHD) may be secondary to either pituitary or hypothalamic dysfunction. The duration of the disease, the patient's age and the severity of iron overload are the most important factors responsible for the defect of growth hormone (GH) secretion. Recent reports have documented a frequency of severe growth hormone deficiency in 13%-32% of patients with b-thalassemia major...

GH secretion is mainly regulated at the hypothalamus by a dual interplay between growth hormone releasing hormone (GHRH) and somatostatin, which are modulated by various factors. We examined the regulatory mechanism of GH secretion in an apparently healthy young man without decreased IGF-1 concentration and nocturnal GH secretion, but who showed low responses to insulin tolerance (ITT) and to GHRP-2 tests. The patient also had no GH response to acute aerobic exercise. However, he had normal secretion of pituitary hormone based on hypothalamic releasing hormone tests combined with CRH, GRH as GHRH, LH-RH and TRH...

A 54-year-old man with type 2 diabetes was referred to our hospital for endocrine evaluation of acromegaly. Physical examination showed typical acromegalic features without Cushingoid features. Magnetic resonance imaging of the brain revealed the presence of a pituitary macroadenoma. Basal plasma levels of GH and insulin-like growth factor-I under fasting hyperglycemia (202 mg/dl) were markedly elevated. Plasma GH levels paradoxically increased after stimulation with TRH and LH-RH, and decreased after bromocriptine and octreotide administration...

The basic mechanisms that drive the renewal of GH pulses in the human are not understood. Recent ensemble models predict that pulse regeneration requires quenching of an ongoing GH pulse by somatostatin outflow and evocation of a new burst by rebound GHRH release. We reasoned that related principles might explain why women consistently maintain higher-amplitude GH secretory bursts than men. Accordingly, the present study tests the hypothesis that gender modulates the successive dynamics of GH feedback and escape in the morning fasting, when GH pulses are larger in women...

Renal disease in children disrupts the growth hormone (GH) and insulin-like growth factor (IGF) axis and causes growth failure. Although GH therapy stimulates growth in these children, their short stature is likely due to a form of IGF-1 deficiency (IGFD) rather than GH deficiency. Recent experimental data have caused us to reconsider the importance of IGF-1 and IGFD to human growth. Pharmacology studies in rodents, as well as studies in patients with no functional GH receptors and primary IGFD, have shown that IGF-1 is an effective growth-promoting therapy...

The primary cause of waning GH and IGF-I concentrations in healthy aging adults is not established. To test the postulate that age influences negative feedback by IGF-I in a secretagogue-specific fashion, 17 normal men (nine young and eight older) each completed eight randomly ordered injections of placebo or recombinant human (rh) IGF-I (20 microg/kg sc), followed by saline/rest, aerobic exercise, GHRH (1 microg/kg iv bolus), or GH-releasing peptide-2 (1 microg/kg iv bolus) stimulation. GH secretion was monitored by sampling blood every 10 min for 7 h, high-sensitivity immunochemiluminometric assay, and deconvolution analysis conditioned on prior pulse-onset times and biexponential kinetics...

The present study tests the mechanistic postulate that estrogen confers resistance to negative feedback by systemic IGF-I. To this end, eight postmenopausal women received a constant iv infusion of recombinant human (rh)IGF-I (10 micro g/kg.h x 6 h) and saline in randomized order on the 10th day of supplementation with oral estradiol (E(2)) and placebo (Pl). GH secretion was quantitated by 10-min blood sampling, immunochemiluminometry assay, and deconvolution analysis. Administration of E(2) compared with Pl followed by saline infusion: 1) stimulated pulsatile GH secretion ( micro g/liter...

The present study tests the postulate that testosterone (Te) stimulates GH secretion, in part, by attenuating autonegative feedback. To this end, 13 healthy men (ages 43-71 yr) received three consecutive weekly im injections of placebo (Pl) (n = 7) or Te (200 mg) (n = 6) in a prospectively randomized, double-blind, parallel-cohort design. An iv pulse of saline or recombinant human (rh)GH (3 micro g/kg.6 min) was infused 2 h before bolus saline or GH-releasing peptide (GHRP)-2 (1 micro g/kg) in the fasting state...

OBJECTIVE: Gonadal dysfunction has been recognized for a long time in uremic male patients. The present study assesses the hypothalamo-pituitary-testicular axis and growth hormone status in male continuous ambulatory peritoneal dialysis (CAPD) patients, before and after recombinant human erythropoietin (rHuEPO) therapy. DESIGN: Single-center prospective study. SUBJECTS: Ten anemic male patients with chronic renal insufficiency, and 11 healthy volunteers with normal renal function, matched for age, were included in the study...

Increased circulating growth hormone (GH) levels and aberrant response to different stimuli characterize both type 1 diabetes mellitus and chronic uremia and are associated with severe retinal, kidney and heart complications. Combined kidney and pancreas transplantation is a therapy that restores the endogenous, closed-loop, insulin secretion in diabetes and cure uremia. To evaluate if combined transplantation can restore a normal secretion and response of GH to growth hormone releasing hormone (GH-RH), we studied four groups of subjects: (1) seven type 1 diabetic patients with end-stage renal failure who had received pancreas and kidney transplantation (KPTx); (2) six diabetic uremic subjects, candidates for combined transplantation (IDDUP); (3) nine patients with chronic uveitis on immunosuppressive therapy comparable to pancreas recipients, six of whom treated only with prednisone (UVEST), while three (4) were treated with both prednisone and cyclosporin (UVESTCY)...

OBJECTIVE: Inhibin B is a secretory product of Sertoli cells of the human testis. It has been reported that serum levels of inhibin B in infant boys, peaking at 3 months of age, exceed levels in adult men. The aim of this study was to evaluate inhibin B secretion in primary prepubertal mixed testicular cell cultures, prepared from testes collected at necropsy. DESIGN AND METHODS: Cell cultures were divided into three age groups on the basis of differences in testicular histology: group 1 (n = 7), 1- to 10-day-old newborns, group 2 (n = 7), 1- to 9-month-old infants, and group 3 (n = 8), 12- to 84-month-old children...

The aim of this study was to assess the GH-IGFI axis, GH receptor availability, as reflected by the levels of GH-BP, and the amount of GH-dependent IGFBP-3 in adult IDDM patients with different degrees of metabolic control. Thus, 10 adult well-controlled IDDMs (HbA1 7.8 +/- 0.4%), 10 adult non-ketotic poorly controlled IDDMs (HbA1 13.3 +/- 7%) and 14 sex- and age-matched healthy controls were subjected to two intravenous GH-RH stimulation tests with 0.1 and 1.0 microg/kg body weight respectively, and a plasma IGF-1 generation test induced by the administration of hGH...

OBJECTIVE: Growth retardation is a prominent secondary feature of chronic liver disease. We investigated the hypothalamic-pituitary-liver axis in six patients with inherited liver disease and growth failure. The objectives were to determine (1) whether there were any abnormalities in the GH/IGF-I/IGFBPs/GH binding protein (GHBP) axis, (2) whether any abnormalities were nutrition-dependent, and (3) whether recombinant human (rh) GH could be efficaciously and safely administered. MEASUREMENTS: The evaluation included two standard GH provocative tests, GHRH test, night-time GH secretion, GHBP; and IGF-I, IGFBP-3 and IGFBP-1 before and after 0...

To evaluate the metabolic effects of long-term treatment with recombinant human (rh) GH in short children with chronic renal failure (CRF), annual oral glucose tolerance tests (oGTT) during rhGH therapy for up to 5 y in 53 prepubertal children with CRF on conservative treatment, dialysis, and after renal transplantation were compared with that of 12 age-matched children treated with rhGH for idiopathic short stature. At the start of rhGH treatment, fasting values of glucose, insulin, glycosylated Hb A (HbA1C), triglycerides, cholesterol, glucose, and insulin responses during oGTT were significantly elevated in all patient groups compared with control subjects (p < 0...

OBJECTIVE: Since hormonal replacement therapy (HRT) affects plasma GH levels, the present study aimed to verify the effect of tibolone, a synthetic steroid, on modulating spontaneous and growth hormone releasing hormone (GH-RH) induced GH secretion. METHODS: Postmenopausal women (n = 30) were enrolled and randomly subdivided in three groups (n = 10 each group): (1) treated with transdermal estradiol (50 micrograms) (Dermestrill, Rottapharm, Monza, Italy) biweekly; (2) treated with transdermal estradiol (100 micrograms) (Dermestrill, Rottapharm, Monza, Italy) biweekly; (3) treated with tibolone 2...

Recently, we developed a targeted cytotoxic analog AN-207 of luteinizing hormone-releasing hormone (LH-RH), consisting of an intensely potent derivative of doxorubicin, 2-pyrrolinodoxorubicin (AN-201) conjugated to carrier agonist [D-Lys6]LH-RH. In this study, we investigated the effects of cytotoxic analog AN-207, designed for targeted chemotherapy and radical AN-201 on pituitary function in rats. A selective damage to the pituitary gonadotroph cells was found at 1 week after a single i.v. injection of 150 nmol/kg AN-207, as evidenced by a 63% decrease in the LH-RH-stimulated release of LH in vitro...

The effect of an i.v. infusion of somatostatin (SRIH) (4.1 micrograms/min/180 min) on angiotensin II (ANG II infusion for 60 min of successively increasing doses of 4, 8 and 16 ng/kg/min; each dose for 20 min)-stimulated growth hormone (GH) and corticotropin (ACTH) release was studied in 7 normal men. In addition, 7 additional normal subjects were tested with ANG II alone (as described above), GH-RH (0.1 microgram/kg body weight as an i.v. bolus) alone or the combination of GH-RH and ANG II. The ACTH response to ANG II was not modified by SRIH infusion; in contrast, the GH response to ANG II was significantly reduced by the concomitant treatment with SRIH...

Analogues of human growth hormone-releasing hormone-(1-30)-amide [GH-RH(1-30)-amide] were tested for their ability to stimulate GH release in vivo by injecting the peptides intravenously (iv), subcutaneously (sc), and intramuscularly (im). The analogues involved derivatization with Nle27 and Gaba substituents at the C-terminus with or without D-amino acid(s) in the peptide chain. The potency of the analogues was compared to that of GH-RH(1-29)-amid testing their ability to release GH at 5, 15 and 30 min after the administration...

Forty patients with typical obstetric history of Sheehan's syndrome were reviewed retrospectively. Together with baseline laboratory values, insulin hypoglycemia test was evaluated in 15 patients, thyrotropin-releasing hormone (TRH) in 27 and luteinizing hormone-releasing hormone (LH-RH) in 7 patients. Baseline hormone values suggested secondary hypothyroidism, hypogonadotropic hypogonadism and hypocortisolemia. According to the results of the anterior pituitary stimulation tests, one patient (6.6%) showed normal cortisol response and one patient (6...