The effects of 10 years of recombinant human growth hormone (GH) in adult GH-deficient patients

Special features on insulin resistance, metabolic syndrome and vascular complications in hypopituitary patients

Pituitary hormone deficiency, hypopituitarism, is a dysfunction resulting from numerous etiologies, which can be complete or partial, and is therefore heterogeneous. This heterogeneity makes it difficult to interpret the results of scientific studies with these patients.Adequate treatment of etiologies and up-to-date hormone replacement have improved morbidity and mortality rates in patients with hypopituitarism. As GH replacement is not performed in a reasonable proportion of patients, especially in some countries, it is essential to understand the known consequences of GH replacement in each subgroup of patients with this heterogeneous dysfunction.In this review on hypopituitarism, we will address some particularities regarding insulin resistance, which is no longer common in these patients with hormone replacement therapy based on current guidelines, metabolic syndrome and its relationship with changes in BMI and body composition, and to vascular complications that need to be prevented taking into account the individual characteristics of each case to reduce mortality rates in these patients.

[Unfavourable cardiovascular consequences of adult growth hormone deficiency]

The growth hormone-insulin-like growth factor-1 (GH-IGF-1) axis plays a crucial role in maintaining the normal function of the cardiovascular system. Results of the last decades demonstrated that GH-IGF-1 takes part in regulating peripheral resistance and contributes to preserving physiological cardiac mass and left ventricular function. Vasculoprotective functions of the GH-IGF-1 axis are believed to counteract atherosclerosis. Unlike in childhood, when GH-deficiency results in growth retardation, GH deficiency does not cause specific symptoms in adults. Adult growth hormone deficiency (AGHD) is characterized by a clustering of cardiometabolic risk factors resulting in a clinical picture similar to the metabolic syndrome. Besides visceral obesity, dyslipidemia and insulin resistance, novel cardiovascular risk factors, such as chronic low-grade inflammation, oxidative stress and prothrombotic state have also been reported in AGHD and may contribute to the increased cardiometabolic risk. Based on a growing body of evidence, long-term GH-replacement improves lipid profile significantly and has a favorable impact on body composition, endothelial function, left ventricular mass as well as the novel, non-traditional cardiometabolic risk factors. Increased mortality associated with the disease is now considered to be multicausal and as such cannot be solely attributed to the GH-deficiency. The etiology of GH-deficiency, treatment of the underlying pathology as well as the inadequate treatment of coexisting hormonal deficiencies might also be responsible for the increased mortality. Nevertheless, in hypopituitarism, adequate replacement therapy including GH-substitution may result in a mortality that is comparable to the general population. Orv Hetil. 2023; 164(41): 1616-1627.

Anabolic Resistance in the Pathogenesis of Sarcopenia in the Elderly: Role of Nutrition and Exercise in Young and Old People

The development of sarcopenia in the elderly is associated with many potential factors and/or processes that impair the renovation and maintenance of skeletal muscle mass and strength as ageing progresses. Among them, a defect by skeletal muscle to respond to anabolic stimuli is to be considered. Common anabolic stimuli/signals in skeletal muscle are hormones (insulin, growth hormones, IGF-1, androgens, and β-agonists such epinephrine), substrates (amino acids such as protein precursors on top, but also glucose and fat, as source of energy), metabolites (such as β-agonists and HMB), various biochemical/intracellular mediators), physical exercise, neurogenic and immune-modulating factors, etc. Each of them may exhibit a reduced effect upon skeletal muscle in ageing. In this article, we overview the role of anabolic signals on muscle metabolism, as well as currently available evidence of resistance, at the skeletal muscle level, to anabolic factors, from both in vitro and in vivo studies. Some indications on how to augment the effects of anabolic signals on skeletal muscle are provided.

Metabolic and quality of life effects of growth hormone replacement in patients with TBI and AGHD: A pilot study

OBJECTIVE

Traumatic brain injury (TBI), a common cause of adult growth hormone deficiency (AGHD), affects 20% of Veterans returning from Iraq and Afghanistan (OEF/OIF/OND). Growth hormone replacement therapy (GHRT) improves quality of life (QoL) in AGHD but remains unexplored in this population. This pilot, observational study investigates the feasibility and efficacy of GHRT in AGHD following TBI.

DESIGN

In this 6-month study of combat Veterans with AGHD and TBI starting GHRT (N = 7), feasibility (completion rate and rhGH adherence) and efficacy (improvements in self-reported QoL) of GHRT were measured (primary outcomes). Secondary outcomes included body composition, physical and cognitive function, psychological and somatic symptoms, physical activity, IGF-1 levels and safety parameters. It was hypothesized that participants would adhere to GHRT and that QoL would significantly improve after six months.

RESULTS

Five subjects (71%) completed all study visits. All patients administered daily rhGH injections, 6 (86%) of whom consistently administered the clinically-prescribed dose. While QoL demonstrated numeric improvement, this change did not reach statistical significance (p = 0.17). Significant improvements were observed in total lean mass (p = 0.02), latissimus dorsi strength (p = 0.05), verbal learning (Trial 1, p = 0.02; Trial 5, p = 0.03), attention (p = 0.02), short-term memory (p = 0.04), and post-traumatic stress disorder (PTSD) symptoms (p = 0.03). Body weight (p = 0.02) and total fat mass (p = 0.03) increased significantly.

CONCLUSION

GHRT is a feasible and well-tolerated intervention for U.S. Veterans with TBI-related AGHD. It improved key areas impacted by AGHD and symptoms of PTSD. Larger, placebo-controlled studies testing the efficacy and safety of this intervention in this population are warranted.

Mechanisms of ageing: growth hormone, dietary restriction, and metformin

Tackling the mechanisms underlying ageing is desirable to help to extend the duration and improve the quality of life. Life extension has been achieved in animal models by suppressing the growth hormone-insulin-like growth factor 1 (IGF-1) axis and also via dietary restriction. Metformin has become the focus of increased interest as a possible anti-ageing drug. There is some overlap in the postulated mechanisms of how these three approaches could produce anti-ageing effects, with convergence on common downstream pathways. In this Review, we draw on evidence from both animal models and human studies to assess the effects of suppression of the growth hormone-IGF-1 axis, dietary restriction, and metformin on ageing.

Growth Hormone Secretory Capacity Is Associated with Cardiac Morphology and Function in Overweight and Obese Patients: A Controlled, Cross-Sectional Study

Obesity is associated with increased cardiovascular morbidity. Adult patients with growth hormone deficiency (GHD) show morpho-functional cardiological alterations. A total of 353 overweight/obese patients are enrolled in the period between 2009 and 2019 to assess the relationships between GH secretory capacity and the metabolic phenotype, cardiovascular risk factors, body composition and cardiac echocardiographic parameters. All patients underwent GHRH + arginine test to evaluate GH secretory capacity, DEXA for body composition assessment and transthoracic echocardiography. Blood samples are also collected for the evaluation of metabolic parameters. In total, 144 patients had GH deficiency and 209 patients had normal GH secretion. In comparing the two groups, we found significant differences in body fat distribution with predominantly visceral adipose tissue accumulation in GHD patients. Metabolic syndrome is more prevalent in the GHD group. In particular, fasting glycemia, triglycerides and systolic and diastolic blood pressure are found to be linearly correlated with GH secretory capacity. Epicardial fat thickness, E/A ratio and indexed ventricular mass are worse in the GHD group. In the population studied, metabolic phenotype, body composition, cardiovascular risk factors and cardiac morphology are found to be related to the GH secretory capacity. GH secretion in the obese patient seems to be an important determinant of metabolic health.

Effects of GH on the Aging Process in Several Organs: Mechanisms of Action

In order to investigate the possible beneficial effects of GH administration on the aging process, 24-month-old rats of both sexes and 10-month-old SAMP8 mice were used. Male rats showed increased fat content and decreased lean body mass together with enhanced vasoconstriction and reduced vasodilation of their aortic rings compared to young adult animals. Chronic GH treatment for 10 weeks increased lean body mass and reduced fat weight together with inducing an enhancement of the vasodilatory response by increasing eNOS and a reduction of the constrictory responses. Old SAMP8 male mice also showed insulin resistance together with a decrease in insulin production by the endocrine pancreas and a reduced expression of differentiation parameters. GH treatment decreased plasma levels and increased pancreatic production of insulin and restored differentiation parameters in these animals. Ovariectomy plus low calcium diet in rabbits induced osteoporosis Titanium implants inserted into these rabbit tibiae showed after one month lesser bone to implant (BIC) surface and bone mineral density (BMD). Local application of GH in the surgical opening was able to increase BIC in the osteoporotic group. The hippocampus of old rats showed a reduction in the number of neurons and also in neurogenesis compared to young ones, together with an increase of caspases and a reduction of Bcl-2. GH treatment was able to enhance significantly only the total number of neurons. In conclusion, GH treatment was able to show beneficial effects in old animals on all the different organs and metabolic functions studied.

Effects of adult growth hormone deficiency and replacement therapy on the cardiometabolic risk profile

Adult growth hormone deficiency (AGHD) is considered a rare endocrine disorder involving patients with childhood-onset and adult-onset growth hormone deficiency (AoGHD) and characterized by adverse cardiometabolic risk profile. Besides traditional cardiovascular risk factors, endothelial dysfunction, low-grade inflammation, impaired adipokine profile, oxidative stress and hypovitaminosis D may also contribute to the development of premature atherosclerosis and higher cardiovascular risk in patients with AGHD. Growth hormone replacement has been proved to exert beneficial effects on several cardiovascular risk factors, but it is also apparent that hormone substitution in itself does not eliminate all cardiometabolic abnormalities associated with the disease. Novel biomarkers and diagnostic techniques discussed in this review may help to evaluate individual cardiovascular risk and identify patients with adverse cardiometabolic risk profile. In the absence of disease-specific guidelines detailing how to assess the cardiovascular status of these patients, we generally recommend close follow-up of the cardiovascular status as well as low threshold for a more detailed evaluation.

Impact of Long-Term Growth Hormone Replacement Therapy on Metabolic and Cardiovascular Parameters in Adult Growth Hormone Deficiency: Comparison Between Adult and Elderly Patients

Growth hormone deficiency (GHD) in adults is due to a reduced growth hormone (GH) secretion by the anterior pituitary gland which leads to a well-known syndrome characterized by decreased cognitive function and quality of life (QoL), decreased bone mineral density (BMD), increased central adiposity with a reduction in lean body mass, decreased exercise tolerance, hyperlipidemia and increased predisposition to atherogenesis. Considering some similar features between aging and GHD, it was thought that the relative GH insufficiency of the elderly person could make an important contribution to the fragility of elderly. GH stimulation tests are able to differentiate GHD in elderly patients (EGHD) from the physiological reduction of GH secretion that occurs with aging. Although there is no evidence that rhGH replacement therapy increases the risk of developing Diabetes Mellitus (DM), reducing insulin sensitivity and inducing cardiac hypertrophy, long-term monitoring is, however, also mandatory in terms of glucose metabolism and cardiovascular measurements. In our experience comparing the impact of seven years of rhGH treatment on metabolic and cardiovascular parameters in GHD patients divided in two groups [adult (AGHD) and elderly (EGHD) GHD patients], effects on body composition are evident especially in AGHD, but not in EGHD patients. The improvements in lipid profile were sustained in all groups of patients, and they had a lower prevalence of dyslipidemia than the general population. The effects on glucose metabolism were conflicting, but approximately unchanged. The risk of DM type 2 is, however, probably increased in obese GHD adults with impaired glucose homeostasis at baseline, but the prevalence of DM in GHD is like that of the general population. The increases in glucose levels, BMI, and SBP in GHD negatively affected the prevalence of Metabolic Syndrome (MS) in the long term, especially in AGHD patients. Our results are in accordance to other long-term studies in which the effects on body composition and lipid profile are prominent.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY GUIDELINES FOR MANAGEMENT OF GROWTH HORMONE DEFICIENCY IN ADULTS AND PATIENTS TRANSITIONING FROM PEDIATRIC TO ADULT CARE

Objective: The development of these guidelines is sponsored by the American Association of Clinical Endocrinologists (AACE) Board of Directors and American College of Endocrinology (ACE) Board of Trustees and adheres with published AACE protocols for the standardized production of clinical practice guidelines (CPG). Methods: Recommendations are based on diligent reviews of clinical evidence with transparent incorporation of subjective factors, according to established AACE/ACE guidelines for guidelines protocols. Results: The Executive Summary of this 2019 updated guideline contains 58 numbered recommendations: 12 are Grade A (21%), 19 are Grade B (33%), 21 are Grade C (36%), and 6 are Grade D (10%). These detailed, evidence-based recommendations allow for nuance-based clinical decision-making that addresses multiple aspects of real-world care of patients. The evidence base presented in the subsequent Appendix provides relevant supporting information for the Executive Summary recommendations. This update contains 357 citations of which 51 (14%) are evidence level (EL) 1 (strong), 168 (47%) are EL 2 (intermediate), 61 (17%) are EL 3 (weak), and 77 (22%) are EL 4 (no clinical evidence). Conclusion: This CPG is a practical tool that practicing endocrinologists and regulatory bodies can refer to regarding the identification, diagnosis, and treatment of adults and patients transitioning from pediatric to adult-care services with growth hormone deficiency (GHD). It provides guidelines on assessment, screening, diagnostic testing, and treatment recommendations for a range of individuals with various causes of adult GHD. The recommendations emphasize the importance of considering testing patients with a reasonable level of clinical suspicion of GHD using appropriate growth hormone (GH) cut-points for various GH-stimulation tests to accurately diagnose adult GHD, and to exercise caution interpreting serum GH and insulin-like growth factor-1 (IGF-1) levels, as various GH and IGF-1 assays are used to support treatment decisions. The intention to treat often requires sound clinical judgment and careful assessment of the benefits and risks specific to each individual patient. Unapproved uses of GH, long-term safety, and the current status of long-acting GH preparations are also discussed in this document. LAY ABSTRACT This updated guideline provides evidence-based recommendations regarding the identification, screening, assessment, diagnosis, and treatment for a range of individuals with various causes of adult growth-hormone deficiency (GHD) and patients with childhood-onset GHD transitioning to adult care. The update summarizes the most current knowledge about the accuracy of available GH-stimulation tests, safety of recombinant human GH (rhGH) replacement, unapproved uses of rhGH related to sports and aging, and new developments such as long-acting GH preparations that use a variety of technologies to prolong GH action. Recommendations offer a framework for physicians to manage patients with GHD effectively during transition to adult care and adulthood. Establishing a correct diagnosis is essential before consideration of replacement therapy with rhGH. Since the diagnosis of GHD in adults can be challenging, GH-stimulation tests are recommended based on individual patient circumstances and use of appropriate GH cut-points. Available GH-stimulation tests are discussed regarding variability, accuracy, reproducibility, safety, and contraindications, among other factors. The regimen for starting and maintaining rhGH treatment now uses individualized dose adjustments, which has improved effectiveness and reduced reported side effects, dependent on age, gender, body mass index, and various other individual characteristics. With careful dosing of rhGH replacement, many features of adult GHD are reversible and side effects of therapy can be minimized. Scientific studies have consistently shown rhGH therapy to be beneficial for adults with GHD, including improvements in body composition and quality of life, and have demonstrated the safety of short- and long-term rhGH replacement. Abbreviations: AACE = American Association of Clinical Endocrinologists; ACE = American College of Endocrinology; AHSG = alpha-2-HS-glycoprotein; AO-GHD = adult-onset growth hormone deficiency; ARG = arginine; BEL = best evidence level; BMD = bone mineral density; BMI = body mass index; CI = confidence interval; CO-GHD = childhood-onset growth hormone deficiency; CPG = clinical practice guideline; CRP = C-reactive protein; DM = diabetes mellitus; DXA = dual-energy X-ray absorptiometry; EL = evidence level; FDA = Food and Drug Administration; FD-GST = fixed-dose glucagon stimulation test; GeNeSIS = Genetics and Neuroendocrinology of Short Stature International Study; GH = growth hormone; GHD = growth hormone deficiency; GHRH = growth hormone-releasing hormone; GST = glucagon stimulation test; HDL = high-density lipoprotein; HypoCCS = Hypopituitary Control and Complications Study; IGF-1 = insulin-like growth factor-1; IGFBP = insulin-like growth factor-binding protein; IGHD = isolated growth hormone deficiency; ITT = insulin tolerance test; KIMS = Kabi International Metabolic Surveillance; LAGH = long-acting growth hormone; LDL = low-density lipoprotein; LIF = leukemia inhibitory factor; MPHD = multiple pituitary hormone deficiencies; MRI = magnetic resonance imaging; P-III-NP = procollagen type-III amino-terminal pro-peptide; PHD = pituitary hormone deficiencies; QoL = quality of life; rhGH = recombinant human growth hormone; ROC = receiver operating characteristic; RR = relative risk; SAH = subarachnoid hemorrhage; SDS = standard deviation score; SIR = standardized incidence ratio; SN = secondary neoplasms; T3 = triiodothyronine; TBI = traumatic brain injury; VDBP = vitamin D-binding protein; WADA = World Anti-Doping Agency; WB-GST = weight-based glucagon stimulation test.

[Current aspects of diagnosis and treatment of adult GH-deficiency]

Adult growth hormone (GH) deficiency (AGHD) is a condition characterized by alterations in body composition, lipid and carbohydrate metabolism, bone mineral density and poor quality of life; however, clinical presentations of AGHD are mostly non-specific. Untreated AGHD is associated with increased cardiovascular morbidity and mortality. Stimulation tests are used for the diagnosis: insulin tolerance test, glucagon stimulation test, growth-hormone releasing hormone and arginine stimulation test. Moreover, in 2017 FDA approved the use of macimorelin (oral GH secretagogue) for the diagnosis of AGHD. In childhood GH-deficiency, apolipoprotein A-IV, CFHR4 (complement factor H-related protein 4) and PBP (platelet basic protein) were identified as potential biomarkers of the disease, however, this was not investigated in AGHD. GH treatment starts from the minimal dose, which allows minimizing the adverse effects. According to published meta-analyses, AGHD treatment generally does not lead to increased risk of malignancy and recurrence of sellar neoplasms in adult patients. Published data on GH receptor polymorphism associations with treatment efficacy remains controversial. Development of long-acting GH formulations is a currect perspective for the increase of treatment compliance.

Epilepsy, depression, and growth hormone

Depression affects a large proportion of patients with epilepsy, and is likely due in part to biological mechanism. Hormonal dysregulation due to the disruptive effects of seizures and interictal epileptiform discharges on the hypothalamic-pituitary-adrenal axis likely contributes to high rates of depression in epilepsy. This paper reviews the largely unexplored role of neuroendocrine factors in epilepsy-related depression, focusing on Growth Hormone (GH). While GH deficiency is traditionally considered a childhood disorder manifested by impaired skeletal growth, GH deficiency in adulthood is now recognized as a serious disorder characterized by impairments in multiple domains including mood and quality of life. Could high rates of depression in patients with epilepsy relate to subtle GH deficiency? Because GH replacement therapy has been shown to improve mood and quality of life in patients with GH deficiency, this emerging area may hold promise for patients suffering from epilepsy-related depression.

Progression of pituitary tumours: impact of GH secretory status and long-term GH replacement therapy

BACKGROUND

Most patients treated for hypothalamic-pituitary tumours develop GH deficiency. Long-term GH replacement treatment in adults with a previous history of hypothalamic-pituitary tumour could represent a concern about increasing the risk of tumour enlargement or recurrence.

PURPOSE

To assess the progression risk of hypothalamic-pituitary tumours according to the GH secretory status (normal GH secretion, non-treated and treated GH deficiency). and determine the predictors of neoplasm recurrence.

METHODS

We retrospectively reviewed 309 patients with tumours of the hypothalamic-pituitary region (294 subjects underwent neurosurgery while 81 radiotherapy) who were followed for 9.9 ± 8.3 years.

RESULTS

Out of 309 patients, 200 were affected by severe GH deficiency; 90 of these underwent GH therapy. The tumour progression rate did not differ among GH-sufficient, not-treated and treated GH-deficient patients (16.5%, 16.4%. and 10.0%, respectively). In a multivariate analysis, previous radiotherapy (HR 0.12, CI 0.03-0.52, p < 0.005) and residual tumour (HR 8.20, CI 2.38-28.29, p < 0.001) were independent predictors of recurrence. After controlling for multiple covariates, the tumour recurrence risk in GH-sufficient and GH-treated patients was similar to that observed in not-treated GH-deficient patients.

CONCLUSIONS

With limitations of retrospective analysis, GH therapy is not associated with an increased progression rate of tumours of the hypotalamic-pituitary region during long follow-up, thus supporting the long-term safety of GH treatment. The only predictors of tumour recurrence appear to be the presence of residual disease and the lack of radiotherapy.

Effect of pre- and post-treatment with Bacopa monnieri (Brahmi) on phencyclidine-induced disruptions in object recognition memory and cerebral calbindin, parvalbumin, and calretinin immunoreactivity in rats

Background: Decreased gamma-aminobutyric acid (GABA)-ergic neurons in the brain of both schizophrenic patients and animal models indicates that impairment of GABAergic function is implicated in pathophysiology of the disorder. Decreased GABAergic neurotransmission might be also involved in cognitive impairment, which is developed in schizophrenia. Brahmi (Bacopa monnieri) could be a new treatment and prevention for this cognitive deficit in schizophrenia by increasing GABAergic neurons to a normal level. Aim: The authors aimed to study cognitive-enhancement- and neuroprotective-effects of Brahmi on novel object recognition memory and GABAergic neuronal density, defined by the presence of calcium binding proteins (CBPs; calbindin (CB), parvalbumin (PV), and calretinin (CR)) in a sub-chronic (2 mg/kg, Bid, ip) phencyclidine (PCP) rat model of schizophrenia. Materials and methods: In the cognitive-enhancement-effect study rats were assigned to three groups; Group-1: Control, Group-2: PCP-administration, and Group-3: PCP+Brahmi. In the neuroprotective-effect study rats were assigned to three groups; Group-1: Control, Group-2: PCP-administration, and Group-3: Brahmi+PCP. A discrimination ratio (DR) representing cognitive ability was obtained from the novel object recognition task. CB, PV, and CR immunodensity were measured in the prefrontal cortex, striatum, and cornuammonis fields 1-3 (CA1-3) using immunohistochemistry. Results: Reduced DR was found in the PCP group, which occurred alongside reduced CB, PV, and CR in all brain regions except for CR in the striatum and CA1-3 in the cognitive-enhancement-effect study. PCP+Brahmi showed a higher DR score with increased CB in the prefrontal cortex and striatum, increased PV in the prefrontal cortex and CA1-3, and increased CR in the prefrontal cortex. The Brahmi+PCP group showed higher DR score with increased CB in all areas, increased PV in the striatum, and increased CR in the prefrontal cortex and striatum. Conclusion: The present study demonstrated the effects, both partial restoration of cognitive deficit and neuroprotection, of Brahmi, and elucidated its underlying mechanism of actions via increasing GABAergic neurons in a PCP-induced schizophrenic-like model.

The Use and Abuse of Human Growth Hormone in Sports

CONTEXT

Recombinant human growth hormone (rHGH) has become a target of abuse in the sporting world. Conversely, sports medicine clinicians may encounter athletes using rHGH to achieve normalcy in the context of growth hormone (GH) deficiency.

EVIDENCE ACQUISITION

Medline and PubMed databases were queried using the following keywords: GH, GH physiology, GH deficiency, acromegaly, GH athlete, GH sports, GH athletic performance, and GH deficiency concussion. Articles focusing on GH physiology, deficiency, excess, and its effects in both deficient and healthy patients were included.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 3.

RESULTS

GH is a naturally occurring hormone with important roles in human physiology. Patients with GH deficiency (GHD) present variably, and GHD has numerous etiologies. rHGH treatment has substantial therapeutic benefits for patients with GHD. The benefits of rHGH treatment in otherwise-healthy adults are uncertain. GH excess may cause health problems such as acromegaly. Professional, collegiate, and international sports leagues and associations have banned rHGH use to maintain athlete health, safety, and fair play. Athletes misusing GH may face prolonged suspensions from competition. Implementing GH abuse testing is challenging, but new methods, such as the biomarker testing procedure, are being finalized.

CONCLUSION

rHGH is not only an important therapeutic agent for GH-deficient patients but also a target of abuse in competitive athletics. Its benefits in a healthy, adult population are uncertain. A safe exercise and competition plan, developed with a physician knowledgeable of GH use, physiology, and abuse potential, should be of benefit to a longitudinal clinician-patient relationship.

Treatment of adult growth hormone deficiency with human recombinant growth hormone: an update on current evidence and critical review of advantages and pitfalls

Adult-onset growth-hormone (GH) deficiency (GHD) is a rare disorder, which most commonly results from pituitary or peripituitary tumors and their treatment, and is characterized by alterations in body composition, carbohydrate and lipid metabolism, bone mineral density, cardiovascular risk profile and quality of life, all of which may contribute to an increased morbidity and mortality. Since recombinant human GH (rhGH) became available in 1985, several studies have provided evidence of its beneficial effects, despite the potential risk of developing adverse effects, and much clinical experience has been accumulated. However, in adults, the precise therapeutic role of GH replacement therapy and the individual response to it remains highly variable and is still a matter of debate. In this article, we present a critical review of the available evidence on rhGH replacement therapy in GHD adults, emphasizing the pitfalls clinicians encounter in the diagnosis of GHD and monitoring of rhGH replacement therapy. We will cover all the relevant aspects regarding the potential usefulness of GH treatment, including the hot topic of mortality.

Treatment with Growth Hormone for Adults with Growth Hormone Deficiency Syndrome: Benefits and Risks

Pharmacological treatment of growth hormone deficiency (GHD) in adults began in clinical practice more than 20 years ago. Since then, a great volume of experience has been accumulated on its effects on the symptoms and biochemical alterations that characterize this hormonal deficiency. The effects on body composition, muscle mass and strength, exercise capacity, glucose and lipid profile, bone metabolism, and quality of life have been fully demonstrated. The advance of knowledge has also taken place in the biological and molecular aspects of the action of this hormone in patients who have completed longitudinal growth. In recent years, several epidemiological studies have reported interesting information about the long-term effects of GH replacement therapy in regard to the possible induction of neoplasms and the potential development of diabetes. In addition, GH hormone receptor polymorphism could potentially influence GH therapy. Long-acting GH are under development to create a more convenient GH dosing profile, while retaining the excellent safety, efficacy, and tolerability of daily GH. In this article we compile the most recent data of GH replacement therapy in adults, as well as the molecular aspects that may condition a different sensitivity to this treatment.

Changes in Thyroid Hormone Are Not Involved in Regulating Brain Protein Synthesis in Adults Rats Fed Ornithine

Brain protein synthesis and the plasma concentration of growth hormone (GH) are sensitive to dietary ornithine. However, dietary ornithine does not increase brain protein synthesis in hypophysectomized rats. Because hypophysectomy may decrease the secretion of thyroid stimulated hormone (TSH), we assessed whether the regulation of brain protein synthesis was mediated by changes in the plasma concentrations of thyroid hormone and ghrelin in the 6-propyl-2-thiouracil (PTU, thyroid inhibitor)-treated or control adult rats fed ornithine. The four experimental groups consisted of PTU-treated and control (24-wk-old) male rats given 0% or 0.7% ornithine-HCl added to a 20% casein diet. The plasma concentrations of GH and ghrelin, and the fractional rates of protein synthesis and RNA activity [g protein synthesized/(g RNA•d)] in the brains were significantly increased after treatment with the 20% casein + 0.7% ornithine compared with the 20% casein diet alone in both the PTU-treated and control groups. Ornithine supplementation to the basal diet did not affect the plasma concentration of T₃. The RNA concentration (mg RNA/g protein) was not related to the fractional rate of protein synthesis in the brain regions. The results suggest that dietary ornithine likely increases the rate of brain protein synthesis in control and PTU-treated rats, and that the ornithine-induced increase in the GH concentration may stimulate mainly brain protein synthesis via ghrelin. RNA activity is at least partly related to the fractional rate of brain protein synthesis.

Effects of Growth Hormone Replacement on Peripheral Muscle and Exercise Capacity in Severe Growth Hormone Deficiency

OBJECTIVE

The aim of this study is to evaluate the effect of growth hormone therapy (rGH) on mitochondrial function on peripheral muscle and to correlate with exercise capacity in subjects with severe adult growth hormone deficiency (GHD).

DESIGN

Six months, double-blind, randomized, crossover, placebo-controlled trial of subcutaneous rGH in 17 patients with GHD.

MEASUREMENTS

Quadriceps muscle biopsies were obtained at baseline, 3 months, and 6 months to measure succinate dehydrogenase (SDH) to assess mitochondrial activity. Exercise capacity was measured with cardiopulmonary exercise testing. Lipids, glycemic parameters, and body fat levels were also measured.

RESULTS

Serum insulin-like growth factor 1 (IGF1) levels reduced fat mass by 3.2% (p < 0.05) and normalized with rGH in the active phase (p < 0.005). Patients showed an increase in SDH (p < 0.01) from base line that differed between placebo and rGH therapy treatment groups (p < 0.05): those treated by rGH followed by placebo showed a significant increase in SDH (p < 0.001) followed by a decrease, with a significant between group difference at the end of 6 months (p < 0.05). No significant improvements or correlation with exercise capacity was found.

CONCLUSION

Short-term rGH for 3 months normalized IGF1 levels, reduced fat mass, and had a significant effect on mitochondrial function, but exercise capacity was unchanged.

CLINICAL TRIAL REGISTRATION

Number ISRCTN94165486.

Effects of growth hormone on glucose metabolism and insulin resistance in human

Growth hormone (GH) is important for promotion of somatic growth and the regulation of substrate metabolism. Metabolic action of GH occurs in multiple tissues including the liver, muscle, fat and pancreas either directly or indirectly through insulin-like growth factor 1. The diabetogenic action of GH has been well-described in previous in vivo studies. In this paper, we review the metabolic effects of GH on peripheral tissues focusing on glucose metabolism and insulin resistance, and discuss results from human studies on the long-term effects of GH administration on insulin resistance and hyperglycemia.

One-year GH replacement therapy reduces early cardiac target organ damage (TOD) in adult GHD patients

Hypopituitarism reduces life expectancy and increases the risk of cardiovascular and cerebrovascular diseases, as well as death. Abnormalities in the cardiovascular system may be independently related to GH deficiency (GHD). The aim of this study was to prospectively investigate coronary flow reserve and diastolic function in GHD adult patients at diagnosis and after 1 year of GH replacement therapy. As control group, an age- and sex-matched population was chosen. All patients and controls were non-smokers, non-diabetic, and normotensive, with no history of vascular disease. 14 patients with adult-onset GHD and 17 controls represent the two study groups. Anthropometric data, blood pressure, lipid profile, glycosylated hemoglobin (HbA1c) and IGF-I plasma levels, coronary flow reserve (CFR), and LV diastolic function (evaluated by E/A) were collected in all subjects before and after 12 months of GH replacement therapy. Compared with controls, systolic and diastolic blood pressure and LDL cholesterol levels were significantly higher at baseline and return, comparable to controls after 1 year of GH replacement (GHRT). GHD patients showed a blunted CFR at baseline (P < 0.001) and a significant improvement after GHRT, returning to values comparable with those recorded in the control group. In addition, after therapy a significant (P < 0.001) improvement in E/A was recorded. One year of GH therapy improves CFR and E/A in the patient population analyzed, thereby encouraging the early start of GHRT.

Resolution of non-alcoholic steatohepatitis after growth hormone replacement in a pediatric liver transplant patient with panhypopituitarism

NAFLD is a common condition linked to obesity, type 2 diabetes, and metabolic syndrome. Simple hepatic steatosis is a risk factor for inflammatory reactions in the liver (NASH), which may lead to cirrhosis. While the mechanism is unclear, NAFLD and NASH are associated with panhypopituitarism, which in the pediatric population often results from craniopharyngioma or pituitary adenoma and the sequelae of treatment, causing hypothyroidism, adrenal insufficiency, hypogonadotropic hypogonadism, and GH deficiency. Refractory NAFLD in panhypopituitarism may be amenable to GH replacement. Here, we report a pediatric case of NASH secondary to panhypopituitarism from craniopharyngioma, which recurred by 11 months after LDLT. Despite low-dose GH replacement, the patient remained GH deficient. Pubertal dosed GH therapy led to rapid and complete resolution of hepatic steatosis, which we tracked using serial ¹ H MRS. Pediatric patients with NASH cirrhosis secondary to panhypopituitarism can be good candidates for liver transplantation, but hormone deficiencies predispose to recurrence after transplant. High-dose GH replacement should be considered in pediatric patients with GH deficiency and recurrent disease. A multidisciplinary team approach is essential for successful outcomes.

Seven years of follow up of trabecular bone score, bone mineral density, body composition and quality of life in adults with growth hormone deficiency treated with rhGH replacement in a single center

BACKGROUND

Adult growth hormone deficiency (AGHD) is characterized by impaired physical activity, diminished quality of life (QoL), weight and fat mass gain, decreased muscle mass and decreased bone mineral density (BMD). The aim of this study was to evaluate the effects of long-term treatment (7 years) with recombinant human growth hormone (rhGH) on metabolic parameters, body composition (BC), BMD, bone microarchitecture and QoL.

PATIENTS AND METHODS

In this prospective study, BMD and BC were assessed by dual-energy X-ray absorptiometry (DXA). Bone microarchitecture was assessed with the trabecular bone score (TBS). The QoL-AGHDA test was used to assess QoL.

RESULTS

A total of 18 AGHD patients (mean age, 37.39 ± 12.42) were included. Body weight and body mass index (BMI) showed a significant increase after 7 years (p = 0.03 and p = 0.001, respectively). There was a significant tendency of body fat mass (BFM) (p = 0.028) and lean body mass (LBM) (p = 0.005) to increase during the 7 years of rhGH treatment. There was a significant increase in lumbar spine (LS) BMD (p = 0.01). TBS showed a nonsignificant decrease after 7 years of treatment, with a change of -0.86% ± 1.95. QoL showed a large and significant improvement (p = 0.02).

CONCLUSION

Long-term rhGH treatment in AGHD patients induces a large and sustained improvement in QoL. Metabolic effects are variable with an increase in LBM as well as in BMI and BFM. There is a positive effect on BMD based on the increase in LS BMD, which stabilizes during long-term therapy and is not associated with a similar increase in bone microarchitecture.

Effects of gender, body weight, and blood glucose dynamics on the growth hormone response to the glucagon stimulation test in patients with pituitary disease

OBJECTIVE

Body weight blunts the growth hormone (GH) response to provocative stimuli. The appropriate GH cut-off to confirm GH deficiency in obese and overweight patients undergoing the glucagon stimulation test (GST) has recently been questioned. We hypothesized that the peak GH would be inversely related to the nadir blood glucose (BG) after glucagon and that this may be a mechanism influencing peak GH in overweight patients. This retrospective study examined effects of gender, body weight, and BG dynamics on GH response to GST in patients evaluated in our Pituitary Center.

DESIGN

Adult patients who underwent GST from September 2009-2014 were included. Continuous variable comparisons were analyzed using the Mann-Whitney U-test and categorical data by Fisher's Exact Test. Spearman correlation was used to determine associations between continuous variables.

RESULTS

42 patients (N=28, 66.7% female) had sufficient data for analysis. Obese patients (N=26) had a reduced GH response, summarized as GH area under the curve (AUC) (p=0.03 vs. non-obese patients) and higher BG during GST, summarized as AUC (p<0.01 vs. non-obese patients). Obese women (N=19), in particular, stimulated lower (p=0.03 vs. non-obese women) and had a higher nadir BG (p=0.03 vs. non-obese women). While weight correlated with extent (rs=0.35; p=0.02) and timing (rs=0.31; p=0.05) of nadir BG reached, there was no significant correlation between BG dynamics and the GH response in the total population (N=42). Ten patients (7 with pan anterior hypopituitarism, defined as 3 anterior pituitary deficiencies) had a peak GH≤0.1ng/mL during GST. When these subjects with a negligible peak GH response were excluded from the analysis, weight was associated with GH AUC (rs=-0.45; p=0.01), peak GH response (rs=-0.42; p=0.02) and nadir BG (rs=0.48; p<0.01). Furthermore, the nadir BG achieved during GST was inversely related to GH AUC (rs=-0.38; p=0.03) and peak GH (rs=-0.37; p=0.04) such that patients (N=32) with higher nadir BG had lower peak GH in response to glucagon.

CONCLUSIONS

Obese patients, particularly women, do not respond as robustly to glucagon stimulation. These data suggest that there exists an altered BG profile during GST in obese individuals, and that a less robust hypoglycemic stimulus may contribute to an impaired GH response. We suggest measuring BG levels during glucagon stimulation testing to assist with clinical interpretation of GH dynamics. The diagnostic accuracy of the GST in patients with known disorders in glucose metabolism and those taking anti-diabetic medications deserves further study.

Effect of growth hormone in experimental tooth movement

The aim of this study was to evaluate, by histological analysis, the effect of growth hormone (GH) on periodontal ligament and alveolar bone during experimental tooth movement in rats. Eighty male Wistar rats divided into control (C) and experimental (E) groups were examined after 3, 7, 14 and 21 days under controlled climate conditions. Orthodontic force (30 cN) was applied on the maxillary first molar by an orthodontic appliance. Group E received 0.1 IU/kg/day of GH and Group C received 0.5 mL/kg/day of saline. The samples were processed and evaluated under optical microscopy and polarized light microscopy. The Kruskal Wallis test was applied to compare the intergroup variables at 5% significance level. Group E presented a larger number of osteoclasts on the 3rd and 7th days and Howship lacunae on the 3 rd day, a smaller number of blood vessels and greater amount of mature collagen on the 3 rd and 7 th days than Group C (p<0.05). It was concluded that GH accelerated and intensified bone resorption and produced delay in immature collagen formation during experimental tooth movement.

Reviewing the safety of GH replacement therapy in adults

CONTEXT

Systematic data on safety of growth hormone (GH) replacement therapy in adult GH deficiency is lacking.

OBJECTIVE

To systematically describe safety of adult GH replacement therapy on glucose metabolism and long term safety.

DESIGN

A systematic web-based search of PubMed was performed guided by the Standard Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

OUTCOME

Randomised controlled trials of ≥3 months and open trials for ≥12 months with more than 50 adult patients (50 patient years, prospective and retrospective) including adverse event reporting as well as articles on mortality primarily on adult onset patients, reporting mortality ratios on GH treated patients, were included for the review.

RESULTS

Based on the defined selection criteria 94 studies were included. The short-term early placebo controlled trials did not demonstrate an increased frequency of diabetes mellitus (DM) and the long-term open studies did not consistently show an increased incidence of DM during GH replacement. The concern that long-term GH replacement might increase the risk of primary cancer, secondary neoplasia after tumour treatment and recurrence of previous tumours was not evident in the study data.

CONCLUSION

Based on available data, short- and long-term adult GH replacement in patients with severe GH deficiency and hypopituitarism is safe. However, the small number of subjects, limitation of long-term of GH treatment data and absence of an adequate control population is still a limitation for the interpretation of these data.

Low myocardial glucose uptake in Turner syndrome is unaffected by growth hormone: a randomized, placebo-controlled FDG-PET study

BACKGROUND

An unfavourable cardiovascular and metabolic phenotype causes threefold excess mortality in Turner syndrome (TS), and perturbed cardiac substrate metabolism is increasingly recognized as a common component of cardiovascular and metabolic diseases. We therefore hypothesized that myocardial glucose uptake (MGU) is reduced in TS and that growth hormone (GH) treatment improves MGU. To this end, this controlled trial elucidates MGU in TS and the impact of 6 months of growth hormone treatment on MGU.

METHODS AND RESULTS

Women with TS (n = 9) were examined at baseline, sequentially treated with either Norditropin(®) SimpleXx or placebo and re-examined after 6 months. MGU and myocardial blood flow (MBF) were measured using 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography (FDG-PET) during a hyperinsulinaemic euglycaemic clamp (at baseline and 6 months). Blood pressure measurement, blood sampling, echocardiography and dual energy X-ray absorptiometry scan were also performed. Age-matched female controls (n = 9) were examined once. Baseline MGU was reduced in TS (0.24 ± 0.08 vs. 0.36 ± 0.13 μmol/g/min in controls; P = 0.036) despite similar insulin sensitivity (whole body glucose uptake (M-value): 9.69 ± 1.86 vs. 9.86 ± 2.58 mg/(min*kg) in controls; P = 0.9). Six months of GH carried no impact on MGU (0.25 ± 0.08 vs. 0.26 ± 0.12 μmol/g/min in the placebo group; P = 0.8). Plasma glucose, low-density cholesterol and triglycerides increased, while M-value and exercise capacity decreased during 6 months of GH treatment.

CONCLUSION

MGU is reduced in TS despite normal insulin sensitivity. GH treatment does not alter MGU despite decreased whole body insulin sensitivity. A perturbed cardiac glucose uptake appears to be a feature of TS.

Possible predictors for QOL improvement following GH replacement therapy in adult GHD

In addition to impaired physical activity, adult GH deficiency (GHD) can decrease quality of life (QOL). Hence, assessment of QOL is important to evaluate the efficacy of GH replacement therapy. This study aimed to identify factors that may be predictive of long-term improvement in QOL among clinical/laboratory variables during GH replacement therapy. The analysis included 83 Japanese adults with GHD who participated in the Hypopituitary Control and Complications Study (HypoCCS). Correlations between the change from baseline in clinical/laboratory variables at 6 months and the change from baseline in Quality of life (Short-Form 36 [SF-36] component scores) at 12 months were examined. Unexpectedly, all component scores were negatively correlated with the change in fasting plasma glucose concentration (FPG) (physical component summary [PCS], r = -0.456; mental component summary [MCS], r = -0.523; role/social component summary [RCS], r = -0.433). The change in MCS was positively correlated with the change in insulin-like growth factor-1 standard deviation score (IGF-1 SDS) (r = 0.417). The change in PCS was positively correlated with the change in body fat (r = 0.551). The change in RCS was positively correlated with the change in waist circumference (r = 0.528). Short-term changes in several clinical/laboratory variables, most notably FPG and IGF-1 SDS, were correlated with long-term changes in QOL. The clinical importance of these correlations for predicting GH replacement treatment efficacy warrants further investigation.

Effect of dietary γ-aminobutyric acid on the nerve growth factor and the choline acetyltransferase in the cerebral cortex and hippocampus of ovariectomized female rats

The brain protein synthesis and the plasma concentration of growth hormone (GH) is sensitive to the dietary γ-aminobutyric acid (GABA) in ovariectomized female rats; however, the role of dietary GABA on biomarkers including nerve growth factor (NGF) and choline acetyltransferase for the function of cholinergic neurons remains unknown in ovariectomized female rats. The purpose of this study was to determine whether the dietary GABA affects the concentration and mRNA level of NGF, and the activity of choline acetyltransferase in the brains of ovariectomized female rats. Experiments were done on two groups of 24-wk-old ovariectomized female rats given 0 or 0.5% GABA added to a 20% casein diet. The concentrations of NGF and activities of choline acetyltransferase in the cerebral cortex and hippocampus, and mRNA level of NGF in the hippocampus increased significantly with the 20% casein+0.5% GABA compared with the 20% casein diet alone. In the hippocampus, the mRNA level of NGF significantly correlated with the NGF concentration (r=0.714, p<0.01). These results suggest that the administration of GABA to ovariectomized female rats is likely to control the mRNA level and concentration of NGF and cause an increase in the activity of choline acetyltransferase in the brains.

Unusual effects of GH deficiency in adults: a review about the effects of GH on skin, sleep, and coagulation

Based on the literature data in the last two decades, growth hormone deficiency (GHD) in adults has been accepted as a clinical entity. Due to the presence of GH and IGF-I receptors throughout the body, the physiological effects of the GH-IGF-I axis are still under investigation. The effects of GH on skin, sleep, and coagulation parameters in adults have only been investigated in detail only in the recent years. In this review, our aim was to summarize the literature regarding the effects of GHD and GH replacement treatment on the skin, sleep, and coagulation parameters in adults.

[Benefits and risks of growth hormone in adults with growth hormone deficiency]

Adult growth hormone (GH) deficiency is a well-recognized clinical syndrome with adverse health consequences. Many of these may improve after replacement therapy with recombinant GH. This treatment induces an increase in lean body mass and a decrease in fat mass. In long-term studies, bone mineral density increases and muscle strength improves. Health-related quality of life tends to increase after treatment with GH. Lipid profile and markers of cardiovascular risk also improve with therapy. Nevertheless, GH replacement therapy is not without risk. According to some studies, GH increases blood glucose, body mass index and waist circumference and may promote long-term development of diabetes and metabolic syndrome. Risk of neoplasia does not appear to be increased in adults treated with GH, but there are some high-risk subgroups. Methodological shortcomings and difficulties inherent to long-term studies prevent definitive conclusions about the relationship between GH and survival. Therefore, research in this field should remain active.

Growth hormone plus resistance exercise attenuate structural changes in rat myotendinous junctions resulting from chronic unloading

Myotendinous junctions (MTJs) are specialized sites on the muscle surface where forces generated by myofibrils are transmitted across the sarcolemma to the extracellular matrix. At the ultrastructural level, the interface between the sarcolemma and extracellular matrix is highly folded and interdigitated at these junctions. In this study, the effect of exercise and growth hormone (GH) treatments on the changes in MTJ structure that occur during muscle unloading, has been analyzed. Twenty hypophysectomized rats were assigned randomly to one of five groups: ambulatory control, hindlimb unloaded, hindlimb unloaded plus exercise (3 daily bouts of 10 climbs up a ladder with 50% body wt attached to the tail), hindlimb unloaded plus GH (2 daily injections of 1 mg/kg body wt, i.p.), and hindlimb unloaded plus exercise plus GH. MTJs of the plantaris muscle were analyzed by electron microscopy and the contact between muscle and tendon was evaluated using an IL/B ratio, where B is the base and IL is the interface length of MTJ's digit-like processes. After 10 days of unloading, the mean IL/B ratio was significantly lower in unloaded (3.92), unloaded plus exercise (4.18), and unloaded plus GH (5.25) groups than in the ambulatory control (6.39) group. On the opposite, the mean IL/B ratio in the group treated with both exercise and GH (7.3) was similar to control. These findings indicate that the interaction between exercise and GH treatments attenuates the changes in MTJ structure that result from chronic unloading and thus can be used as a countermeasure to these adaptations.

Updates in growth hormone treatment and mortality

PURPOSE OF REVIEW

To review the literature with regard to mortality in patients with hypopituitarism with a focus on the role of growth hormone (GH) deficiency and therapy.

RECENT FINDINGS

Mortality is increased in hypopituitarism, particularly in female patients. In recent years mortality rates appear to be trending downwards towards that of the general population. Recent studies from retrospective or postmarketing surveillance studies have suggested that patients who receive GH therapy may not have increased mortality. Recent studies regarding mortality in paediatric patients treated with GH are conflicting and this area needs further study.

SUMMARY

There are several important limitations of available data regarding mortality in hypopituitarism and even more so in the impact of GH therapy, which need to be taken into account when interpreting the available data. The data regarding mortality in patients treated with GH as children is an area of much debate and will need further studies to clarify, given the conflicting reports in recent studies.

Diagnosis and treatment of growth hormone deficiency in adults

The availability of synthetic recombinant human growth hormone (GH) in potentially unlimited quantities since the 1980s has improved understanding of the many nonstatural effects of GH on metabolism, body composition, physical and psychological function, as well as the consequences of GH deficiency in adult life. Adult GH deficiency is now recognized as a distinct if nonspecific syndrome with considerable adverse health consequences. GH replacement therapy in lower doses than those used in children can reverse many of these abnormalities and restore functional capacities toward or even to normal; if dosed appropriately, GH therapy has few adverse effects. Although some doubts remain about possible long-term risks of childhood GH therapy, most registries of adult GH replacement therapy, albeit limited in study size and duration, have not shown an increased incidence of cancers or of cardiovascular morbidity or mortality.

Young little mice express a premature cardiovascular aging phenotype

To investigate the effect of growth hormone and insulin-like growth factor 1 deficiency on the aging mouse arterial system, we compared the hemodynamics in young (4 months) and old (30 months) growth hormone-releasing hormone receptor null dwarf (Little) mice and their wild-type littermates. Young Little mice had significantly lower peak and mean aortic velocity and significantly higher aortic impedance than young wild-type mice. However, unlike the wild-type mice, there were no significant changes in arterial function with age in the Little mice. Aortic pulse wave velocity estimated using characteristic impedance increased with age in the wild-type mice, but it changed minimally in the Little mouse. We therefore conclude that arterial function in Little mice expresses a premature aging phenotype at young age and may neither enhance nor reduce their longevity.

Fifteen years of GH replacement improves body composition and cardiovascular risk factors

OBJECTIVE

Few studies have determined the effects of more than 5-10 years of GH replacement in adults on body composition and cardiovascular risk factors.

DESIGN/PATIENTS

In this prospective, single-center, open-label study, the effects of 15 years of GH replacement on body composition and cardiovascular risk factors were determined in 156 hypopituitary adults (93 men) with adult-onset GH deficiency (GHD). Mean age was 50.5 (range 22-74) years at study start. Body composition was measured using dual-energy X-ray absorptiometry.

RESULTS

The mean initial GH dose of 0.55 (S.E.M. 0.03) mg/day was gradually lowered to 0.40 (0.01) mg/day after 15 years. The mean serum IGF1 SDS increased from -1.53 (0.10) at baseline to 0.74 (0.13) at study end (P<0.001 vs baseline). Lean soft tissue (LST) increased to 3% above the baseline level at study end (P<0.001). After a 9% decrease during the first year of treatment (P<0.001 vs baseline), body fat (BF) started to increase and had returned to the baseline level after 15 years. Serum levels of total cholesterol and LDL-cholesterol decreased and serum HDL-cholesterol level increased. Fasting plasma glucose increased from 4.4 (0.1) at baseline to 4.8 (0.1) mmol/l at study end (P<0.001). However, blood HbA1c decreased from 5.0 (0.1) to 4.6 (0.1) % (P<0.001).

CONCLUSIONS

Fifteen-year GH replacement in GHD adults induced a transient decrease in BF and sustained improvements of LST and serum lipid profile. Fasting plasma glucose increased whereas blood HbA1c was reduced.

Approach to testing growth hormone (GH) secretion in obese subjects

Identification of adults with GH deficiency (GHD) is challenging because clinical features of adult GHD are not distinctive and because clinical suspicion must be confirmed by biochemical tests. Adults are selected for testing for adult GHD if they have a high pretest probability of GHD, ie, if they have hypothalamic-pituitary disease, if they have received cranial irradiation or central nervous system tumor treatment, or if they survived traumatic brain injury or subarachnoid hemorrhage. Testing should only be carried out if a decision has already been made that if deficiency is found it will be treated. There are many pharmacological GH stimulation tests for the diagnosis of GHD; however, none fulfill the requirements for an ideal test having high discriminatory power; being reproducible, safe, convenient, and economical; and not being dependent on confounding factors such as age, gender, nutritional status, and in particular obesity. In obesity, GH secretion is reduced, GH clearance is enhanced, and stimulated GH secretion is reduced, causing a false-positive result. This functional hyposomatotropism in obesity is fully reversed by weight loss. In conclusion, GH stimulation tests should be avoided in obese subjects with very low pretest probability.

Effects of Growth Hormone Administration on Muscle Strength in Men over 50 Years Old

Growth hormone (GH) use has been speculated to improve physical capacity in subjects without GH deficiency (GHD) through stimulation of collagen synthesis in the tendon and skeletal muscle, which leads to better exercise training and increased muscle strength. In this context, the use of GH in healthy elderly should be an option for increasing muscle strength. Our aim was to evaluate the effect of GH therapy on muscle strength in healthy men over 50 years old. Fourteen healthy men aged 50-70 years were evaluated at baseline for body composition and muscle strength (evaluated by leg press and bench press exercises, which focus primarily on quadriceps-lower body part and pectoralis major-upper body part-muscles, resp.). Subjects were randomised into 2 groups: GH therapy (7 subjects) and placebo (7 subjects) and reevaluated after 6 months of therapy. Thirteen subjects completed the study (6 subjects in the placebo group and 7 subjects in the GH group). Subjects of both groups were not different at baseline. After 6 months of therapy, muscle strength in the bench press responsive muscles did not increase in both groups and showed a statistically significant increase in the leg press responsive muscles in the GH group. Our study demonstrated an increase in muscle strength in the lower body part after GH therapy in healthy men. This finding must be considered and tested in frail older populations, whose physical incapacity is primarily caused by proximal muscle weakness. The trial was registered with NCT01853566.

Growth hormone, prolactin, and sexuality

GH and PRL, although not considered as 'classi cal' sexual hormones, could play a role in the endocrine control of sexual function both in men and women. Physiologically, PRL seems to be involved in the central control of sexual behavior and activity, by modulating mainly the effects of dopaminergic and serotoninergic systems on sexual function. Indeed, circulating PRL levels increase after orgasm and may potentially play a role in the acute regulation of further sexual arousal following orgasm both in men and women. On the other hand, either short-term or long-term PRL in crease can modulate central nervous system areas involved in the control of sexual function and, peripherally, can directly influence mechanisms of penile erection in men, and presently only as an hypothesis, mechanisms related to the sexual response of genitalia in women. Furthermore, chronic hyperprolactinemia is classically associated with hypogonadotropic hypogonadism and sexual dysfunction in both sexes. Successful treatment of chronic hyperprolactinemia generally restores normal sexual function both in men and women although this effect is not only related to relapse of gonadal function. Hypoprolactinemia is recently recognised as a possible risk factor of arteriogenic erectile dysfunction while a possible role on female sexual function is not known. The physiological role of GH on sexual function is not fully elucidated. GH is an important regulator of hypothalamus-pituitary-gonadal axis and seems to participate in the regulation of the sexual response of genitalia in men, and potentially also in women. Sexual function in men and women with GH deficiency (GHD) and GH excess, particularly in acromegaly, is scantily studied and GH- or IGF-I-dependent effects are difficult to quantify. Nevertheless, a decrease of desire and arousability both in men and women, together with an impairment of erectile function in men, have been described both in patients with GHD and acromegaly, although it is not clear whether they are dependent directly on the hormone defect or excess or they are consequence of the hypogonadism or the different clinical complications or the physical disfigurement and psychological imbalance, which are associated with the diseases, and are potentially affecting sexual function. Data on beneficial effects of GH replacement therapy and specific surgical or pharmacological approach for acromegaly are far to be fully elucidated although restoring normal GH/IGF-I levels have been associated to improvement of sexual function.

Hormone replacement therapy and physical function in healthy older men. Time to talk hormones?

Improving physical function and mobility in a continuously expanding elderly population emerges as a high priority of medicine today. Muscle mass, strength/power, and maximal exercise capacity are major determinants of physical function, and all decline with aging. This contributes to the incidence of frailty and disability observed in older men. Furthermore, it facilitates the accumulation of body fat and development of insulin resistance. Muscle adaptation to exercise is strongly influenced by anabolic endocrine hormones and local load-sensitive autocrine/paracrine growth factors. GH, IGF-I, and testosterone (T) are directly involved in muscle adaptation to exercise because they promote muscle protein synthesis, whereas T and locally expressed IGF-I have been reported to activate muscle stem cells. Although exercise programs improve physical function, in the long-term most older men fail to comply. The GH/IGF-I axis and T levels decline markedly with aging, whereas accumulating evidence supports their indispensable role in maintaining physical function integrity. Several studies have reported that the administration of T improves lean body mass and maximal voluntary strength in healthy older men. On the other hand, most studies have shown that administration of GH alone failed to improve muscle strength despite amelioration of the detrimental somatic changes of aging. Both GH and T are anabolic agents that promote muscle protein synthesis and hypertrophy but work through separate mechanisms, and the combined administration of GH and T, albeit in only a few studies, has resulted in greater efficacy than either hormone alone. Although it is clear that this combined approach is effective, this review concludes that further studies are needed to assess the long-term efficacy and safety of combined hormone replacement therapy in older men before the medical rationale of prescribing hormone replacement therapy for combating the sarcopenia of aging can be established.

Myths and truths of growth hormone and testosterone therapy in heart failure

Heart failure is a chronic clinical syndrome with very poor prognosis. Despite being on optimal medical therapy, many patients still experience debilitating symptoms and poor quality of life. In recent years, there has been a great interest in anabolic hormone replacement therapy - namely, growth hormone and testosterone - as an adjunctive therapy in patients with advanced heart failure. It has been observed that low levels of growth hormone and testosterone have been associated with increased mortality and morbidity in patients with heart failure. Animal studies and clinical trials have shown promising clinical improvement with hormonal supplementation. Growth hormone has been shown to increase ventricular wall mass, decrease wall stress, increase cardiac contractility, and reduce peripheral vascular resistance, all of which might help to enhance cardiac function, resulting in improvement in clinical symptoms. Likewise, testosterone has been shown to improve hemodynamic parameters via reduction in peripheral vascular resistance and increased coronary blood flow through vasodilation, thereby improving functional and symptomatic status. To date, growth hormone and testosterone therapy have shown some positive benefits, albeit with some concerns over adverse effects. However, large randomized controlled trials are still needed to assess the long-term safety and efficacy.

Multiple doses of pegylated long-acting growth hormone are well tolerated in healthy male volunteers and possess a potential once-weekly treatment profile

OBJECTIVES

Recombinant human growth hormone (rhGH) replacement therapy in children and adults currently requires daily subcutaneous injections for several years or lifelong. The current study examined safety, tolerability, pharmacokinetic and pharmacodynamic response parameters after single and multiple doses of a long-acting rhGH preparation (NNC126-0083).

DESIGN

Randomized, double-blinded, placebo-controlled, multiple-dose, dose-escalating (0·02, 0·04, 0·08 and 0·16 mg protein/kg), sequential dose group trial.

SUBJECTS

Forty adult Japanese healthy male volunteers (aged 20-45; body mass index: 18·0-27·0 kg/m(2)). Five groups (n = 8) were randomized to receive multiple doses of NNC126-0083 (n = 6) or placebo (n = 2).

METHODS

Primary outcome was safety, and tolerability of multiple doses of NNC126-0083 compared with placebo. Blood samples for the assessment of pharmacokinetics (PK) and pharmacodynamics response [insulin-like growth factor I (IGF-I) and IGF binding protein 3 (IGFBP-3)] were taken after multiple ascending doses.

RESULTS

NNC126-0083 was well tolerated and not associated with any local injection-site reactions or lipoatrophy. Following administration, NNC126-0083 levels increased rapidly and remained elevated for several days, returning to baseline before each weekly injection. Steady-state PK was achieved after the third dosing. A more than dose-proportional exposure was observed at the highest NNC126-0083 dose (0·16 mg protein/kg). A strong dose-dependent pharmacodynamic response in circulating concentrations of both IGF-I and IGFBP-3 compared with placebo (P < 0·0001) was observed during the administration of all doses.

CONCLUSIONS

Multiple administration of NNC126-0083 in healthy male volunteers indicates that NNC126-0083 has the potential for an efficacious, well-tolerated, once-weekly rhGH compound in the treatment of GH deficiency.

Cardiovascular risk, cardiac function, physical activity, and quality of life with and without long-term growth hormone therapy in adult survivors of childhood acute lymphoblastic leukemia

CONTEXT

Long-term data are missing in GH-treated acute lymphoblastic leukemia (ALL) patients. GH therapy may result in poorer outcome regarding cardiovascular (CV) and particularly cardiac effects than in patients with hypothalamic-pituitary disease.

OBJECTIVE

Our objective was to evaluate GH therapy on CV risk, cardiac function, physical activity, and quality of life in ALL patients treated with cranial radiotherapy (18-24 Gy) and chemotherapy (anthracycline dose 120 mg/m2).

DESIGN AND SETTING

We conducted a 5- and 8-yr open nonrandomized prospective study in a university hospital clinic.

STUDY PARTICIPANTS

Two groups of GH-deficient ALL patients (aged 25 yr; range 19-32 yr) and matched population controls participated.

INTERVENTIONS

One ALL group (n=16) received GH for 5 yr, and the other ALL group (n=13) did not receive GH therapy.

MAIN OUTCOME MEASURES

We evaluated the prevalence of CV risk factors and metabolic syndrome (International Diabetes Federation consensus), cardiac function (echocardiography), and quality of life and physical activity questionnaires.

RESULTS

In comparison with 8 yr without, 5 yr with GH therapy resulted in significant positive changes in plasma glucose (-0.5 vs. 0.6 mmol/liter, P=0.002), apolipoprotein B/apolipoprotein A1 ratio (-0.1 vs. 0.0, P=0.03), and high-density lipoprotein-cholesterol (0.20 vs.-0.01 mmol/liter, P=0.008) and a significant reduction in the prevalence of metabolic syndrome (P=0.008). No significant difference in the left-ventricular systolic function or in physical activity and quality of life was recorded before and after 5 or 8 yr, respectively (all P>0.3).

CONCLUSION

GH therapy reduced the CV risk in this young ALL population but resulted in no clear benefit or deterioration in cardiac function.

Mortality in patients with pituitary disease

Pituitary disease is associated with increased mortality predominantly due to vascular disease. Control of cortisol secretion and GH hypersecretion (and cardiovascular risk factor reduction) is key in the reduction of mortality in patients with Cushing's disease and acromegaly, retrospectively. For patients with acromegaly, the role of IGF-I is less clear-cut. Confounding pituitary hormone deficiencies such as gonadotropins and particularly ACTH deficiency (with higher doses of hydrocortisone replacement) may have a detrimental effect on outcome in patients with pituitary disease. Pituitary radiotherapy is a further factor that has been associated with increased mortality (particularly cerebrovascular). Although standardized mortality ratios in pituitary disease are falling due to improved treatment, mortality for many conditions are still elevated above that of the general population, and therefore further measures are needed. Craniopharyngioma patients have a particularly increased risk of mortality as a result of the tumor itself and treatment to control tumor growth; this is a key area for future research in order to optimize the outcome for these patients.