Effects of 10 years of growth hormone (GH) replacement therapy in adult GH-deficient men

Bone Quality Indices Correlate with Growth Hormone Secretory Capacity in Women Affected by Weight Excess: A Cross-Sectional Study

Background/Objectives: Obesity can be associated with impaired growth hormone (GH) secretion, with possible negative repercussions on bone health. We aimed to investigate the relationships between GH secretory capacity, evaluated with GHRH + arginine stimulation test, and bone parameters, assessed with a dual-energy X-ray absorptiometer, in a population of adult female patients affected by overweight and obesity. Methods: We assessed 276 women affected by overweight or obesity referred to the High-Specialization Center for the Care of Obesity, Umberto I Polyclinic, between 2014 and 2019 with signs or symptoms of growth hormone deficiency (GHD). Results: A total of 97 patients were diagnosed with GHD, and 179 patients with normal GH secretion were considered our control group. GHD patients showed a significantly reduced trabecular bone score (TBS) (p = 0.01). Bone quality parameters corrected for body mass index (BMI) had a positive and significant linear correlation with stimulated GH secretory capacity. Conclusions: In conclusion, bone quality, evaluated by TBS and hip structural analysis, correlates with GH-stimulated secretory capacity. GHD may act as an additive factor in the alteration of bone microarchitecture in patients affected by obesity, who are already at a higher risk of fractures.

Diagnosis and therapeutic approach to bone health in patients with hypopituitarism

The results of many studies in recent years indicate a significant impact of pituitary function on bone health. The proper function of the pituitary gland has a significant impact on the growth of the skeleton and the appearance of sexual dimorphism. It is also responsible for achieving peak bone mass, which protects against the development of osteoporosis and fractures later in life. It is also liable for the proper remodeling of the skeleton, which is a physiological mechanism managing the proper mechanical resistance of bones and the possibility of its regeneration after injuries. Pituitary diseases causing hypofunction and deficiency of tropic hormones, and thus deficiency of key hormones of effector organs, have a negative impact on the skeleton, resulting in reduced bone mass and susceptibility to pathological fractures. The early appearance of pituitary dysfunction, i.e. in the pre-pubertal period, is responsible for failure to achieve peak bone mass, and thus the risk of developing osteoporosis in later years. This argues for the need for a thorough assessment of patients with hypopituitarism, not only in terms of metabolic disorders, but also in terms of bone disorders. Early and properly performed treatment may prevent patients from developing the bone complications that are so common in this pathology. The aim of this review is to discuss the physiological, pathophysiological, and clinical insights of bone involvement in pituitary disease.

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.

Effect of long-term growth hormone replacement on glucose metabolism in adults with growth hormone deficiency: a systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis was performed to summarize the long-term (more than 6 months) effect of growth hormone (GH) replacement therapy (GHRT) on glucose metabolism among adults growth hormone deficiency (AGHD) patients.

METHODS

We searched MEDLINE, EMBASE and the Cochrane Library databases from inception till March 2020 for relevant studies evaluating the effect of GHRT on glucose metabolism in AGHD patients. Results were stratified into two periods (6-12 months and more than12 months) according to the length of follow-up.

RESULTS

Thirty-three studies including 11 randomized controlled trials (RCTs) and 22 prospective open-label studies (POLs) were included in the meta-analysis. The findings of this meta-analysis showed that GH supplementation with a duration of 6-12 months among adults with growth hormone deficiency (GHD) significantly increased fasting plasma glucose (FPG) (SMD 0.37; 95% CI 0.25 to 0.49; I² = 0%; P < 0.00001), fasting insulin (FI) (SMD 0.2; 95% CI 0.08 to 0.33; I² = 9%; P = 0.001), glycated hemoglobin (HbA1c) (SMD 0.31; 95% CI 0.17 to 0.46; I² = 10%; P < 0.0001) and homeostasis model of assessment-insulin resistance (HOMA-IR) (SMD 0.28; 95% CI 0.08 to 0.47; I² = 13%; P = 0.006). Notably, GH intervention with a duration of more than 12 months showed no significant effect on FI (SMD 0.14; 95% CI - 0.09 to 0.37; I² = 0%; P = 0.24), HbA1c (SMD - 0.02; 95% CI - 0.3 to 0.26; I² = 72%; P = 0.89) and HOMA-IR levels (SMD 0.04; 95% CI - 0.24 to 0.31; I² = 0%; P = 0.80) in adults with GHD. However, FPG levels in AGHD were still significantly increased with more than one year intervention period (SMD 0.41; 95% CI 0.29 to 0.53; I² = 0%; P < 0.00001).

CONCLUSION

Overall, the current meta-analysis demonstrated that GHRT with a shorter duration (6-12 months) led to a deterioration in glucose metabolism including FPG, FI, HbA1c and HOMA-IR in AGHD patients. However, the negative effects of GH therapy on these glucose homeostasis parameters were not seen in longer duration of GHRT, except for FPG.

Biochemical bone turnover markers in hormonal disorders in adults: a narrative review

BACKGROUND

Hormonal disorders are often associated with abnormal levels of bone turnover markers (BTMs). N-terminal propeptide of type I procollagen (PINP) and serum C-terminal cross-linking telopeptide of type I collagen (CTX-I) are the reference markers of bone formation and bone resorption, respectively.

METHODS

A comprehensive literature search within the MEDLINE and Web of Science databases was performed.

RESULTS

Acromegaly is associated with higher BTM levels, which decrease during the remission after treatment. Adult-onset growth hormone deficiency is often associated with decreased BTM levels. Growth hormone replacement therapy stimulates bone turnover and increases BTM levels. Hypothyroidism is characterized by general slowing of bone metabolism which is reflected by lower BTM levels. The replacement thyroid hormone therapy increases the bone turnover rate and BTM levels increase. Patients with thyroid cancer receive a suppressive dose of thyroid hormones and may have slightly elevated BTM levels. Patients with overt hyperthyroidism had higher BTM levels and anti-thyroid therapy induces a rapid decrease in the BTM levels. Patients with overt primary hyperparathyroidism have higher BTM levels, whereas those with asymptomatic and normocalcemic hyperparathyroidism usually have normal BTM levels. Hypoparathyroidism is characterized by slightly decreased BTM levels. Cushing's syndrome is characterized consistently by markedly decreased osteocalcin concentration, whereas data on other BTMs are discordant.

CONCLUSIONS

BTMs help us to better understand mechanisms of the impact of hormonal disorders and their treatment on bone metabolism. However, it is unknown whether BTMs may be used to monitor the effect of their treatments on bone in the clinical practice.

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.

Pituitary Diseases and Bone

Neuroendocrinology of bone is a new area of research based on the evidence that pituitary hormones may directly modulate bone remodeling and metabolism. Skeletal fragility associated with high risk of fractures is a common complication of several pituitary diseases such as hypopituitarism, Cushing disease, acromegaly, and hyperprolactinemia. As in other forms of secondary osteoporosis, pituitary diseases generally affect bone quality more than bone quantity, and fractures may occur even in the presence of normal or low-normal bone mineral density as measured by dual-energy X-ray absorptiometry, making difficult the prediction of fractures in these clinical settings. Treatment of pituitary hormone excess and deficiency generally improves skeletal health, although some patients remain at high risk of fractures, and treatment with bone-active drugs may become mandatory. The aim of this review is to discuss the physiological, pathophysiological, and clinical insights of bone involvement in pituitary diseases.

Update on GH therapy in adults

Over the last three decades, short- and long-term observational studies, clinical trials, systematic reviews, and meta-analyses have provided relevant information on the efficacy and safety of growth hormone (GH) replacement therapy in adults with GH deficiency (AGHD). The knowledge acquired during this time has been compiled into different guidelines that offer clinicians an evidence-based, practical approach for the management of AGHD. There are, however, still open questions in some key areas in which recommendations are supported by only moderate or weak evidence. In the last recent years, the development of long-acting GH preparations has created new therapeutic possibilities by decreasing injection frequency, improving adherence and thereby potentially maximizing clinical outcomes. The aims of this review are to advance our understanding on the diagnosis and treatment of AGHD and to present an update and future perspectives on the use of long-acting GH preparations.

Comparison of low-normal and high-normal IGF-1 target levels during growth hormone replacement therapy: A randomized clinical trial in adult growth hormone deficiency

BACKGROUND

Current guidelines state that the goals of growth hormone (GH) therapy in adults should be an appropriate clinical response, avoidance of side effects, and an IGF-1 value within the age-adjusted reference range. There are no published studies on the target level for IGF-1 that offer specific guidance in this regard.

OBJECTIVES

To compare low-normal and high-normal target levels of IGF-1 on efficacy and safety of GH treatment.

METHODS

A randomized, open-label, clinical trial including thirty-two adults from one university hospital receiving GH therapy for at least one year with a stable IGF-1 concentration between -1 and 1 SD score (SDS). Subjects were randomized to receive either a decrease (IGF-1 target level of -2 to -1 SDS) or an increase of their daily GH dose (IGF-1 target level of 1 to 2 SDS) for a period of 24weeks. The effect on cardiovascular risk factors and physical performance, next to tolerability, was compared.

RESULTS

Thirty subjects (65.6% men, mean age 46.6 (SD 9.9) years) could be analyzed. In subjects with a high-normal IGF-1 target level, waist circumference decreased (p=0.05), and overall they felt better (p=0.04), compared to subjects with a low-normal IGF-1 target level. However, increasing IGF-1 levels led to more myalgia, and decreasing IGF-1 levels to more fatigue. There was a gender-dependent difference in effect on HDL cholesterol.

CONCLUSION

Although increasing GH dose to IGF-1 levels between 1 and 2 SDS improved waist circumference and well-being, safety was not guaranteed with the demonstrated effect on HDL cholesterol in men, and reported myalgia.

Effects of recombinant human growth hormone therapy on bone mineral density in adults with growth hormone deficiency: a meta-analysis

OBJECTIVE

GH deficiency is associated with decreased bone mineral density (BMD) and increased fracture risk. Because the effects of recombinant human GH (rhGH) therapy on BMD and bone mineral content have not been systematically investigated, we conducted a meta-analysis of pertinent studies.

DESIGN

A thorough search of the literature (MEDLINE, EMBASE, and the Cochrane Register) was performed. Relevant studies were divided and analyzed according to their design (randomized/controlled or prospective/retrospective) and duration of rhGH therapy (≤12 months and > 12 months).

RESULTS

Administration of rhGH led to a significant increase in lumbar spine (LS) and femoral neck (FN) BMD in randomized/controlled studies of more than 1 year [weighted mean difference (95% confidence interval)] of 0.038 g/cm(2) (0.011-0.065) and 0.021 g/cm(2) (0.006-0.037) at the LS and FN, respectively, and a nonsignificant drop at the same sites in studies of shorter duration. In prospective studies, a significant increase in the LS and FN BMD was obtained. On meta-regression, a negative association was observed between the change in LS and FN BMD and subjects' age and a positive association between the BMD change and treatment duration. In a subgroup analysis, the increase in LS and FN BMD was significant in men [0.048 g/cm(2) (0.033-0.064) and 0.051 g/cm(2) (0.003-0.098), respectively] but not in women.

CONCLUSION

This meta-analysis suggests a beneficial effect of rhGH replacement on BMD in adults with GH deficiency. This effect is affected by gender, age, and treatment duration. Larger studies are needed to evaluate the effect of rhGH on fracture risk.

Impact of the growth hormone replacement on bone status in growth hormone deficient adults

INTRODUCTION

Growth hormone deficiency (GHD) is associated with reduced bone mineral density (BMD). GH replacement has positive effect on BMD but the magnitude of this effect and its mechanism are debated.

OBJECTIVES

The objectives of this study was first, to assess the effect of GH replacement on BMD, and second, to evaluate the effect of GH treatment on bone turnover and microarchitecture and to assess the factors influencing the effect of the therapy on BMD.

PATIENTS AND METHODS

Adult GHD (AO-GHD) and childhood onset GHD (CO-GHD) patients treated with GH using IGF-I normalization GH replacement regimen were prospectively followed during 2 years. Lumbar spine (L1-L4) and total femur BMD by Hologic discovery, in the subset of patients also bone turnover markers; osteocalcin and carboxy-terminal collagen crosslinks (CTx) were assessed at baseline and at months 3, 6, 12 and 24, respectively. The trabecular bone score (TBS) derived from lumbar spine DXA by the iNsight® software was assessed in a subset of study population at baseline and months 12 and 24.

RESULTS

In total, 147 GHD patients (age 35.1 years, 84 males/63 females, 43 of childhood onset GHD/104 AO-GHD) were included. BMD of lumbar spine and femur increased significantly during the treatment (14% and 7% increase at 2 years, respectively; p<0.0001). Bone markers increased during the first 12 months of treatment with subsequent decrease of CTx. At month 24, significant increase in TBS was observed (4%, p=0.02). BMD increase was significantly higher in males (15% increase in males vs. 10% in females, p=0.037) and childhood onset GHD (CO-GHD) patients (13% increase in CO-GHD, p=0.004).

CONCLUSION

GH supplementation leads to an increase of BMD with corresponding changes in bone turnover markers and changes in microarchitecture as assessed by trabecular bone score. Positive effect of GH on bone status is more pronounced in males and CO-GHD adults.

Predictors of the effects of 4 years of growth hormone replacement on bone mineral density in patients with adult-onset growth hormone deficiency - a KIMS database analysis

OBJECTIVE

Growth hormone (GH) replacement may increase bone mineral density (BMD) in GH-deficient (GHD) adults. The goal of this study was to identify predictors of BMD response to GH replacement in GH naïve adults.

DESIGN AND MEASUREMENTS

This was a retrospective analysis of data extracted from KIMS (Pfizer International Metabolic Database), an international pharmacoepidemiological survey of adult GHD patients from 31 countries.

PATIENTS

A total of 231 GH naive adults were identified (115 women and 116 men) who had BMD measured on the same densitometer in the lumbar spine (LS) and/or femoral neck (FN) both at baseline and after 4 years of GH replacement.

RESULTS

After 4 years, there was a median (10th, 90th percentile) 4·6% (-5·2%, 12·2%) increase in LS BMD over baseline (P = 0·0001). There was a positive correlation between per cent change in LS BMD and age at the onset of pituitary disease (r = 0·25, P = 0·001). There was no change in FN BMD over baseline [0·0% (-7·3%, 8·5%)]. On multivariate analysis, older age at the onset of pituitary disease predicted a greater increase in LS BMD on GH replacement (r = 0·55, P < 0·0001).

CONCLUSIONS

In a population of GH naïve adults, GH replacement led to a significant increase in LS BMD over baseline, but no change in FN BMD. The potential for greater BMD improvement on GH replacement therapy in adults with disease of later onset should be considered when making treatment decisions in this patient population.

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.

Effects of growth hormone replacement therapy on bone mineral density in growth hormone deficient adults: a meta-analysis

Objectives. Growth hormone deficiency patients exhibited reduced bone mineral density compared with healthy controls, but previous researches demonstrated uncertainty about the effect of growth hormone replacement therapy on bone in growth hormone deficient adults. The aim of this study was to determine whether the growth hormone replacement therapy could elevate bone mineral density in growth hormone deficient adults. Methods. In this meta-analysis, searches of Medline, Embase, and The Cochrane Library were undertaken to identify studies in humans of the association between growth hormone treatment and bone mineral density in growth hormone deficient adults. Random effects model was used for this meta-analysis. Results. A total of 20 studies (including one outlier study) with 936 subjects were included in our research. We detected significant overall association of growth hormone treatment with increased bone mineral density of spine, femoral neck, and total body, but some results of subgroup analyses were not consistent with the overall analyses. Conclusions. Our meta-analysis suggested that growth hormone replacement therapy could have beneficial influence on bone mineral density in growth hormone deficient adults, but, in some subject populations, the influence was not evident.

Peripheral bone mineral density in correlation to disease-related predisposing conditions in patients with multiple endocrine neoplasia type 1

BACKGROUND AND AIM

Patients with multiple endocrine neoplasia type 1 (MEN1) often have low bone mineral density (BMD) attributed to primary hyperparathyroidism (pHPT). However, in MEN1 patients, other endocrine dysfunctions and conditions such as hypercortisolism, hypogonadism, and GH deficiency due to pituitary manifestation, and surgery on the upper gastrointestinal tract may affect BMD.

SUBJECTS AND METHODS

In 23 patients with MEN1 (10 females, 13 males; 46±12 yr), BMD was determined by quantitative computed tomography at the forearm (pqCT), compared to a reference population and related to different conditions suspected to affect bone metabolism in MEN1.

RESULTS

In this cohort, Z-score for trabecular BMD was -0.85±1.18 and for total BMD -1.16±1.04. There was a similar trend towards lower BMD in uncontrolled hyperparathyroidism, hypercortisolism, hypogonadism/GH deficiency and the state after surgery at the upper gastrointestinal tract.

CONCLUSIONS

These data while confirming previous observations on reduced BMD in patients with MEN1, however, challenge its only or even predominant association with pHPT. Other conditions such as hypercortisolism, somatotrophic/ gonadotrophic pituitary insufficiency, and previous upper gastrointestinal surgery seem to be factors contributing to the risk of developing osteoporosis.

Rationale and design of PATRO Adults, a multicentre, noninterventional study of the long-term efficacy and safety of Omnitrope(®) for the treatment of adult patients with growth hormone deficiency

OBJECTIVE

To describe the rationale and design of PATRO Adults, a postmarketing surveillance study of the long-term efficacy and safety of somatropin (Omnitrope(®)) for the treatment of adult patients with growth hormone deficiency (GHD).

METHODS

PATRO Adults is an observational, multicentre, open, longitudinal, noninterventional study being conducted in hospitals and specialized endocrinology clinics across several European countries. The primary objective is to assess the safety and efficacy of Omnitrope(®) in adults treated in routine clinical practice. Eligible patients are male or female adults who are receiving treatment with Omnitrope(®) and who have provided informed consent. Patients who have been treated with another human growth hormone (hGH) product before starting Omnitrope(®) therapy will also be eligible for inclusion. Efficacy assessments will be based on the analysis of the following: insulin-like growth factor-1 levels within age- and gender-adjusted normal ranges; anthropometric measures (weight, waist circumference, total fat mass, lean body mass, total body water); bone mineral density; lipids; effects on cardiovascular risk factors such as glucose metabolism, blood pressure and inflammatory markers (e.g. C-reactive protein); and quality of life. All adverse events will be monitored and recorded. Particular emphasis will be placed on long-term safety, the recording of malignancies, the occurrence and clinical impact of antirecombinant hGH antibodies, the incidence, severity and duration of hyperglycaemia, and the development of diabetes during treatment with Omnitrope(®).

CONCLUSIONS

PATRO Adults is a large, long-term, postmarketing surveillance study that will extend the safety database for Omnitrope(®), as well as contributing to the available data for all recombinant hGH products. Of particular interest, the study will provide important data on the impact of long-term GH replacement therapy on the development of diabetes mellitus, the recurrence/regrowth of hypothalamic-pituitary tumours, and de novo malignancy or recurrence of other (non-hypothalamic-pituitary) tumours.

The effect of polyethylene glycol recombinant human growth hormone on growth and glucose metabolism in hypophysectomized rats

OBJECTIVE

To study the effect of polyethylene glycol recombinant human growth hormone on growth and glucose metabolism in hypophysectomized rats, and compare the effect of treatment between recombinant human growth hormone (rhGH) and polyethylene glycol rhGH (PEG-rhGH).

METHODS

Hypophysectomy was performed in juvenile rats to build the animal model of GH deficiency. The hypophysectomized animals were randomly assigned into three groups and treated with saline (negative control, n=20), rhGH (n=20) and PEG-rhGH (n=20). A sham operation was performed to set up the normal control (n=20). Body weight, body length and tail length were recorded every 2days for a 14-day treatment and bone growth was measured at the end of therapy. Glucose infusion rate (GIR) determined by euglycemic hyperinsulinemic clamp was used to evaluate insulin sensitivity after GH treatment. We also examined plasma glucose and serum insulin levels

RESULTS

Compared with the negative control, the body weight, body length, tail length and bone growth increased significantly in hypophesectomized rats treated by GH (P<0.01). Although the weight gain in the first 10days was higher in the PEG-rhGH group than in the rhGH group (P<0.05), the growth promoting effect was similar between rhGH and PEG-rhGH (P>0.05). Neither rhGH nor PEG-rhGH impaired glucose tolerance of rats after hypophesectomy. Compared with negative controls, according to decreased serum insulin, reduced insulin expression in pancreatic cells and increased GIR in the clamp, both rhGH and PEG-rhGH groups had improved insulin sensitivity within 14 days (P<0.01). However, with prolonged treatment, the GIR in the rhGH-treated rats decreased significantly (P<0.05); while PEG-rhGH did not interfere with GIR, even after a doubled dose (P>0.05).

CONCLUSIONS

PEG-rhGH had the same linear growth promoting efficacy as unmodified rhGH. The short-term GH replacement could improve insulin sensitivity in hypophysectomized rats, especially after PEGylation.

Favorable long-term effects of growth hormone replacement therapy on quality of life, bone metabolism, body composition and lipid levels in patients with adult-onset growth hormone deficiency

OBJECTIVE

The goal of growth hormone (GH) replacement is to improve quality of life (QoL) and prevent the long-term complications of GH deficiency (GHD). Thirty-nine patients with adult-onset GH deficiency (AOGHD) who had originally participated in a randomized placebo-controlled crossover study involving treatment with either GH or placebo for nine months were enrolled in an open, 33-month follow-up study of the effects on QoL as well as bone and metabolic parameters.

METHODS

GH replacement was dosed individually to obtain IGF-I concentrations that were within the upper part of the normal range for age (mean+1SD). The variables were assessed on five occasions during the study.

RESULTS

QoL, as assessed by the sum scores of HSCL-58, AGHDA, physical activity (KIMS question 11) and the dimension vitality in SF-36, improved. Markers of bone formation and resorption remained increased throughout the study period. Bone mineral area (BMA), bone mineral content (BMC) and bone mineral density (BMD) increased in both the lumbar (L2-L4) spine and total body. BMC and BMD increased in the femur. Hypogonadal women however, showed reduced bone mass during the study period. The changes in body fat mass (BFM) and lean body mass (LBM) were sustained throughout the long-term treatment (BFM -2.18 (+/-4.87) kg LBM by 2.01(+/-3.25) kg). Low-density lipoprotein cholesterol (LDL-C) levels were reduced by 0.6 (+/-1.1) mmol/l, and high-density lipoprotein cholesterol (HDL-C) levels increased by 0.2 (+/-0.3) mmol/l. No changes were observed in body weight, fasting total cholesterol, triglycerides, HbA1c and plasma glucose. Mean fasting insulin levels increased significantly from 110 pmol/l to 159 pmol/l, p<0.02.

CONCLUSION

Long-term replacement of growth hormone in patients with AOGHD induces favorable effects on QoL as well as bone and metabolic parameters. An increase in insulin levels is also noteworthy.

Improved insulin sensitivity, preserved beta cell function and improved whole-body glucose metabolism after low-dose growth hormone replacement therapy in adults with severe growth hormone deficiency: a pilot study

AIMS/HYPOTHESIS

Growth hormone-deficient patients show deterioration of insulin sensitivity and beta cell function. High-dose growth hormone treatment often induces further impairment of insulin sensitivity, leading to an increase in insulin and glucose levels or even, in cases of preexisting beta cell defect, to overt diabetes. However, low-dose treatment may improve insulin sensitivity, although data in humans with detailed metabolic phenotyping are as yet not available. We postulated that long-term low-dose growth hormone replacement, restoring IGF-1 to the low-normal range, might beneficially affect glucose metabolism.

METHODS

We studied prospectively the metabolic responses to 24 and 48 weeks of growth hormone treatment in a small group of six adults with severe growth hormone deficiency (four men, two women; age 40-59 years; BMI 30.2 +/- 1 kg/m(2); mean growth hormone dose 0.3 +/- 0.04 mg/day). All participants underwent an oral glucose tolerance test, euglycaemic-hyperinsulinaemic clamp and hyperglycaemic-hyperinsulinaemic clamp plus i.v. L: -arginine on three occasions. Insulin sensitivity was measured by calculating the M value during the steady state of the euglycaemic-hyperinsulinaemic clamp. Insulin secretion and clearance were estimated from AUC(C-peptide), AUC(insulin) and their ratio at each phase of the hyperglycaemic-hyperinsulinaemic clamp.

RESULTS

Growth hormone significantly improved insulin sensitivity (M value 13.8 +/- 2.6 [baseline] vs 19.6 +/- 2.6 [24 weeks] and 23.7 +/- 1.9 [48 weeks] micromol kg(-1) min(-1); p < 0.01). Although the insulin response to glucose and arginine decreased slightly, the disposition index, integrating insulin sensitivity and secretion, significantly increased (p < 0.01), indicating an improvement in whole-body glucose metabolism. Insulin clearance was not affected during treatment (p > 0.05).

CONCLUSIONS/INTERPRETATION

Our data indicate that long-term low-dose growth hormone treatment may improve insulin sensitivity and whole-body glucose metabolism in adults with severe growth hormone-deficiency.

The influence of growth hormone replacement on peripheral inflammatory and cardiovascular risk markers in adults with severe growth hormone deficiency

BACKGROUND

Adult GHD syndrome is associated with clustering of adverse cardiovascular (CV) risk factors such as abnormal body composition, dyslipidemia, insulin resistance and abnormal haemostatic factors. There is a wealth of evidence linking CV events with elevated levels of inflammatory markers (hs-CRP and IL-6) in the general population; however data on their abnormalities in GHD and specially the effects of GH replacement (GHR) on these inflammatory markers are limited.

OBJECTIVE

To study the effects of GHR on inflammatory markers, glucose homeostasis and body composition in a cohort of adults with recently diagnosed severe GHD due to hypothalamic pituitary disease.

DESIGN

Fifteen hypopituitary adults (11 males, mean age 48.5 years) with recently diagnosed, severe GHD were recruited. Patients received GHR (in addition to other pituitary hormone replacements) titrated to clinical response and to normalize age and gender adjusted IGF-1 levels. Weight, waist hip ratio (WHR), body composition, fasting plasma glucose and insulin, insulin resistance index (HOMA-IR), fasting serum lipid levels, hs-CRP, IL-6 and TNF-alpha were measured at baseline and following a minimum 6 months of stable maintenance GHR.

RESULTS

GHR resulted in a physiological increase in IGF-1 SDS [median -0.6 to +0.39, P<0.0001], improved quality of life (mean pre-treatment AGHDA score 16 vs. post-treatment score 7, P<0.0001) and reduction in WHR (0.94 vs. 0.92, P=0.01). There were no significant changes in body weight and composition. Levels of hs-CRP (log transformed, mean (SD)) were significantly reduced following GHR (pre 1.21 (0.9) vs. post 0.27 (0.9), P<0.0001) but TNF-alpha and IL-6 levels remained unchanged. Fasting glucose (mmol/L) [4.6 (0.1) vs. 5.1 (0.1), P=0.003], fasting insulin (muU/mL) [9.4 (8.1) vs. 12.1 (9.2), P=0.03] and HOMA-IR [1.2 (1.0) vs. 1.5 (1.1) P=0.02] (all pre-GHR vs. post-GHR and mean (SD)) significantly increased following GHR indicating increased insulin resistance. Significant improvements were noted in fasting LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) levels following GHR [3.4 (0.9) vs. 2.9 (0.7), P=0.03 and 1.2 (0.2) vs. 1.3 (0.2), P=0.02, respectively] (all pre-GHR vs. post-GHR and mean (SD)). Levels of total cholesterol and triglycerides did not change following GHR.

CONCLUSIONS

Physiological GHR for at least 6 months in hypopituitary adults with recently diagnosed severe GHD resulted in favourable changes in hs-CRP, WHR, fasting LDL-C and HDL-C levels all of which are recognised CV risk markers. However, there remains a high prevalence of obesity in this population and given the worsening of insulin sensitivity in the short term with GHR, monitoring and aggressive treatment of established CV risk factors is essential to reduce premature atherosclerotic CVD in this patient population.

Comparison of glucose and lipid metabolism and bone mineralization in patients with growth hormone deficiency with and without long-term growth hormone replacement

The effects of long-term growth hormone (GH) substitution in pituitary-insufficient patients with GH deficiency (GHD-pats) on glucose and lipid metabolism and bone mineral density (BMD) have yet to be ascertained. We performed this cross-sectional study comparing GHD-pats with and without long-term GH substitution. We measured lipid parameters at baseline and glucose and insulin concentrations for 3 hours during oral glucose tolerance test in 52 GHD-pats (21 female and 31 male; median age, 51.5 years [27-82]). Twenty-two GHD-pats were on constant GH substitution (GH-Subs) for a median of 10 years (2-42 years). Thirty GHD-pats had not been substituted for at least 2 years (non-Subs). For analyses of beta-cell function, insulin resistance (IR), and sensitivity, homeostatic model assessment (HOMA)-beta , HOMA-IR, and insulin sensitivity index were used, respectively. Body composition and BMD were measured by dual-energy x-ray absorptiometry. Age and body mass index did not differ significantly between groups. Fasting glucose was significantly lower for GH-Subs than non-Subs (87 mg/dL [71-103] vs non-Subs 89 mg/dL [71-113], P < .05), whereas basal insulin did not differ significantly (10 muU/mL (4-42) vs non-Subs 10 microU/mL [4-63]). Glucose and insulin levels at 120 minutes as well as patients' area under the curve, C-peptide, hemoglobin A(1c), waist-hip ratio, HOMA-beta, HOMA-IR, insulin sensitivity index, lipid parameters, and BMD did not differ significantly; but total fat mass was significantly higher in non-Subs (37% [20%-52%] vs GH-sub 31% [13%-54%], P < .01). More non-Subs had abnormal glucose tolerance (19 [63%] vs GH-Subs 9 [41%]). Long-term GH substitution trends to beneficially influence fasting glucose and glucose tolerance, although differences are sparse. Growth hormone substitution alone does not seem to significantly impact on insulin sensitivity, lipid metabolism, and BMD in patients with pituitary insufficiency.

Treatment of adult growth hormone deficiency: who, why and how? A review

Adult growth hormone deficiency (AGHD) is nowadays recognized as a distinct clinical entity and replacement therapy has become a standard practice. Reflecting on the accumulated evidence, questions nevertheless arise. Should all AGHD patients be treated? What dose of GH should be given and for how long? What are the real long-term benefits, in particular regarding life expectancy? if the diagnosis of severe GHD is firmly established and if there is no contra-indication (such as an active cancer or uncontrolled diabetes), it is worthwile initiating GH replacement therapy. Treatment can indeed correct the abnormal body composition, improve various adverse cardiovascular parameters and risk factors, increase muscle strength and bone mineral density and, although to a variable degree, improve the patient's quality of life and psychological well-being. Treatment should be started with very low doses to avoid side-effects related to fluid retention and should then be gradually titrated against IGF-I values, clinical response and individual tolerance.There is unfortunately no confirmed predictive factor for the overall therapeutic response in a given individual. Thus, the decision to whether or not pursue the therapy will depend on the ratio of perceived and expected benefits over cost and risks of treatment, as well as on the persistent motivation of the patient.

Growth hormone and bone

PURPOSE OF REVIEW

Description of recent progress in our understanding of growth hormone (GH) effects on bone.

RECENT FINDINGS

Growth hormone deficiency is associated with low bone mass in children and adults, in addition to its well established impact on growth. Although GH and insulin-like growth factor I have direct skeletal actions, it is also possible that disordered parathyroid hormone secretion or effect may mediate some of the deleterious consequences of GH deficiency on bone. The benefits of GH replacement on bone mineral density have been demonstrated in many studies, but it remains unclear whether these are consistent across patient subgroups. The impact of GH replacement on fracture risk has not been definitively established. The positive effects of GH administration on growth are well established in childhood-onset growth hormone deficiency, as well as in several other pediatric conditions. Data on investigational uses of GH are also presented.

SUMMARY

GH may have a relevant role in bone physiology and several disease states in addition to growth hormone deficiency. Although the salutary effects of GH replacement on bone growth and bone density are well characterized, additional studies are required to examine the impact of GH replacement on fracture risk as well as potential benefits in osteoporosis.

[Efficacy, safety and compliance of long-term growth hormone (GH) replacement therapy in adults with GH deficiency]

AIM

To study efficacy, safety and compliance of GH therapy for 4 years in 18 GH deficient (GHD) adults [12 women; mean age 50.5 yrs (25-66 yrs)].

METHODS

Clinical, biochemical and body composition (DXA) measurements were performed before and every year after GH therapy. Ecocardiography was performed at baseline and after 4 years. Dose of GH was 0.2 mg/day during the first year with subsequent titration to attain normal IGF-1 levels.

RESULTS

There was a significant reduction of total body fat (mean 2.8 kg), truncal fat (mean 1.9 kg) and an increase of lean body mass (mean 0.8 kg) and bone mineral density (BMD) on lumbar spine and femur, particularly in sites with T-score<-1,0 at baseline. Insulin levels and HOMA index worsened in the first year, but at the end no changes were noted on glucose, insulin, HOMA index and glycosylated hemoglobin. Two patients with altered glucose tolerance at baseline developed type 2 diabetes during follow-up. Total and LDL-cholesterol were significantly lower after therapy, with changes directly associated with baseline values. Cardiac parameters did not change. Side effects were mild and disappeared spontaneously. Tumor recurrence was not observed. Low compliance (estimated by low IGF-1 levels) was observed in 4 (22%), 2 (11%) and 6 (33%) patients at the end of second, third and fourth year, respectively.

CONCLUSIONS

Four years of GH therapy in GHD adults had a positive impact on body composition, BMD and lipid profile, with no effects on insulin sensitivity and heart. Glucose tolerance should be monitored carefully during long-term GH therapy.

Treatment for 24 months with recombinant human GH has a beneficial effect on bone mineral density in young adults with childhood-onset GH deficiency

OBJECTIVE

Discontinuation of growth hormone (GH) therapy on completion of linear growth may adversely affect bone mineral density (BMD) in young adults with childhood-onset GH-deficiency (GHD). In the present study, we analyzed the impact of GH treatment on bone in young adults with GHD.

METHODS

BMD at the lumbar spine (L2-L4), total hip, and total body was measured at baseline and after 24 months in a cohort of young adults (18-25 years; n=160) with severe GHD treated with GH during childhood who were randomized to GH (n=109) or no treatment (n=51) in a multicenter, multinational, open-label study. GH starting doses (0.2 mg/day (males), 0.4 mg/day (females)) were increased after 1 month to 0.6 mg/day (males) and 0.9 mg/day (females) and then to 1.0 mg/day (males) and 1.4 mg/day (females) at 3 months for the remainder of the study.

RESULTS

After 24 months, lumbar spine BMD had increased significantly more in GH-treated patients than in controls (6 vs 2%; estimated treatment difference; 3.5% (95% confidence interval, 1.52-5.51) P<0.001). GH also had a significant positive effect on total hip BMD (P=0.015). Total body BMD was unchanged from baseline (P=0.315).

CONCLUSIONS

In young adults treated for childhood-onset GHD, there is a beneficial effect of continued GH treatment on BMD in adult life. Twenty-four months of GH treatment in these young adults was associated with an estimated 3.5% greater increase in BMD of the lumbar spine compared with controls.

Growth hormone, insulin-like growth factors, and the skeleton

GH and IGF-I are important regulators of bone homeostasis and are central to the achievement of normal longitudinal bone growth and bone mass. Although GH may act directly on skeletal cells, most of its effects are mediated by IGF-I, which is present in the systemic circulation and is synthesized by peripheral tissues. The availability of IGF-I is regulated by IGF binding proteins. IGF-I enhances the differentiated function of the osteoblast and bone formation. Adult GH deficiency causes low bone turnover osteoporosis with high risk of vertebral and nonvertebral fractures, and the low bone mass can be partially reversed by GH replacement. Acromegaly is characterized by high bone turnover, which can lead to bone loss and vertebral fractures, particularly in patients with coexistent hypogonadism. GH and IGF-I secretion are decreased in aging individuals, and abnormalities in the GH/IGF-I axis play a role in the pathogenesis of the osteoporosis of anorexia nervosa and after glucocorticoid exposure.

[Growth hormone deficiency in adulthood: how to diagnose and when to treat?]

Adult growth hormone deficiency (AGHD) is a well-established clinical entity with heterogeneous characteristics, in which the main causes are hypothalamus-pituitary tumors and/or their treatment. The diagnosis of ADGH should be considered in patients with a prior history of childhood-onset GH deficiency or a history of organic hypothalamus-pituitary disease. In these patients diagnosis is performed biochemically by provocative tests of GH secretion, once the measurement of the biological markers for GH action:IGF-l and IGFBP-3 levels, can be in the normal range in an important percentage of AGHD patients. The current treatment using an initial low dose of hrGH followed by individualised dose titration adjusted according to serum IGF-1 levels, leads to similar beneficial effects with less incidence of side effects, improved tolerance to treatment and a lower stable GH dose as compared to hrGH replacement therapy based on body weight or body surface area. As some patients might not profit from hrGH therapy, the potential beneficial effects of hrGH replacement therapy should be analyzed on individualized basis. Alternative available therapies with similar efficacy should be taken into consideration. Physical activity may improve body compostion, cardiovascular perfomance and well being in ADGH subjects not submitted to hrGH treatment. An important target of hrGH replacement therapy is its impact on quality of life, leading to social and professional improvement. Epidemiological evidence points to a decreasing life expectancy in ADGH patients but data regarding the impact of hrGH replacement on life expectancy are still lacking.

GH replacement reduces increased lipid peroxidation in GH-deficient adults

BACKGROUND

GH replacement improves numerous metabolic abnormalities in GH-deficient patients; increased lipid peroxidation (LPO) has been observed in GH-deficient patients; however, it is unknown if LPO is influenced by GH replacement.

AIM AND METHODS

To evaluate the extent to which GH replacement might reverse the increased LPO in GH-deficient adults and to analyse if this phenomenon might be involved in the improvement of metabolic disturbances due to GH treatment. Serum concentrations of malondialdehyde + 4-hydroxyalkenals (MDA + 4-HDA), as an index of LPO, were measured at baseline, and after 12 and 24 months of GH replacement in 40 adult patients with severe GH deficiency (both in adult- and childhood-onset) and in 40 healthy volunteers, matched for sex, age and body mass index (BMI). Correlations were evaluated between LPO and lipids, IGF-I, metalloproteinase-2 and -9 (MMP-2, -9), vascular endothelial growth factor (VEGF), BMI and GH dose.

RESULTS

LPO values in GH-deficient patients were several-fold higher than in controls [55.36 +/- 2.27 vs. 4.19 +/- 0.42 nmol/mg protein (mean +/- SEM), P < 0.0001] and decreased significantly over time with GH replacement to 38.61 +/- 2.15 nmol/mg protein (i.e. by approximately 30%), though still remaining markedly elevated compared with controls (P < 0.0001). The proatherogenic lipid profile parameters correlated positively with LPO in the childhood-onset subgroup before GH replacement. GH replacement restored the positive correlation between LPO and age in male patients (r = 0.57, P = 0.013; r = 0.8, P < 0.001, at 12 and 24 months of GH replacement, respectively).

CONCLUSIONS

GH replacement partially reverses the grossly abnormal LPO in GH-deficient adults. It is highly probable, therefore, that oxidative mechanisms are involved in the overall improvement of metabolic changes due to GH replacement.

Management of growth hormone deficiency in adults

Growth hormone (GH) deficiency in adults is a recognised clinical entity. There is still, however, an ongoing debate of the clinical need and the importance of replacing GH in adults with severe GH deficiency. This review will focus on the overall management of adults with GH deficiency and highlight published data on dose management and treatment goals for various age groups. The efficacy data on quality of life and well-being is discussed and available and growing experience on long-term effects of GH replacement in adults and safety in terms of diabetes mellitus, pituitary tumour recurrence/regrowth and malignancy risk will be reviewed.

Anterior pituitary hormone replacement therapy--a clinical review

This clinical review summarizes current approaches to diagnosis and treatment of anterior pituitary hormone deficiency. The diagnostic value of endocrine function tests and replacement strategies for hydrocortisone, thyroxine, sex steroids, and growth hormone replacement are reviewed. Female androgen deficiency syndrome and the current role of DHEA and testosterone replacement in women are also discussed.

Therapeutic aspects of growth hormone and insulin-like growth factor-I treatment on visceral fat and insulin sensitivity in adults

Growth hormone (GH) is generally considered to exert anti-insulin actions, whereas insulin-like growth factor I (IGF-I) has insulin-like properties. Paradoxically, GH deficient adults and those with acromegaly are both predisposed to insulin resistance, but one cannot extrapolate from these pathological conditions to determine the normal metabolic roles of GH and IGF-I on glucose homeostasis. High doses of GH treatment have major effects on lipolysis, which plays a crucial role in promoting its anti-insulin effects, whereas IGF-I acts as an insulin sensitizer that does not exert any direct effect on lipolysis or lipogenesis. Under physiological conditions, the insulin-sensitizing effect of IGF-I is only evident after feeding when the bioavailability of circulating IGF-I is increased. In contrast, many studies in GH deficient adults have consistently shown that GH replacement improves the body composition profile although these studies differ considerably in terms of age, the presence or absence of multiple pituitary hormone deficiency, and whether GH deficiency was childhood or adult-onset. However, the improvement in body composition does not necessarily translate into improvements in insulin sensitivity presumably due to the anti-insulin effects of high doses of GH therapy. More recently, we have found that a very low dose GH therapy (0.1 mg/day) improved insulin sensitivity without affecting body composition in GH-deficient adults and in subjects with metabolic syndrome, and we postulate that these effects are mediated by its ability to increase free 'bioavailable' IGF-I without the induction of lipolysis. These results raise the possibility that this low GH dose may play a role in preventing the decline of beta-cell function and the development of type 2 diabetes in these "high risk" subjects.

Bone mineral density in patients with growth hormone deficiency: does a gender difference exist?

OBJECTIVE

The aim of the study was to clarify whether a gender difference exists with respect to bone mineral density (BMD) and bone mineral content (BMC) in adult patients with growth hormone deficiency (GHD).

DESIGN

A case-control design.

METHODS

Blood sampling for measurements of calcium, phosphate, creatinine, PTH, vitamin D, IGF-1, markers of bone formation and bone resorption, and dual energy X-ray absorptiometry (DEXA), to determine BMD and BMC of the lumbar spine, hip, distal arm and total body, were performed in 34 patients with GHD (19 females) and 34 sex-, age- and weight-matched healthy control subjects. The patients were well substituted on all pituitary axes, apart from GH.

RESULTS

GH-deficient males had significantly lower BMD in the lumbar spine (P = 0.02), hip (P = 0.01) and total body (P = 0.003) than healthy males while GH-deficient females compared to healthy females had identical BMD values at all regions. This gender difference was even more obvious when BMD values were expressed as Z-scores or as three-dimensional BMD of the total body. The bone formation and bone resorption markers, as well as calcium and vitamin D, were all at the same levels in GH-deficient and healthy males, indicating identical bone turnover. The GH-deficient females, however, had significantly lower levels of bone markers compared to healthy females, indicating a reduced bone turnover. Oestrogen substitution of the GH-deficient females could explain this difference.

CONCLUSIONS

Compared to healthy control subjects GH-deficient males had, in contrast to GH-deficient females, significantly reduced BMD and BMC. This obvious gender difference seems to be caused by the oestrogen substitution given to the females, compensating for the lack of GH, an effect testosterone does not seem to possess.