A 10-year, prospective study of the metabolic effects of growth hormone replacement in adults

Genotypes associated with lipid metabolism contribute to differences in serum lipid profile of GH-deficient adults before and after GH replacement therapy

OBJECTIVE

GH deficiency (GHD) in adults is associated with an altered serum lipid profile that responds to GH replacement therapy (GHRT). This study evaluated the influence of polymorphisms in genes related to lipid metabolism on serum lipid profile before and after 1 year of GHRT in adults.

DESIGN AND METHODS

In 318 GHD patients, total cholesterol (TC) serum concentrations, LDL-C, HDL-C, and triglycerides (TG) were assessed. Using a candidate gene approach, 20 single nucleotide polymorphisms (SNPs) were genotyped. GH dose was individually titrated to obtain normal serum IGF1 concentrations.

RESULTS

At baseline, the minor alleles of cholesteryl ester transfer protein (CETP) gene SNPs rs708272 and rs1800775 were associated with higher serum TC and apolipoprotein E (APOE) gene SNP rs7412 with lower TC concentrations; CETP SNPs rs708272, rs1800775, and rs3764261 and apolipoprotein B (APOB) gene SNP rs693 with higher serum HDL-C; APOE SNP rs7412, peroxisome proliferator-activated receptor gamma (PPARG) gene SNP rs10865710 with lower LDL-C, and CETP SNP rs1800775 with higher LDL-C; and APOE/C1/C4/C2 cluster SNP rs35136575 with lower serum TG. After treatment, APOB SNP rs676210 GG genotype was associated with larger reductions in TC and LDL-C and PPARG SNP rs10865710 CC genotype with greater TC reduction. All associations remained significant when adjusted for age, sex, and BMI.

CONCLUSIONS

In GHD adults, multiple SNPs in genes related to lipid metabolism contributed to individual differences in baseline serum lipid profile. The GH treatment response in TC and LDL-C was influenced by polymorphisms in the APOB and PPARG genes.

Tumour recurrence and enlargement in patients with craniopharyngioma with and without GH replacement therapy during more than 10 years of follow-up

OBJECTIVE

Most patients who have been treated for craniopharyngioma (CP) are GH deficient (GHD). GH replacement therapy (GHRT) may stimulate tumour regrowth; and one of the concerns with long-term GHRT is the risk of tumour progression. Therefore, the objective was to study tumour progression in CP patients on long-term GHRT.

DESIGN

Case-control study.

PATIENTS AND METHODS

The criteria for inclusion of cases were: i) GHD caused by CP; ii) GHRT >3 years; and iii) regular imaging. This resulted in 56 patients (mean age at diagnosis 25±16 years) with a mean duration of GHRT of 13.6±5.0 years. As controls, 70 CP patients who had not received GHRT were sampled with regard to follow-up, gender, age at diagnosis and initial radiation therapy (RT).

RESULTS

The 10-year tumour progression-free survival rate (PFSR) for the entire population was 72%. There was an association (hazard ratio, P value) between PFSR and initial RT (0.13, 0.001) and residual tumour (3.2, 0.001). The 10-year PFSR was 88% for the GHRT group and 57% for the control group. Substitution with GHRT resulted in the following associations to PFSR: GHRT (0.57, 0.17), initial RT (0.16, <0.001), residual tumour (2.6, <0.01) and gender (0.57, 0.10). Adjusted for these factors, the 10-year PFSR was 85% for the GHRT group and 65% for the control group.

CONCLUSIONS

In patients with CP, the most important prognostic factors for the PFSR were initial RT and residual tumour after initial treatment. Long-term GHRT did not affect the PFSR in patients with CP.

Overall and cause-specific mortality in GH-deficient adults on GH replacement

OBJECTIVE

Hypopituitarism is associated with an increased mortality rate but the reasons underlying this have not been fully elucidated. The purpose of this study was to evaluate mortality and associated factors within a large GH-replaced population of hypopituitary patients.

DESIGN

In KIMS (Pfizer International Metabolic Database) 13,983 GH-deficient patients with 69,056 patient-years of follow-up were available.

METHODS

This study analysed standardised mortality ratios (SMRs) by Poisson regression. IGF1 SDS was used as an indicator of adequacy of GH replacement. Statistical significance was set to P<0.05.

RESULTS

All-cause mortality was 13% higher compared with normal population rates (SMR, 1.13; 95% confidence interval, 1.04-1.24). Significant associations were female gender, younger age at follow-up, underlying diagnosis of Cushing's disease, craniopharyngioma and aggressive tumour and presence of diabetes insipidus. After controlling for confounding factors, there were statistically significant negative associations between IGF1 SDS after 1, 2 and 3 years of GH replacement and SMR. For cause-specific mortality there was a negative association between 1-year IGF1 SDS and SMR for deaths from cardiovascular diseases (P=0.017) and malignancies (P=0.044).

CONCLUSIONS

GH-replaced patients with hypopituitarism demonstrated a modest increase in mortality rate; this appears lower than that previously published in GH-deficient patients. Factors associated with increased mortality included female gender, younger attained age, aetiology and lower IGF1 SDS during therapy. These data indicate that GH replacement in hypopituitary adults with GH deficiency may be considered a safe treatment.

High prevalence of chronic pituitary and target-organ hormone abnormalities after blast-related mild traumatic brain injury

Studies of traumatic brain injury from all causes have found evidence of chronic hypopituitarism, defined by deficient production of one or more pituitary hormones at least 1 year after injury, in 25–50% of cases. Most studies found the occurrence of posttraumatic hypopituitarism (PTHP) to be unrelated to injury severity. Growth hormone deficiency (GHD) and hypogonadism were reported most frequently. Hypopituitarism, and in particular adult GHD, is associated with symptoms that resemble those of PTSD, including fatigue, anxiety, depression, irritability, insomnia, sexual dysfunction, cognitive deficiencies, and decreased quality of life. However, the prevalence of PTHP after blast-related mild TBI (mTBI), an extremely common injury in modern military operations, has not been characterized. We measured concentrations of 12 pituitary and target-organ hormones in two groups of male US Veterans of combat in Iraq or Afghanistan. One group consisted of participants with blast-related mTBI whose last blast exposure was at least 1 year prior to the study. The other consisted of Veterans with similar military deployment histories but without blast exposure. Eleven of 26, or 42% of participants with blast concussions were found to have abnormal hormone levels in one or more pituitary axes, a prevalence similar to that found in other forms of TBI. Five members of the mTBI group were found with markedly low age-adjusted insulin-like growth factor-I (IGF-I) levels indicative of probable GHD, and three had testosterone and gonadotropin concentrations consistent with hypogonadism. If symptoms characteristic of both PTHP and PTSD can be linked to pituitary dysfunction, they may be amenable to treatment with hormone replacement. Routine screening for chronic hypopituitarism after blast concussion shows promise for appropriately directing diagnostic and therapeutic decisions that otherwise may remain unconsidered and for markedly facilitating recovery and rehabilitation.

Cachexia and sarcopenia: emerging syndromes of importance in dogs and cats

Cachexia is the loss of lean body mass (LBM) that affects a large proportion of dogs and cats with congestive heart failure (CHF), chronic kidney disease (CKD), cancer, and a variety of other chronic diseases. Sarcopenia, the loss of LBM that occurs with aging, is a related syndrome, although sarcopenia occurs in the absence of disease. As many of the diseases associated with muscle loss are more common in aging, cachexia and sarcopenia often are concurrent problems. Both cachexia and sarcopenia have important clinical implications because they are associated with increased morbidity and mortality. The pathophysiology of these 2 syndromes is complex and multifactorial, but recent studies have provided new information that has helped to clarify mechanisms and identify potential new targets for treatment. Newly identified mechanisms and pathways that mediate cachexia appear to act by increasing energy requirements, decreasing energy intake, impairing nutrient absorption, and causing metabolic alterations. Whereas cachexia and sarcopenia are important areas of research for drug development in people, they are only beginning to be recognized in veterinary medicine. Greater awareness and earlier diagnosis will help provide practical approaches to managing body weight and lean tissue in dogs and cats, as well as more directed targets for treatment.

Growth hormone deficiency in the transition period: body composition and gonad function

Recombinant GH therapy is normally administered to GH-deficient children in order to achieve a satisfactory height - the main target during childhood and adolescence. However, the role of GH does not end once final height has been reached, but continues during the so-called transition period. In this phase of life, the body undergoes several changes, both physical and psychological, that culminate in adulthood. During this period, GH has a part in numerous metabolic functions. These include the lipid profile, where it increases HDL and reduces LDL, with the global effect of cardiovascular protection. It also has important effects on body composition (improved muscle strength and lean body mass and reduced body fat), the achievement of proper peak bone density, and gonad maturation. Retesting during the transition period, involving measurement of IGF-I plus a provocative test (insulin tolerance test or GHRH + arginine test), is thus necessary to establish any persistent GH deficiency requiring additional replacement therapy. The close cooperation of the medical professionals involved in the patient's transition from a pediatric to an adult endocrinologist is essential. The aim of this review is to point out the main aspects of GH treatment on body composition, metabolic and gonad functions in the transition period.

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.

The benefit of long-term growth hormone (GH) replacement therapy in hypopituitary adults with GH deficiency: results of the German KIMS database

OBJECTIVE

To evaluate the treatment effects of long-term growth hormone (GH) replacement therapy in adults with GH deficiency (GHD) who were followed in KIMS Germany (Pfizer International Metabolic Database), a national surveillance study.

DESIGN

The analysis was performed using baseline and long-term data (range: 4-10 years) of 440 consecutively documented patients (216 women and 224 men) with GHD, aged 20 to 49 years, enrolled in KIMS Germany. Serum insulin-like growth factor I (IGF-I), fasting blood glucose, fasting serum total cholesterol and low-density lipoprotein cholesterol (LDL-C) as well as body mass index (BMI), waist circumference (WC) and hip circumference (HC) at baseline and at last visit were studied. Furthermore, QoL-AGHDA score was determined to assess quality-of-life (QoL).

RESULTS

The mean dose of GH over all years was 0.41 mg per day in women and 0.37 mg per day in men. IGF-I and IGF-I SDS levels (standard deviation score) increased significantly (p<0.001) during GH treatment. The QoL-AGHDA score decreased significantly (p<0.001), indicating long-lasting improvement in QoL. In total cholesterol, LDL-C and fasting blood glucose, no significant changes were found. Only six patients developed type 2 diabetes during follow-up. Females and males similarly increased significantly in BMI, WC and HC. During GH treatment, recurrences of pituitary or central nervous system tumours or further de novo neoplasia were reported in 6 or 11 patients, respectively. The number of the most frequently reported GH treatment-associated adverse events was low.

CONCLUSION

These observational data show long-term beneficial effects of GH replacement therapy on QoL and show no significant effects on total cholesterol, LDL-C or BMI, WC and HC. Additionally, our data indicate that GH replacement therapy in adults is well tolerated.

Positive association between plasma IGF1 and high-density lipoprotein cholesterol levels in adult nondiabetic subjects

AIMS

Low IGF1 levels have been associated with an increased cardiovascular risk. It is unknown however whether IGF1 mediates the atherosclerotic process by modulating high-density lipoprotein cholesterol (HDL-C) independently from confounders. To address this issue, we evaluated the association between IGF1 levels and HDL-C in nondiabetic subjects.

METHODS

A cross-sectional analysis was used in the context of the CAtanzaro MEtabolic RIsk factors Study. One thousand and four participants (aged 20-69 years), for whom HDL-C and IGF1 measurements were available, were eligible for the study.

RESULTS

After adjusting for gender and age, IGF1 levels were positively correlated with HDL-C, and negatively correlated with body mass index (BMI), waist circumference, blood pressure (BP), triglyceride, fasting insulin, and homeostasis model assessment (HOMA). In a logistic regression model adjusted for age and gender, IGF1 in the lowest tertile (<125 ng/ml) was associated with an increased risk of having low HDL-C (odds ratio (OR) 2.14, 95% confidence interval (CI) 1.4-3.0; P=4x10(-5)) compared with the highest tertile (>186 ng/ml). When BMI, waist circumference, total cholesterol, triglyceride, and HOMA index were added to the model, IGF1 remained significantly associated with increased risk of low HDL-C (OR 1.52, 95% CI 1.01-2.31; P=0.04). A stepwise multivariate regression analysis in a model including age, gender, BMI, total cholesterol, triglycerides, IGF1, HOMA, and BP showed that the variables significantly associated with HDL-C were gender (P<0.0001), triglycerides (P<0.0001), total cholesterol (P<0.0001), BMI (P<0.0001), IGF1 levels (P<0.0001), and HOMA (P=0.001), accounting for 32.6% of its variation.

CONCLUSIONS

These data provide evidence that IGF1 may be an independent modulator for HDL-C in nondiabetic individuals.

Discontinuation of growth hormone (GH) treatment during the transition phase is an important factor determining the phenotype of young adults with nonidiopathic childhood-onset GH deficiency

CONTEXT

Little is known about the impact of childhood-onset GH deficiency (GHD), in particular the duration of GH cessation during the transition phase, on adult phenotype.

OBJECTIVE

We investigated the association between the manifestations and management of GHD during childhood/adolescence and the clinical features of GHD in adulthood. DESIGN/SETTING/PATIENTS/INTERVENTION: Patients with reconfirmed childhood-onset GHD who resumed GH treatment as adults were identified from two sequential databases (n = 313). The cohort was followed up longitudinally from GH start in childhood to reinitiation of treatment in adulthood and 1 yr beyond. Analyses were performed in the total cohort and in subgroups of patients with idiopathic GHD (IGHD) and non-IGHD. The cohorts were stratified based on duration of GH cessation (short, < or = 2 yr; long, > 2 yr).

MAIN OUTCOME MEASURES

Regimen of pediatric GH administration, duration of GH interruption, IGF-I sd score, lipid concentrations, and quality of life were measured.

RESULTS

Mean duration of GH interruption was 4.4 yr. IGF-I sd score in adulthood was related to severity of childhood GHD. In non-IGHD patients, a longer duration of GH interruption was associated with a worse lipid profile (P < 0.0001). Non-IGHD patients who gained more height during childhood GH treatment reported better quality of life than those who gained less height (P < 0.05).

CONCLUSIONS

Pediatricians should tailor GH treatment, not only for its beneficial effect on growth but also for future health in adulthood. In adults with reconfirmed GHD, particularly those with non-IGHD, early recommencement of GH should be considered.

Models to predict changes in serum IGF1 and body composition in response to GH replacement therapy in GH-deficient adults

OBJECTIVE

Clinical response to GH therapy in GH-deficient (GHD) adults varies widely. Good predictors of treatment response are lacking. The aim of the study was to develop mathematical models to predict changes in serum IGF1 and body composition (BC) in response to GH therapy in GHD adults.

DESIGN AND METHODS

One hundred and sixty-seven GHD patients (103 men, median age 50 years) were studied before and after 12 months of GH treatment. GH dose was tailored according to serum IGF1 concentrations. Good responders (GR) and poor responders (PR) to GH therapy were defined as patients with a response >60th and <40th percentile respectively, for changes in serum IGF1 levels (adjusted for GH cumulative dose) and in BC (lean body mass (LBM) and body fat determined using dual-energy X-ray absorptiometry). A logistic regression model was used to predict the probability of being a GR or PR.

RESULTS

In the IGF1 prediction model, men (odds ratio (OR) 5.62: 95% confidence interval 2.59-12.18) and patients with higher insulin levels (OR 1.06: 1.00-1.12) were more likely to be GR. The accuracy of the prediction model was 70%. In the BC model, men (OR 10.72: 1.36-84.18) and GHD patients with lower LBM (OR 0.82: 0.73-0.92) and greater height (OR 1.23: 1.08-1.40) at baseline were more likely to be GR. The accuracy of the prediction model was 80%.

CONCLUSION

Accurate mathematical models to predict GH responsiveness in GHD adults were developed using gender, body height, baseline LBM, and serum insulin levels as the major clinical predictors.

Changes in endothelial dysfunction and associated cardiovascular disease morbidity markers in GH-IGF axis pathology

Arterial endothelial dysfunction is an early event in the pathogenesis of atherosclerosis and predisposes individuals to the deposition of unstable atherosclerotic plaques. It can also lead to increased arterial stiffness, which is an accepted cause of increased arterial pulse wave velocity (APWV). Endothelial dysfunction is reversed by recombinant human growth hormone (rhGH) therapy in patients with growth hormone (GH) deficiency (GHD), favorably influencing the risk for atherogenesis. Endogenous human growth hormone (hGH), secreted by the anterior pituitary, and levels of insulin-like growth factor-I (IGF-I), produced in response to hGH stimulation of the liver, peak during early adulthood, but decline throughout adulthood. It is suspected that low-grade inflammatory cardiovascular pathophysiologic markers such as homocysteine, nitric oxide, C-reactive protein (CRP), and fibrinogen and plasminogen activator inhibitor along with changes in lipid and glucose metabolism may all contribute to GHD-associated metabolic and cardiovascular complications. These effects are associated with increased APWV, but are attenuated by rhGH therapy in GHD. GH replacement increases IGF-I levels and reduces CRP and large-artery stiffness. Reviews of rhGH in the somatopause have not been overtly favorable. Whereas reviews of rhGH/rhIGF-I combinations in GH resistance are more positive than those for rhGH alone, their combined use in the somatopause is limited. Senescent individuals may benefit from such a combination.

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.

The value of IGF1 estimation in adults with GH deficiency

The GH/IGF1 system, like other endocrine systems, is dynamic and its activity changes with age and sexual maturation, and is influenced by body composition and other factors. A normal level of IGF1 does not exclude a diagnosis of GH deficiency (GHD) in adults, and the usefulness of IGF1 in the diagnosis of adult GHD has historically been confusing and contentious. The regulation of IGF1 secretion in adults is complex, and is not solely dependent on GH status with factors recognized to influence IGF1 status in patients with GHD including age, gender, exogenous estrogen therapy, prolactin status, and severity of GHD. The usefulness of IGF1 for monitoring treatment of GH disorders in adulthood is now widely accepted, especially as GH-dosing regimens for GHD have evolved from weight-based dosing (associated with overtreatment and side effects) to individualized dose-titration strategies, which maintain IGF1 within target limits. Sub-optimal replacement therapy may be associated with morbidity and mortality risk from a continuing state of functional GHD. Conversely, avoiding iatrogenic biochemical acromegaly is clearly important and other potential safety issues may be associated with a persistently high IGF1. Analysis and interpretation of IGF1 status therefore represent a useful diagnostic tool especially in the younger adult patients with severe GHD and an essential measurement for monitoring GH replacement in all adults with GHD. High-quality, method-specific reference ranges for IGF1 and a high degree of methodological consistency in the assay are essential for reliable comparison of results.

Growth hormone and sex steroid effects on serum glucose, insulin, and lipid concentrations in healthy older women and men

CONTEXT

With aging, GH, IGF-I, and sex steroid concentrations and glucose tolerance decrease, and body fat and serum lipids increase.

OBJECTIVE

The aim of the study was to assess GH and/or sex steroid administration effects on serum glucose, insulin, insulin sensitivity, and lipids in older individuals.

DESIGN

A double-masked, 2 x 2 factorial, placebo-controlled, double-dummy design was used for the study.

INTERVENTION

GH and/or sex steroid [transdermal estradiol plus oral medroxyprogesterone acetate in women (HRT); testosterone enanthate (T) in men] were administered for 6 months.

PARTICIPANTS

Healthy, community-dwelling women (n = 57) and men (n = 74) ages 65-88 yr (mean, 72 yr) participated in the study.

MAIN OUTCOME MEASURES

We measured serum glucose, insulin, and insulin sensitivity [quantitative insulin sensitivity check index (QUICKI) and insulin sensitivity index (ISI)] before and during an oral glucose tolerance test and lipid profiles.

RESULTS

In women, GH did not alter oral glucose tolerance test 120 min or 2-h area under the curve (AUC) glucose values, but it increased 120 min insulin and AUC insulin. There were no significant effects of HRT or GH+HRT. ISI and QUICKI decreased after GH. In men, GH increased 120 min and AUC glucose and insulin AUC. GH+T increased 120 min glucose and glucose and insulin AUCs. T alone did not affect glucose or insulin. ISI decreased after GH and GH+T, whereas QUICKI decreased after GH. GH in women and men and GH+T in men decreased QUICKI by 4 wk. In women, HRT decreased total cholesterol and low-density lipoprotein (LDL)-cholesterol, and GH decreased LDL-cholesterol. In men, total cholesterol decreased after T and GH+T. LDL-cholesterol decreased after GH and GH+T. GH increased serum triglycerides.

CONCLUSIONS

GH administration to healthy older individuals for 6 months increased insulin resistance with moderately beneficial effects on lipids.

[Congenital adrenal hyperplasia and growth hormone deficiency. Special care in transition to adulthood]

Children with chronically endocrine diseases should be treated as young adults by adult endocrinologists. To optimize the transfer from the pediatric to adult endocrinologist, the model of a common transition clinic has been developed. Within this setting it should be possible to exchange experiences, extend the knowledge and understanding of the disease with the other side, and to provide for the patient an optimal outpatient care. This model, however, has only been sporadically realized to date. To set an example for the problems of the transition into adult endocrinology, we used two different endocrine diseases, the classical congenital adrenal hyperplasia due to 21-hydroxylase deficiency, and the childhood-onset growth hormone deficiency. Specific problems for this transfer to adult care are the fixation of the patients to their pediatricians and the lack of comprehension in the need of a long term and continuous therapy. The consequence is a dramatic impairment in the quality of the therapy.

Age-related changes in body composition of bovine growth hormone transgenic mice

GH has a significant impact on body composition due to distinct anabolic and catabolic effects on lean and fat mass, respectively. Several studies have assessed body composition in mice expressing a GH transgene. Whereas all studies report enhanced growth of transgenic mice as compared with littermate controls, there are inconsistencies in terms of the relative proportion of lean mass to fat mass in these animals. The purpose of this study was to characterize the accumulation of adipose and lean mass with age and according to gender in a bovine (b) GH transgenic mouse line. Weight and body composition measurements were assessed in male and female bGH mice with corresponding littermate controls in the C57BL/6J genetic background. Body composition measurements began at 6 wk and continued through 1 yr of age. At the conclusion of the study, tissue weights were determined and triglyceride content was quantified in liver and kidney. Although body weights for bGH mice were significantly greater than their corresponding littermate controls at all time points, body composition measurements revealed an unexpected transition midway through analyses. That is, younger bGH mice had relatively more fat mass than nontransgenic littermates, whereas bGH mice became significantly leaner than controls by 4 months in males and 6 months in females. These results reveal the importance in timing and gender when conducting studies related to body composition or lean and fat tissue in GH transgenic mice or in other genetically manipulated mouse strains in which body composition may be impacted.

Changing patterns of the adult growth hormone deficiency diagnosis documented in a decade-long global surveillance database

BACKGROUND

GH therapy in adult patients with GH deficiency (GHD) was approved over 10 yr ago, and the indication has subsequently gained broad acceptance. The HypoCCS surveillance database is a suitable means to examine the evolution of diagnostic patterns since 1996.

METHODS

Baseline demographics, reported cause of GHD, and diagnostic tests were available from 5893 GH-treated patients. Trends for change over time in diagnosis, GH stimulation test data, and IGF-I measurements were analyzed at 2-yr intervals by linear regression models, with entry year as the predictive variable.

RESULTS

Over the decade, there was a decrease in patients enrolled with diagnoses of pituitary adenoma (50.2 to 38.6%; P < 0.001), craniopharyngioma (13.3 to 8.4%; P = 0.005) and pituitary hemorrhage (5.8 to 2.8%; P = 0.001); increases in idiopathic GHD (13.9 to 19.3%; P < 0.001), less common diagnoses (7.4 to 15.8%; P < 0.001), and undefined/unknown diagnoses (1.3 to 8.6%; P < 0.001) were observed. Use of arginine, clonidine, and L-dopa tests declined, whereas use of the GHRH-arginine test increased. Median values for peak GH from all tests except GHRH-arginine and for IGF-I SD scores increased significantly (P < 0.001). Over the decade (1996--2005), idiopathic GHD was reported for 16.7% of patients, and more than half of these had adult onset GHD. In the idiopathic adult onset group, 40.2% had isolated GHD; 18.3 and 4.4% had a stimulation test GH peak of at least 3.0 and 5.0 microg/liter, respectively.

CONCLUSIONS

Significant shifts in diagnostic patterns have occurred since approval of the adult GHD indication, with a trend to less severe forms of GHD.

Limited effects of growth hormone replacement in patients with GH deficiency during long-term cure of acromegaly

The aim of this study was to assess the effects of replacement with recombinant human growth hormone (rhGH) in patients with GH deficiency (GHD) after treatment of acromegaly. Intervention study. Sixteen patients (8 men, age 56 years), treated for acromegaly by surgery and radiotherapy, with an insufficient GH response to insulin-induced hypoglycaemia, were treated with 1 year of rhGH replacement. Study parameters were assessed at baseline and after 1 year of rhGH replacement. Study parameters were cardiac function, body composition, bone mineral density (BMD), fasting lipids, glucose, bone turnover markers, and Quality of Life (QoL). During rhGH replacement IGF-I concentrations increased from -0.4 +/- 0.7 to 1.0 +/- 1.5 SD (P = 0.001), with a mean daily dose of 0.2 +/- 0.1 mg in men and 0.3 +/- 0.2 mg in women. Nonetheless, rhGH replacement did not alter cardiac function, lipid and glucose concentrations, body composition or QoL. Bone turnover markers (PINP and beta crosslaps) levels increased (P = 0.005 and P = 0.021, respectively), paralleled by a small, but significant decrease in BMD of the hip. The beneficial effects of rhGH replacement in patients with GHD during cure from acromegaly are limited in this study.

Effects of growth hormone treatment on arginine to asymmetric dimethylarginine ratio and endothelial function in patients with growth hormone deficiency

Patients with growth hormone deficiency (GHD) are known to have reduced life expectancy due to increased cardiovascular and cerebrovascular events. An increase in asymmetric dimethylarginine (ADMA) levels previously found in GHD patients could promote premature atherosclerosis. The aim of this study was to determine whether 6-month growth hormone (GH) replacement therapy was able to decrease ADMA levels and ameliorate endothelial dysfunction. Thirty-one GHD patients were studied before and after 6 months of GH (4 microg/[kg d], daily) replacement therapy. Reduced pretreatment levels of serum insulin-like growth factor (IGF) 1 were normalized during GH treatment (88.2 +/- 62.5 to 191.7 +/- 80.3 ng/mL, P < .0001). After 6 months of GH replacement, plasma cyclic guanosine monophosphate levels significantly increased (2.14 +/- 0.52 to 3.54 +/- 1.2 ng/mL, P < .0001), serum ADMA levels were significantly decreased (0.65 +/- 0.1 vs 0.59 +/- 0.11 mumol/L, P < .05), and arganine (Arg) to ADMA ratio was significantly higher (155 +/- 53 vs 193 +/- 61, P < .01). No changes were observed for plasma nitric oxide end products (nitrite and nitrate) levels after GH treatment (21.9 +/- 14.9 vs 24.1 +/- 19.0 mumol/L, not significant). Basal forearm blood flow remained unchanged, whereas reactive hyperemia increased from 7.30 +/- 5.31 mL/100 mL forearm per minute before GH therapy to 13.18 +/- 7.30 mL/100 mL forearm per minute after 6 months of therapy (P < .001). There was a positive correlation between IGF-1 and cyclic guanosine monophosphate (r = 0.73, P < .0001), IGF-1 and reactive hyperemia (r = 0.63, P < .0001), and IGF-1 and Arg/ADMA ratio (r = 0.44, P < .01). Conversely, a negative correlation was found between IGF-1 and ADMA levels (r = -0.41, P < .02). At the end of the study period, fat-free mass, plasma glucose, and hemoglobin A(1c) levels significantly increased, even if they were still in the reference range, suggesting moderate alteration of glucose metabolism. In conclusion, in GHD patients, GH replacement contributes to decreased, to some extent, cardiovascular risk, reducing ADMA levels and improving Arg/ADMA ratio and endothelial dysfunction.

Adult-onset growth hormone deficiency: causes, complications and treatment options

PURPOSE OF REVIEW

Description of the progresses related to the complications and treatment of adult-onset growth hormone deficiency.

RECENT FINDINGS

Growth hormone deficiency in adults has gained attention as a clinical syndrome associated with increased morbidity and possibly mortality. Many studies have been conducted on the consequences of growth hormone deficiency and of its replacement, supporting its use in appropriate patients. Early studies were characterized by a high incidence of side effects due to a lack of pilot data to guide appropriate dosing. Given the wide variability in individual responsiveness to growth hormone therapy based on age, sex, and body composition, recent work has been dedicated to understanding which patients derive benefit from therapy, minimizing side effects, and ensuring cost-effectiveness.

SUMMARY

Long-term prospective trials have shown that growth hormone replacement therapy results in improvements in body composition, dyslipidemia, bone mineral density, and quality of life. The effects on endpoints such as cardiovascular morbidity and mortality and fractures are, however, not fully proven. Randomized trials that compare homogenous groups of growth hormone deficiency patients are still needed. Given the high cost of treatment, dynamic testing for growth hormone deficiency should only be performed in patients in whom there is high clinical suspicion, and therapy should be limited to those with biochemically proven growth hormone deficiency.

[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.

Influence of the d3-growth hormone (GH) receptor isoform on short-term and long-term treatment response to GH replacement in GH-deficient adults

OBJECTIVE

Recombinant human GH (rhGH) replacement in adults is aimed at improving signs and symptoms of the adult GH deficiency (GHD) syndrome. In children, a common polymorphism of the GH receptor (exon-3 deletion, d3GHR) increases the response to rhGH replacement. The aim of this study was to assess the effects of this polymorphism on the response to rhGH replacement in adults.

DESIGN

Prospective intervention with rhGH during 1 yr (n = 99) and in a subset during 5 yr (n = 53).

PATIENTS AND METHODS

The presence of the d3GHR variant was established in GHD patients and linked to short-term and long-term effects of rhGH replacement on IGF-I, lipid metabolism, anthropometric parameters, and bone mineral density.

RESULTS

Fifty-five patients had two wild-type alleles (56%), whereas 38 patients (38%) had one allele and six patients (6%) had two alleles coding the d3GHR isoform. During short-term rhGH replacement, the increase in IGF-I was higher in patients bearing at least one d3GHR allele, compared with those with two wild-type alleles (at an identical mean dose of rhGH). The decrease in total cholesterol and low-density lipoprotein cholesterol was lower in the group bearing at least one d3GHR allele, whereas the increase in high-density lipoprotein cholesterol was higher, compared with patients with the wild-type genotype. In contrast, these differential responses of GHR genotype could not be demonstrated during long-term rhGH replacement.

CONCLUSION

The d3GHR genotype contributes, at least for some parameters, to the interindividual differences in efficacy of short-term, but not long-term, rhGH replacement in adults with GHD.

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.

Pharmacodynamics of growth hormone abuse biomarkers and the influence of gender and testosterone: a randomized double-blind placebo-controlled study in young recreational athletes

CONTEXT

IGF axis proteins and collagen peptides are promising markers of GH abuse.

OBJECTIVE

Our objective was to investigate whether responses of serum IGF axis and collagen markers to GH differ between men and women, and are influenced by testosterone (T).

DESIGN

This was a randomized, double-blind, placebo-controlled study of 8-wk treatment followed by 6-wk washout.

SETTING

The study was performed at a clinical research facility.

PARTICIPANTS

A total of 96 recreationally trained healthy athletes (63 men, 33 women), aged 18-40 yr, were studied.

INTERVENTION

All subjects received GH (2 mg/d sc) or placebo for 8 wk; men also received T (250 mg/wk im) or placebo for 5 wk.

MAIN OUTCOME MEASURES

Serum IGF axis proteins (IGF-I, IGF binding protein-3, and acid labile subunit) and collagen peptides (N-terminal propeptide of type I procollagen, C-terminal telopeptide of type I collagen, and N-terminal propeptide of type III procollagen) were measured.

RESULTS

GH induced significant increases in IGF axis and collagen markers that were greater in men than women (P < 0.001). Of the IGF axis markers, IGF-I showed the greatest increase. The relative incremental responses of the collagen markers in general were greater than the IGF markers, especially for PIIINP. The collagen markers increased and decreased more slowly with most remaining elevated (P < 0.01) after 6 wk, in comparison to IGF markers, which returned to baseline within 1 wk. Addition of T to GH amplified the response of PIIINP by more than 1.5-fold but did not affect any other marker. T alone did not affect IGF axis markers but modestly increased collagen markers.

CONCLUSIONS

These markers of GH abuse are less responsive in women. The increases in collagen markers have a different time course to the IGF markers and extend the window of detection in both sexes. The response of PIIINP is increased by coadministration of T.