Effect of growth hormone replacement on BMD in adult-onset growth hormone deficiency

Effects of 18 Months of Growth Hormone Replacement Therapy on Bone Mineral Density in Patients with Adult Growth Hormone Deficiency: A Retrospective Study

OBJECTIVE

The effect of physiological dose growth hormone (GH) replacement therapy on bone mineral density (BMD) in adults with growth hormone deficiency (GHD) is not well defined. We aimed to investigate the effects of 18 months of treatment with recombinant human growth hormone (rhGH) at physiological doses on BMD, body composition (BC), and quality of life (QoL).

METHODS

Sixty-eight patients diagnosed with adult growth hormone deficiency (AGHD) in our hospital were included in this retrospective study. All patients received individualized rhGH replacement to maintain normal serum insulin-like growth factor-1 (IGF-1) levels. BMD and BC measurements were performed by dual energy X-ray absorptiometry (DXA). Excluding those with incomplete follow-up data, we analyzed BMD in 68 patients, as well as BC and QoL in 36 of them.

RESULTS

Compared with the baseline, lumbar spine BMD decreased by 0.008 g/cm² (P=0.006) and increased by 0.011 g/cm² (P=0.045) at month 18, and total hip BMD decreased by 0.005 g/cm² (P=0.008) and did not change significantly from the baseline at month 18. The changes in BMD did not differ by sex, and the increase in BMD was more pronounced in patients with low Z-scores at the baseline (lumbar spine: P=0.005 and total hip: P=0.018). The percentage change from the baseline in BMD was greater for the lumbar spine than for the total hip (P=0.003). Lean body mass (LBM) increased significantly (P=0.012), total body fat ratio (TBF%) decreased significantly (P=0.011), visceral adipose tissue (VAT) decreased significantly (P=0.016), and QoL improved significantly (P < 0.001).

CONCLUSIONS

Within 18 months of treatment, bone resorption manifested first, BMD decreased to a nadir at month 6, and then it increased. The increase in BMD was greater in the lumbar spine than in the hip, and the increase was more pronounced in patients with low BMD. Eighteen months of rhGH replacement therapy significantly improved lumbar spine BMD and improved BC and QoL.

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.

Combined Effects of Androgen and Growth Hormone on Osteoblast Marker Expression in Mouse C2C12 and MC3T3-E1 Cells Induced by Bone Morphogenetic Protein

Osteoblasts undergo differentiation in response to various factors, including growth factors and steroids. Bone mass is diminished in androgen- and/or growth hormone (GH)-deficient patients. However the functional relationship between androgen and GH, and their combined effects on bone metabolism, remains unclear. Here we investigated the mutual effects of androgen and GH on osteoblastic marker expression using mouse myoblastic C2C12 and osteoblast-like MC3T3-E1 cells. Combined treatment with dihydrotestosterone (DHT) and GH enhanced BMP-2-induced expression of Runx2, ALP, and osteocalcin mRNA, compared with the individual treatments in C2C12 cells. Co-treatment with DHT and GH activated Smad1/5/8 phosphorylation, Id-1 transcription, and ALP activity induced by BMP-2 in C2C12 cells but not in MC3T3-E1 cells. The insulin-like growth factor (IGF-I) mRNA level was amplified by GH and BMP-2 treatment and was restored by co-treatment with DHT in C2C12 cells. The mRNA level of the IGF-I receptor was not significantly altered by GH or DHT, while it was increased by IGF-I. In addition, IGF-I treatment increased collagen-1 mRNA expression, whereas blockage of endogenous IGF-I activity using an anti-IGF-I antibody failed to suppress the effect of GH and DHT on BMP-2-induced Runx2 expression in C2C12 cells, suggesting that endogenous IGF-I was not substantially involved in the underlying GH actions. On the other hand, androgen receptor and GH receptor mRNA expression was suppressed by BMP-2 in both cell lines, implying the existence of a feedback action. Collectively the results showed that the combined effects of androgen and GH facilitated BMP-2-induced osteoblast differentiation at an early stage by upregulating BMP receptor signaling.

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

BACKGROUND

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSION

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

Reviewing the safety of GH replacement therapy in adults

CONTEXT

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

OBJECTIVE

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

DESIGN

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

OUTCOME

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

RESULTS

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

CONCLUSION

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

Effects of up to 15 years of recombinant human GH (rhGH) replacement on bone metabolism in adults with growth hormone deficiency (GHD): the Leiden Cohort Study

BACKGROUND

Growth hormone deficiency (GHD) in adulthood may be associated with a decreased bone mineral density (BMD), a decreased bone mineral content (BMC) and an increased fracture risk. Recombinant human GH (rhGH) replacement induces a progressive increase in BMD for up to 5-7 years of treatment. Data on longer follow-up are, however, scarce.

METHODS

Two hundred and thirty-adult GHD patients (mean age 47·1 years, 52·6% female), of whom 88% patients had adult-onset (AO) GHD, receiving rhGH replacement for ≥5 years were included in the study. Most patients had multiple pituitary hormone deficiencies. Bone turnover markers, BMC and BMD and T-scores at the lumbar spine and femoral neck were evaluated at baseline, and after 5, 10 and 15 years of rhGH replacement. In addition, clinical fracture incidence was assessed.

RESULTS

Mean lumbar spine BMD, lumbar spine BMC and T-scores gradually increased during the first 10 years of rhGH replacement and remained stable thereafter. Largest effects of rhGH supplementation were found in men. In the small subset of patients using bisphosphonates, use of bisphosphonates did not impact additional beneficial effects in the long term. Low baseline BMD positively affected the change in BMD and BMC over time, but there was a negative effect of high GH dose at 1 year on the change in BMD and BMC over time. Clinical fracture incidence during long-term rhGH replacement was 20.1/1000 py.

CONCLUSIONS

Fifteen years of rhGH replacement in GHD adults resulted in a sustained increase in BMD values at the lumbar spine, particularly in men, and stabilization of BMD values at the femoral neck. Clinical fracture incidence was suggested not to be increased during long-term rhGH replacement.

Effects of testosterone and growth hormone on the structural and mechanical properties of bone by micro-MRI in the distal tibia of men with hypopituitarism

CONTEXT

Severe deficiencies of testosterone (T) and GH are associated with low bone mineral density (BMD) and increased fracture risk. Replacement of T in hypogonadal men improves several bone parameters. Replacement of GH in GH-deficient men improves BMD.

OBJECTIVE

Our objective was to determine whether T and GH treatment together improves the structural and mechanical parameters of bone more than T alone in men with hypopituitarism.

DESIGN AND SUBJECTS

This randomized, prospective, 2-year study included 32 men with severe deficiencies of T and GH due to panhypopituitarism.

INTERVENTION

Subjects were randomized to receive T alone (n = 15) or T and GH (n = 17) for 2 years.

MAIN OUTCOME MEASURES

We evaluated magnetic resonance microimaging-derived structural (bone volume fraction [BVF] and trabecular thickness) and mechanical (axial stiffness [AS], a measure of bone strength) properties of the distal tibia at baseline and after 1 and 2 years of treatment.

RESULTS

Treatment with T and GH did not affect BVF, thickness, or AS differently from T alone. T treatment in all subjects for 2 years increased trabecular BVF by 9.6% (P < .0001), trabecular thickness by 2.6% (P < .001), and trabecular AS by 9.8% (P < .001). In contrast, testosterone treatment in all subjects significantly increased cortical thickness by 2.4% (P < .01) but decreased cortical BVF by -4.7% (P < .01) and cortical AS by -6.9% (P < .01).

CONCLUSION

Combined T and GH treatment of men with hypopituitarism for 2 years did not improve the measured structural or mechanical parameters of the distal tibia more than T alone. However, testosterone significantly increased the structural and mechanical properties of trabecular bone but decreased most of these properties of cortical bone, illustrating the potential importance of assessing trabecular and cortical bone separately in future studies of the effect of testosterone on bone.

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.

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.

Differential effects of raloxifene and estrogen on body composition in growth hormone-replaced hypopituitary women

CONTEXT

GH deficiency causes reduction in muscle and bone mass and an increase in fat mass (FM), the changes reversed by GH replacement. The beneficial effects of GH on fat oxidation and protein anabolism are attenuated more markedly by raloxifene, a selective estrogen receptor modulator, compared with 17β-estradiol. Whether this translates to a long-term detrimental effect on body composition is unknown.

OBJECTIVE

Our objective was to compare the effects of 17β-estradiol and raloxifene on FM, lean body mass (LBM), and bone mineral density (BMD) during GH replacement.

DESIGN

This was an open-label randomized crossover study.

PATIENTS AND INTERVENTION

Sixteen hypopituitary women received GH (0.5 mg/d) replacement for 24 months. One group received 17β-estradiol (2 mg/d) for the first 6 months before crossover to raloxifene (60 mg/d) for the remaining 18 months; the other received the reversed sequence.

MAIN OUTCOME MEASURES

Serum IGF-I and IGF-binding protein-3 concentrations, and FM, LBM, lumbar spine and femoral neck BMD were analyzed at baseline and at 6, 12, and 24 months within and between subjects.

RESULTS

GH therapy significantly increased mean IGF-I during 17β-estradiol and raloxifene cotreatments equally, but elevated IGF-binding protein-3 to a greater extent during raloxifene cotreatment. GH cotreatment with 17β-estradiol increased LBM and lumbar spine and femoral neck BMD and reduced FM to a greater extent than with raloxifene.

CONCLUSIONS

In hypopituitary women, raloxifene at therapeutic doses significantly attenuated the beneficial effects of GH on body composition compared with 17β-estradiol. Raloxifene has no metabolic advantage over 17β-estradiol during GH replacement.

Neuroendocrine dysregulation and the growth hormone-IGF-1 axis in anorexia nervosa

Anorexia nervosa is a common psychiatric disorder characterized by extreme, self-induced starvation and is associated with a number of medical complications, including significant loss of bone mass. Disruption of the hypothalamic-pituitary axis has been demonstrated in anorexia nervosa and contributes to both loss of established bone mass in adults and failure to accrue normal bone mass in adolescents. Anorexia nervosa is associated with the development of a state of acquired growth hormone (GH) resistance, characterized by low IGF-1 and elevated GH levels, which may be mediated in part by FGF-21. Administration of supraphysiologic recombinant human GH does not result in an increase in markers of bone formation. However, treatment with recombinant human IGF-1, in combination with an oral contraceptive, increases markers of bone formation as well as bone mineral density, and may be a novel way to treat the bone loss associated with anorexia nervosa.

Effects of risedronate and low-dose transdermal testosterone on bone mineral density in women with anorexia nervosa: a randomized, placebo-controlled study

CONTEXT

Anorexia nervosa is complicated by severe bone loss and clinical fractures. Mechanisms underlying bone loss in adults with anorexia nervosa include increased bone resorption and decreased formation. Estrogen administration has not been shown to prevent bone loss in this population, and to date, there are no approved, effective therapies for this comorbidity.

OBJECTIVE

To determine whether antiresorptive therapy with a bisphosphonate alone or in combination with low-dose transdermal testosterone replacement would increase bone mineral density (BMD) in women with anorexia nervosa.

DESIGN AND SETTING

We conducted a12-month, randomized, placebo-controlled study at a clinical research center.

STUDY PARTICIPANTS

Participants included 77 ambulatory women with anorexia nervosa.

INTERVENTION

Subjects were randomized to risedronate 35 mg weekly, low-dose transdermal testosterone replacement therapy, combination therapy or double placebo.

MAIN OUTCOME MEASURES

BMD at the spine (primary endpoint), hip, and radius and body composition were measured by dual-energy x-ray absorptiometry.

RESULTS

Risedronate increased posteroanterior spine BMD 3%, lateral spine BMD 4%, and hip BMD 2% in women with anorexia nervosa compared with placebo in a 12-month clinical trial. Testosterone administration did not improve BMD but increased lean body mass. There were few side effects associated with either therapy.

CONCLUSIONS

Risedronate administration for 1 yr increased spinal BMD, the primary site of bone loss in women with anorexia nervosa. Low-dose testosterone did not change BMD but increased lean body mass.

Predictors of bone responsiveness to growth hormone (GH) replacement in adult GH-deficient patients

Growth hormone (GH) replacement in adulthood results in variable bone responses as a function of the gonadic hormonal milieu. We performed a retrospective analysis of a large cohort of adult males and females with confirmed GH deficiency (GHD) prior to treatment and during 3 years of replacement therapy. Potential confounders and effect modifiers were taken into account. Sixty-four adult patients with GHD (20 females and 44 males; mean age 34 years, range 18-64) were included in the analysis. GH replacement induced a different effect on bone in males compared to females. Bone mineral content increased in males and decreased in females at the lumbar spine, total femur, and femoral neck; bone mineral density showed a similar trend at the lumbar spine and femoral neck. There was no significant gender difference in bone area at any measured bone site. In both sexes we observed a similar trend for serum markers of bone remodeling. Sex predicted bone outcome on multivariate analysis, as did age, onset of GHD (childhood/adulthood), pretreatment bone mass, baseline body mass index (BMI), and BMI change during GH replacement. Serum IGF-I levels during treatment did not show any relationship with bone outcome at any measured site. This study confirms that bone responsiveness to GH replacement in adult GHD varies as a function of sex even after controlling for potential confounders and highlights the importance of other cofactors that may affect the interaction between GH replacement therapy and bone remodeling.

Effects of recombinant human growth hormone in anorexia nervosa: a randomized, placebo-controlled study

CONTEXT

Anorexia nervosa (AN), a state of chronic nutritional deprivation, is characterized by GH resistance with elevated GH levels and decreased levels of IGF-I. The effects of supraphysiological recombinant human GH (rhGH) on GH resistance in AN are not currently known.

OBJECTIVE

The aim was to investigate whether supraphysiological rhGH increases IGF-I levels in AN.

DESIGN AND SETTING

We conducted a randomized, placebo-controlled study in a Clinical Research Center.

PATIENTS

We studied 21 women with AN, 10 (mean age, 28 ± 2.1 yr) treated with rhGH and 11 (mean age, 29.2 ± 2.6 yr) treated with placebo.

INTERVENTIONS

rhGH (mean maximum daily dose, 1.4 ± 0.12 mg/d) or placebo was administered to patients for 12 wk.

MAIN OUTCOME MEASURES

IGF-I, N-terminal propeptide of type 1 procollagen, type I collagen C-telopeptide, glucose, and insulin levels were measured at wk 0, 1, 2, 3, 4, 8, and 12; C-terminal propeptide of type 1 procollagen, leptin, and free fatty acid levels were measured at wk 0 and 12. Body composition, including total fat and lean mass, was measured by dual-energy x-ray absorptiometry at wk 0 and 12.

RESULTS

IGF-I levels did not differ between the groups at baseline or after treatment (median after 12 wk-rhGH, 124 ng/ml, interquartile range, 94.5, 170.3; vs. placebo, 85.5 ng/ml, interquartile range, 62, 139; P = 0.3). Similarly, changes in glucose, insulin, free fatty acids, and bone markers did not differ between the groups. Total fat mass and percentage fat mass (rhGH, -2.5 ± 0.6%, vs. placebo, 2.2 ± 1.1%; P = 0.004) decreased significantly in the rhGH group compared to placebo despite comparable weight.

CONCLUSIONS

Supraphysiological rhGH administration decreases fat mass in AN without increasing IGF-I levels, supporting the role of GH as a mediator of lipolysis independent of IGF-I.

Approach to the patient with secondary osteoporosis

Secondary osteoporosis is characterized by low bone mass with microarchitectural alterations in bone leading to fragility fractures in the presence of an underlying disease or medication. Scenarios that are highly suspicious for secondary osteoporosis include fragility fractures in younger men or premenopausal women, very low bone mineral density (BMD) values, and fractures despite anti-osteoporotic therapy. An open-minded approach with a detailed history and physical examination combined with first-line laboratory tests are aimed at identifying clinical risk factors for fractures, osteoporosis-inducing drugs, and underlying endocrine, gastrointestinal, hematologic, or rheumatic diseases, which then need to be confirmed by specific and/or more invasive tests. BMD should be assessed with bone densitometry at the hip and spine. Lateral X-rays of the thoracic and lumbar spine should be performed to identify or exclude prevalent vertebral fractures which may be clinically silent. Management of secondary osteoporosis includes treatment of the underlying disease, modification of medications known to affect the skeleton, and specific anti-osteoporotic therapy. Calcium and vitamin D supplementation should be initiated with doses that result in normocalcemia and serum 25-hydroxyvitamin D concentrations of at least 30 ng/ml. Oral and i.v. bisphosphonates are effective and safe drugs for most forms of secondary osteoporosis. Severe osteoporosis may require the use of teriparatide.

Modulatory effect of raloxifene and estrogen on the metabolic action of growth hormone in hypopituitary women

CONTEXT

The metabolic action of GH is attenuated by estrogens administered via the oral route. Selective estrogen receptor modulators lower IGF-I to a lesser degree than 17beta-estradiol in GH-deficient women, and their effect on fat and protein metabolism is unknown.

OBJECTIVE

The aim of the study was to compare the modulatory effects of 17beta-estradiol and raloxifene, a selective estrogen receptor modulator, on the metabolic action of GH.

DESIGN

We conducted an open-label, two-group, randomized, two-period crossover study.

PATIENTS AND INTERVENTION

Ten hypopituitary women received GH therapy alone (0.5 mg/d) and GH plus 17beta-estradiol (E(2); 2 mg/d). Eleven hypopituitary women received GH therapy alone and GH plus raloxifene (R; 60 mg/d). The treatment duration was 1 month, with a 4-wk washout period.

MAIN OUTCOME MEASURES

IGF-I, IGFBP-3, resting energy expenditure, and fat oxidation were quantified by indirect calorimetry. We measured whole body leucine turnover from which leucine rate of appearance and leucine incorporation into protein were estimated.

RESULTS

GH significantly stimulated all outcome measures. During GH treatment, addition of R significantly reduced mean IGF-I but not IGFBP-3, whereas E(2) reduced both IGF-I and IGFBP-3 levels. Cotreatment with R but not E(2) significantly attenuated the stimulatory effects of GH on fat oxidation. There was a strong trend (P = 0.08) toward a greater reduction in leucine incorporation into protein after R compared to E(2) cotreatment.

CONCLUSIONS

The modulatory effects of E(2) and R at therapeutic doses on GH action are different. R during GH therapy exerts a greater inhibitory effect on lipid oxidation and protein anabolism compared to E(2).

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.

Pereira F, Oliveira CRP, Pereira RMC, Farias CT, Vicente TAR, Salvatori R. Consequences of lifetime isolated growth hormone (GH) deficiency and effects of short-term GH treatment on bone in adults with a mutation in the GHRH-receptor gene

OBJECTIVE

Growth hormone (GH) influences bone mass maintenance. However, the consequences of lifetime isolated GH deficiency (IGHD) on bone are not well established. We assessed the bone status and the effect of 6 months of GH replacement in GH-naive adults with IGHD due to a homozygous mutation of the GH-releasing hormone (GHRH)-receptor gene (GHRHR).

PATIENTS AND METHODS

We studied 20 individuals (10 men) with IGHD at baseline, after 6 months of depot GH treatment, and 6 and 12 months after discontinuation of GH. Quantitative ultrasound (QUS) of the heel was performed and serum osteocalcin (OC) and C-terminal cross-linking telopeptide of type I collagen (ICTP) were measured. QUS was also performed at baseline and 12 months later in a group of 20 normal control individuals (CO), who did not receive GH treatment.

RESULTS

At baseline, the IGHD group had a lower T-score on QUS than CO (-1.15 +/- 0.9 vs.-0.07 +/- 0.9, P < 0.001). GH treatment improved this parameter, with improvement persisting for 12 months post-treatment (T-score for IGHD = -0.59 +/- 0.9, P < 0.05). GH also caused an increase in serum OC (baseline vs. pGH, P < 0.001) and ICTP (baseline vs. pGH, P < 0.01). The increase in OC was more marked during treatment and its reduction was slower after GH discontinuation than in ICTP.

CONCLUSIONS

These data suggest that lifetime severe IGHD is associated with significant reduction in QUS parameters, which are partially reversed by short-term depot GH treatment. The treatment induces a biochemical pattern of bone anabolism that persists for at least 6 months after treatment discontinuation.

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.

Bone demineralization in adult thalassaemic patients: contribution of GH and IGF-I at different skeletal sites

BACKGROUND AND OBJECTIVE

GH and IGF-I exert an important role in the control of bone formation, as shown by decreased bone mineral density and increased fracture risk in adult hypopituitary patients untreated for GH deficiency (GHD). Different degrees of bone demineralization are frequently reported in patients affected by beta-thalassaemia. Considering the high prevalence of GHD recently observed by our group among adult thalassaemic patients, we elected to study the possible role of GH-IGF-I abnormalities in the pathogenesis of the osteopenia/osteoporosis of this disease.

DESIGN

Sixty-four adult thalassaemic patients (49 with thalassaemia major and 15 with thalassaemia intermedia, 23 men and 41 women, aged 31.4 +/- 6.8 years) were studied.

METHODS

Bone mineral density was assessed by dual energy X-ray absorptiometry at lumbar spine in 62 patients and at proximal femur in 58. All patients underwent GHRH (1 microg/kg as an i.v. bolus) plus arginine (0.5 g/kg as a 30-min i.v. infusion) testing. Severe GHD was defined by GH peaks < 9 microg/l, whereas partial GHD was defined by GH peaks ranging from 9 to 16.5 microg/l. Blood samples for IGF-I measurement were collected.

RESULTS

Lumbar osteoporosis and osteopenia were demonstrated in 46/62 (74.1%) and 14/62 (22.5%) patients, respectively. Femoral osteoporosis and osteopenia were documented in 22/58 (37.9%) and 32/58 (55.1%) patients, respectively. Severe GHD was demonstrated in 16/64 patients (25%), while 11 additional patients (17.1%) displayed partial GHD. IGF-I standard deviation score (SDS) was low, that is, below -1.88, in the majority (54.6%) of patients. Lumbar T-score values were not correlated with either GH peaks or IGF-I SDS values. Femoral T-score values were positively correlated with GH peaks (r = 0.38, P < 0.005) and IGF-I SDS values (r = 0.39, P < 0.005). Multiple regression analysis pointed to both GH peak and IGF-I SDS as predictors of femoral T-score. Furthermore, mean femoral T-score was significantly lower in patients with severe GHD than in those with normal GH secretion (-2.94 +/- 0.25 vs.-2.15 +/- 0.12, P < 0.01).

CONCLUSION

This study, while confirming the high prevalence of both osteopenia/osteoporosis and somatotropin-somatomedin deficiency in adult thalassaemic patients, indicates that defective GH secretion and diminished serum IGF-I levels may contribute to femoral demineralization in these patients. Further studies are worth carrying out to evaluate the efficacy of biosynthetic GH administration on bone abnormalities of GH-deficient thalassaemic adults.

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.

[Long time consequences of the growth hormone deficiency]

This article describes the long time consequences of the isolated and lifetime growth hormone (GH) deficiency using a single model of GH releasing hormone resistance (GHRH) due to a homozygous mutation in the GHRH receptor gene, in a hundred of subjects. These consequences include severe short stature with final height between -9.6 and -5.2 standard deviations below of the mean, with proportional reductions of the bone dimensions; reduction of the anterior pituitary corrected to cranial volume and the thyroid, the uterus, the spleen and left ventricular mass volume, all corrected to body surface, in contrast of pancreas and liver size, bigger than in controls, when equally corrected. Body composition features included marked reduction in the amount of fat free mass (kg) and increase of fat mass percentage, with predominant abdominal deposit. In the metabolic aspects, we find increase in the total cholesterol and LDL cholesterol; reduction of the insulin and the insulin resistance assessed by Homeostasis model assessment; increase of ultra sensitive C reactive protein and systolic body pressure in adults, although without evidences of premature atherosclerosis. Other findings include smaller bone resistance, although above of the threshold of fractures, delayed puberty, normal fertility, small parity, anticipated climacteric and normal quality of life.