Growth Hormone and Bone Health

Fracture risk in adult patients treated with growth hormone replacement therapy for growth hormone deficiency: a prospective observational cohort study

BACKGROUND

To our knowledge, no controlled studies of the effects of long-term growth hormone replacement on fracture risk in adult patients with growth hormone deficiency exist. We assessed the effect of growth hormone treatment on fracture risk in patients with growth hormone deficiency from the international Hypopituitary Control and Complications Study (HypoCCS) surveillance database.

METHODS

In this prospective cohort study, patients with growth hormone deficiency were analysed from the HypoCCS database of adults with hypopituitarism from the USA, Canada, Japan, and 14 European countries. Patients were eligible if they were aged 18 years or older and had an established diagnosis of growth hormone deficiency, either alone or with multiple pituitary hormone deficiencies, as identified by clinical history and biochemical testing. Patients were assessed over a mean follow-up period of 4·6 years (SD 3·8). The effect of growth hormone treatment on fracture risk was assessed by Cox proportional hazard modelling with adjustment for several confounders.

FINDINGS

Between Jan 3, 1996, and Dec 15, 2012, we enrolled 10,673 patients to this study. Of the enrolled patients, 1032 patients were excluded from assessment because of incomplete data, leaving 9641 in the analysis cohort. Of these patients, 8374 of received growth hormone and 1267 did not. Annual fracture incidence rate was lower in patients who received growth hormone than in those who did not (fracture incidence rate 1·19% vs 1·91%, hazard ratio [HR] 0·69, 95% CI 0·54-0·88). However, no difference in fracture risk was observed between patients who did and did not receive growth hormone treatment in the subgroup of patients with pre-existing osteoporosis (n=826; 0·97, 0·48-1·95).

INTERPRETATION

Our results suggest that growth hormone replacement therapy could be protective against fracture for adult patients with growth hormone deficiency without previously reported osteoporosis. Starting growth hormone therapy before the onset of osteoporosis might be optimum for bone health of adult patients with growth hormone deficiency.

FUNDING

Eli Lilly and Co.

Vitamin B₁₂-dependent taurine synthesis regulates growth and bone mass

Both maternal and offspring-derived factors contribute to lifelong growth and bone mass accrual, although the specific role of maternal deficiencies in the growth and bone mass of offspring is poorly understood. In the present study, we have shown that vitamin B12 (B12) deficiency in a murine genetic model results in severe postweaning growth retardation and osteoporosis, and the severity and time of onset of this phenotype in the offspring depends on the maternal genotype. Using integrated physiological and metabolomic analysis, we determined that B12 deficiency in the offspring decreases liver taurine production and associates with abrogation of a growth hormone/insulin-like growth factor 1 (GH/IGF1) axis. Taurine increased GH-dependent IGF1 synthesis in the liver, which subsequently enhanced osteoblast function, and in B12-deficient offspring, oral administration of taurine rescued their growth retardation and osteoporosis phenotypes. These results identify B12 as an essential vitamin that positively regulates postweaning growth and bone formation through taurine synthesis and suggests potential therapies to increase bone mass.

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.

Growth hormone therapy and craniofacial bones: a comprehensive review

Growth hormone (GH) has significant effects on linear bone growth, bone mass and bone metabolism. The primary role of GH supplementation in children with GH deficiency, those born small for gestational age or with other types of disorders in somatic development is to increase linear growth. However, GH therapy seems to elicit varying responses in the craniofacial region. Whereas the effects of GH administration on somatic development are well documented, comparatively little is known of its effects on the craniofacial region. The purpose of this review was to search the literature and compile results from both animal and human studies related to the impact of GH on craniofacial growth.

Human conditions of insulin-like growth factor-I (IGF-I) deficiency

Insulin-like growth factor I (IGF-I) is a polypeptide hormone produced mainly by the liver in response to the endocrine GH stimulus, but it is also secreted by multiple tissues for autocrine/paracrine purposes. IGF-I is partly responsible for systemic GH activities although it possesses a wide number of own properties (anabolic, antioxidant, anti-inflammatory and cytoprotective actions). IGF-I is a closely regulated hormone. Consequently, its logical therapeutical applications seems to be limited to restore physiological circulating levels in order to recover the clinical consequences of IGF-I deficiency, conditions where, despite continuous discrepancies, IGF-I treatment has never been related to oncogenesis. Currently the best characterized conditions of IGF-I deficiency are Laron Syndrome, in children; liver cirrhosis, in adults; aging including age-related-cardiovascular and neurological diseases; and more recently, intrauterine growth restriction. The aim of this review is to summarize the increasing list of roles of IGF-I, both in physiological and pathological conditions, underlying that its potential therapeutical options seem to be limited to those proven states of local or systemic IGF-I deficiency as a replacement treatment, rather than increasing its level upper the normal range.

Growth hormone effects on cortical bone dimensions in young adults with childhood-onset growth hormone deficiency

Growth hormone (GH) treatment in young adults with childhood-onset GH deficiency has beneficial effects on bone mass. The present study shows that cortical bone dimensions also benefit from GH treatment, with endosteal expansion and increased cortical thickness leading to improved bone strength.

INTRODUCTION

In young adults with childhood-onset growth hormone deficiency (CO GHD), GH treatment after final height is reached has been shown to have beneficial effects on spine and hip bone mineral density. The objective of the study was to evaluate the influence of GH on cortical bone dimensions.

METHODS

Patients (n = 160; mean age, 21.2 years; 63% males) with CO GHD were randomised 2:1 to GH or no treatment for 24 months. Cortical bone dimensions were evaluated by digital x-ray radiogrammetry of the metacarpal bones every 6 months.

RESULTS

After 24 months, cortical thickness was increased compared with the controls (6.43%, CI 3.34 to 9.61%; p = 0.0001) and metacarpal index (MCI) (6.14%, CI 3.95 to 8.38%; p < 0.0001), while the endosteal diameter decreased (-4.64%, CI -7.15 to -2.05; p < 0.001). Total bone width did not change significantly (0.68%, CI -1.17 to 2.57%; not significant (NS)). A gender effect was seen on bone width (p < 0.0001), endosteal diameter (p < 0.01) and cortical thickness (p < 0.01), but not with MCI (NS).

CONCLUSIONS

Cortical bone reacts promptly to reinstitution of GH beyond the attainment of final height by increasing the cortical thickness through endosteal bone growth. This leads to a higher peak bone mass and may reduce the risk of cortical bone fragility later in life.

Body composition and quality of life in adults treated with GH therapy: a systematic review and meta-analysis

OBJECTIVE

To summarise the evidence about the efficacy and safety of using GH in adults with GH deficiency focusing on quality of life and body composition.

DATA SOURCES

We searched MEDLINE, EMBASE, Cochrane CENTRAL, Web of Science and Scopus through April 2011. We also reviewed reference lists and contacted experts to identify candidate studies.

STUDY SELECTION

Reviewers, working independently and in duplicate, selected randomised controlled trials (RCTs) that compared GH to placebo.

DATA SYNTHESIS

We pooled the relative risk (RR) and weighted mean difference (WMD) by the random effects model and assessed heterogeneity using the I(2) statistic.

RESULTS

Fifty-four RCTs were included enrolling over 3400 patients. The quality of the included trials was fair. GH use was associated with statistically significant reduction in weight (WMD, 95% confidence interval (95% CI): -2.31 kg, -2.66 and -1.96) and body fat content (WMD, 95% CI: -2.56 kg, -2.97 and -2.16); increase in lean body mass (WMD, 95% CI: 1.38, 1.10 and 1.65), the risk of oedema (RR, 95% CI: 6.07, 4.34 and 8.48) and joint stiffness (RR, 95% CI: 4.17, 1.4 and 12.38); without significant changes in body mass index, bone mineral density or other adverse effects. Quality of life measures improved in 11 of the 16 trials although meta-analysis was not feasible.

RESULTS

GH therapy in adults with confirmed GH deficiency reduces weight and body fat, increases lean body mass and increases oedema and joint stiffness. Most trials demonstrated improvement in quality of life measures.

The effects of physical activity on the epiphyseal growth plates: a review of the literature on normal physiology and clinical implications

Background

Children need physical activity and generally do this through the aspect of play. Active play in the form of organized sports can appear to be a concern for parents. Clinicians should have a general physiological background on the effects of exercise on developing epiphyseal growth plates of bone. The purpose of this review is to present an overview of the effects of physical activity on the developing epiphyseal growth plates of children.

Methods

A National Library of Medicine (Pubmed) search was initiated using the keywords and combinations of keywords "growth plate", "epiphyseal plate", "child", "exercise", and "physical activity."

Discussion

Bone is a dynamic tissue with a balance of osteoblast and osteoclast formation. The normal functioning of the epiphyseal growth plate is an important clinical aspect. Much of the physiology of the epiphyseal growth plate in response to exercise includes the important mechanical component. Growth hormone, insulin-like growth factor I, glucocorticoid, thyroid hormone, estrogen, androgen, vitamin D, and leptin are seen as key physiological factors. While there is a need for children to participate in physical activity, clinical consideration needs to be given to how the epiphyseal growth plate functions.

Conclusions

Mechanical loading of the bone is important for epiphyseal plate physiology. Exercise has a healthy function on the normal growth of this important biomechanical feature. Clinically, over-exertion in the form of increased load bearing on the epiphyseal growth plate creates an ideal injury. There is a paucity of research on inactivity on the epiphyseal growth plate resulting in stress deprivation. Further research should take into consideration what lack of exercise and lessened mechanical load bearing has on the function of the epiphyseal growth plate.

Keywords

Child; Physical activity; Epiphyseal growth plates; Bone; Exercise; Mechanical loading

Effects of growth hormone on bone modeling and remodeling in hypophysectomized young female rats: a bone histomorphometric study

Growth hormone (GH) deficiency causes decreased bone mineral density and osteoporosis, predisposing to fractures. We investigated the mechanism of action of GH on bone modeling and remodeling in hypophysectomized (HX) female rats. Thirty female Sprague-Dawley rats at age 2 months were divided into three groups with 10 rats each: control (CON) group, HX group, and HX + GH (3 mg/kg daily s.c.) group, for a 4-week study. Hypophysectomy resulted in cessation of bone growth and decrease in cancellous bone mass. Periosteal bone formation decreased and bone turnover rate of endocortical and trabecular surfaces increased as compared to the CON group. GH administration for 4 weeks restored weight gain and bone growth and mitigated decrease in bone density after hypophysectomy. However, trabecular bone mass in the proximal tibial metaphysis remained lower in group HX + GH than in group CON. Dynamic histomorphometric analysis showed that bone modeling of periosteal bone formation and growth plate elongation was significantly higher in group HX + GH than in group HX. New bone formed beneath the growth plate was predominately woven bone in group CON and group HX + GH. Bone remodeling and modeling-remodeling mixed modes in the endocortical and PTM sites were enhanced by GH administration; both bone formation and resorption activities were significantly higher than in group HX. In conclusion, GH administration to HX rats reactivated modeling activities in modeling predominant sites and increased new bone formation. GH administration also increases remodeling activities in remodeling predominant sites, giving limited net gain in the bone mass.

GH and IGF1 levels are positively associated with musculotendinous collagen expression: experiments in acromegalic and GH deficiency patients

OBJECTIVE

Disproportionate growth of musculoskeletal tissue is a major cause of morbidity in both acromegalic (ACRO) and GH-deficient (GHD) patients. GH/IGF1 is likely to play an important role in the regulation of tendon and muscle collagen. We hypothesized that the local production of collagen is associated with the level of GH/IGF1.

DESIGN AND METHODS

As primary outcomes, collagen mRNA expression and collagen protein fractional synthesis rate (FSR) were determined locally in skeletal muscle and tendon in nine ACRO and nine GHD patients. Moreover, muscle myofibrillar protein synthesis and tendon collagen morphology were determined.

RESULTS AND CONCLUSIONS

Muscle collagen I and III mRNA expression was higher in ACRO patients versus GHD patients (P<0.05), whereas collagen protein FSR did not differ significantly between ACRO and GHD patients in muscle (P=0.21) and tendon (P=0.15). IGF1Ea and IGF1Ec mRNA expression in muscle was higher in ACRO patients versus GHD patients (P<0.01). Muscle IGF1Ea mRNA expression correlated positively with collagen I mRNA expression (P<0.01). Tendon collagen fibrillar area tended to be higher in GHD patients relative to ACRO patients (P=0.07). Thus, we observed a higher expression for collagen and IGF1 mRNA in local musculotendinous tissue in ACRO patients relative to GHD patients. Moreover, there was a tendency towards a higher collagen protein FSR and a smaller collagen fibril diameter in ACRO patients relative to GHD patients. The results indicate a collagen-stimulating role of local IGF1 in human connective tissue and add to the understanding of musculoskeletal pathology in patients with either high or low GH/IGF1 axis activity.

Bone quantitative ultrasound in congenital and acquired childhood multiple pituitary failure

The aim of the present study is to investigate bone status by phalangeal quantitative ultrasound (QUS) in a cohort of hypopituitaric pediatric subjects, and to relate measurement outcome to their clinical, laboratory, and therapeutical features. Forty-three hypopituitaric children were submitted to bone measurement by QUS with DBM sonic bone profiler 1200 (IGEA, Carpi, Modena, Italy). This method measures bone transmission time (BTT) and amplitude-dependent speed of sound (AD-SoS) of an ultrasound beam crossing the first four phalanges of the hand and provides respective standard deviation scores (SDS). These two parameters provide information on bone mineral density and structure. Clinical, laboratory and therapeutical features were considered to look for correlations. Overall BTT and AD-SoS SDS were significantly reduced (-0.87 +/- 1.52, p = 0.001, and -0.97 +/- 1.56, p = 0.001) as well as respective height- or bone age-corrected SDS. Bone condition proved significantly worse in subjects with higher number of hormonal deficiencies (p = 0.001 for both parameters) and in those with acquired hypopituitarism (p = 0.020 for BTT and p = 0.010 for AD-SoS) than in those with congenital forms. In participants under growth hormone (GH) treatment, regression analysis revealed that QUS measurement outcome was significantly associated with age at GH therapy start (p = 0.001), time interval before therapy initiation (p = 0.011), treatment duration (p = 0.007) and administered dosage (p = 0.036). Our data show that childhood hypopituitarism is associated with bone morbidity, detectable at QUS measurement independently of potential confounders as stature and bone age. Skeletal impairment is related to acquired hypopituitarism, number of hormonal deficiencies and duration of disease before replacement therapies, whereas GH treatment duration and doses are associated with a better skeletal condition. Phalangeal QUS measurements of BTT and AD-SoS promise as a reliable method for obtaining quantitative measurements of bone disease in individuals with hypopituitarism but more studies are needed for verification.

Role of the GH/IGF-1 axis in lifespan and healthspan: lessons from animal models

Animal models are fundamentally important in our quest to understand the genetic, epigenetic, and environmental factors that contribute to human aging. In comparison to humans, relatively short-lived mammals are useful models as they allow for rapid assessment of both genetic manipulation and environmental intervention as related to longevity. These models also allow for the study of clinically relevant pathologies as a function of aging. Data associated with more distant species offers additional insight and critical consideration of the basic physiological processes and molecular mechanisms that influence lifespan. Consistently, two interventions, caloric restriction and repression of the growth hormone (GH)/insulin-like growth factor-1/insulin axis, have been shown to increase lifespan in both invertebrates and vertebrate animal model systems. Caloric restriction (CR) is a nutrition intervention that robustly extends lifespan whether it is started early or later in life. Likewise, genes involved in the GH/IGF-1 signaling pathways can lengthen lifespan in vertebrates and invertebrates, implying evolutionary conservation of the molecular mechanisms. Specifically, insulin and insulin-like growth factor-1 (IGF-1)-like signaling and its downstream intracellular signaling molecules have been shown to be associated with lifespan in fruit flies and nematodes. More recently, mammalian models with reduced growth hormone (GH) and/or IGF-1 signaling have also been shown to have extended lifespans as compared to control siblings. Importantly, this research has also shown that these genetic alterations can keep the animals healthy and disease-free for longer periods and can alleviate specific age-related pathologies similar to what is observed for CR individuals. Thus, these mutations may not only extend lifespan but may also improve healthspan, the general health and quality of life of an organism as it ages. In this review, we will provide an overview of how the manipulation of the GH/IGF axis influences lifespan, highlight the invertebrate and vertebrate animal models with altered lifespan due to modifications to the GH/IGF-1 signaling cascade or homologous pathways, and discuss the basic phenotypic characteristics and healthspan of these models.

Wnt and steroid pathways control glutamate signalling by regulating glutamine synthetase activity in osteoblastic cells

Glutamate signalling has recently been found functional also outside the central nervous system, especially in bone. Glutamate is converted to glutamine by glutamine synthetase (GS), which is therefore able to regulate intracellular concentrations of glutamate. We previously characterized the induction of GS expression by glucocorticoids (GCs) in human osteoblast-like cells. Besides this observation, the mechanisms controlling GS in bone are unknown. Therefore, the aim of our present study was to investigate further the regulation of GS in osteoblastic cells. We observed that vitamin D inhibited basal and, even more efficiently, GC-stimulated GS activity by affecting both the mRNA and protein levels of the enzyme in human MG-63 osteoblast-like cells. In osteoblasts derived from rat bone marrow stem cells (rMSCs), GS activity was induced accordingly by the osteogenic culture conditions including GCs. Also in these primary cells, vitamin D clearly inhibited GS activity. In addition, the canonical Wnt signalling pathway was characterized as a negative regulator of GS activity. All these changes in GS activity were reflected on the intracellular glutamate concentration. Our results provide novel evidence that GS activity and expression are regulated by several different signalling pathways in osteoblastic cells. Therefore, GS is a strategic enzyme in controlling glutamate concentration in bone environment: GCs decreased the amount of this signalling molecule while vitamin D and Wnt signalling pathway increased it. Interestingly, GS activity and expression declined rapidly when the rMSC derived osteoblasts began to mineralize. Due to its downregulation during osteoblast mineralization, GS could be held as a marker for osteoblast development. Further supporting this, GS activity was stimulated and intracellular glutamate concentration maintained by the N-methyl-d-aspartate (NMDA) type glutamate receptor antagonist MK801, which inhibited osteogenic differentiation of the rMSCs. GS, a novel target for both steroidal and Wnt pathways in bone, might be a central player in the regulation of osteoblastogenesis and/or intercellular signal transmission. Therefore, the proper understanding of the interplay of these three signalling cascades, i.e., steroidal, Wnt, and glutamate signalling, gives vital information on how bone cells communicate together aiming to keep bone healthy.

Evaluation of catch-up growth from orthodontic treatment and supplemental growth hormone therapy by using Z-scores

Pituitary dwarfism causes short stature due to partial or complete inhibition of growth hormone (GH) secretion. Supplemental therapy with human GH (rhGH) accelerates the statural growth of patients, but there is limited information about its effects on craniofacial growth. This study describes the orthodontic treatment of 2 patients (a boy and a girl) diagnosed with pituitary dwarfism and treated with rhGH therapy. Growing children have different growth velocities depending on age and sex, and this complicates the assessment of treatment effects; therefore, we used the Z-score to evaluate changes in stature and craniofacial components. Growth in craniofacial structures and stature were both enhanced by rhGH therapy during orthodontic treatment.

Abnormalities in bone mineral density distribution and bone scintigraphy in patients with childhood onset hypopituitarism

The aim of our study was to evaluate the effects of long-life severe growth hormone deficiency on bone mineral density (BMD) and bone scintigraphy in adult patients with childhood onset (CO) hypopituitarism never treated with growth hormone. Our studies included 22 adult patients with CO hypopituitarism never treated with growth hormone (13 males and 9 females, aged 25-66 yr). The patients received replacement therapy with thyroxine, sex steroid hormones, and patients with secondary adrenocortical deficiency, hydrocortisone, but none of the patients had ever received GH treatment. In 22 patients, the total body with regional distribution of BMD, the lumbar spine L2-L4, and radial (33% site) BMD were determined by dual energy X-ray absorptiometry (DXA). In addition, 12 patients had the femoral neck BMD examined. In 10 cases, bone scintigraphy using 99-technetium labeled methylene diphosphonate was performed. Our studies revealed abnormalities, not yet described, in the regional distribution of BMD and bone scintigraphy in adults with CO hypopituitarism never treated with GH. In all patients, the results obtained from the total body showed definite disproportion in the regional distribution of BMD with a significantly advanced bone mineral deficit in the legs and a moderate deficit in the arms and total body. Local BMD measured at the radial (33% site) and lumbar spine L2-L4 revealed also a more pronounced bone mineral deficit in the cortical bone (33% distal radius) than in the trabecular bone (spine L2-L4). Bone scintigraphy showed a decrease in tracer accumulation in the shafts of the long bones but normal uptake in the spine, ribs, sternum, skull, and periarticular areas, indicating suppressed skeletal metabolism of cortical bone. Our studies indicate that long-life growth hormone deficiency leads to deficient and abnormal distribution of bone mineralization, a more pronounced deficit of BMD at the cortical bone, mainly expressed in the shafts of the long bones of the legs and arms, and moderately reduced BMD at the trabecular bone. Bone scans displaying low diphosphonates uptake in the shafts of the long bones point to greatly suppressed skeletal metabolism of the cortical bone in the patients with CO hypopituitarism never treated with GH.

Elevated IGFBP-1 cause high bone turnover in growth-restricted monochorionic twins with discordant birth weight

OBJECTIVE

To test the hypothesis that low birth weight twins have a higher risk of osteoportotic fracture in later life, we investigated the association between fetal IGF axis and type-1 collagen markers of bone turnover in monochorionic (MC) twins with or without discordant birth weight of >or=20%.

METHODS

Maternal and cord bloods were collected from gestational age matched MC twins of discordant (n = 16) and concordant birth weights (n = 16). The samples were assayed for cross linked carboxyl terminal telopeptide (ICTP, a marker of bone resorption) and pro-peptide (PICP, a marker of bone formation) of type I collagen, IGF-1, and IGFBP-1 by radio-immunoassay.

RESULTS

The growth-restricted twins (IUGR) of discordant group had higher fetal IGFBP-1 and ICTP (P < 0.001) levels, while PICP (P < 0.001) was lower than the co-twins with normal weight (AGA). In contrast, cord blood levels of IGF-1, IGFBP-1, ICTP, and PICP in concordant twin pairs were comparable to AGA twins. The concordant and AGA twins had a positive correlation between ICTP and PICP levels (y = 23x - 711; r = 0.84; P < 0.001; n = 48) but no such association was found in IUGR twins. Instead, IGFBP-1 levels in IUGR twins had a negative association with PICP (r = 0.81; P < 0.001; n = 16) and a positive correlation with ICTP (r- = 0.51; P < 0.05; n = 16). No such association was found in concordant and AGA twins.

CONCLUSION

These data suggest that growth-restricted twins had high bone turnover, due to elevated IGFBP-1. This association seems to be independent of maternal and genetic factors.

Calcium Supplementation Increases Bone Mass in GH-Deficient Prepubertal Children during GH Replacement

BACKGROUND/AIMS

Since GH plays an important role in bone mineralization, and several studies demonstrated the positive influence of a higher calcium intake on bone mass, we studied the effect of calcium supplementation in GHD children during GH therapy.

METHODS

28 prepubertal GHD children, 5.0-9.9 years old, were assigned to two groups: group A (n = 14; 7 females) treated with GH, and group B (n = 14; 7 females) treated with GH + calcium gluconolactate and carbonate (1 g calcium/day per os). Auxological parameters, total bone mineral content (TBMC) and density (TBMD), leg BMC and BMD, lumbar BMD, fat mass (FM) and lean tissue mass (LTM), blood 25-hydroxyvitamin D (25-OHD), parathyroid hormone (PTH), osteocalcin (OC) and urinary N-terminal telopeptide of type I collagen (NTx) were determined at the start of therapy and after 1 and 2 years of treatment.

RESULTS

During the 2 years of the study, TBMC, TBMD, leg BMC and BMD (but not lumbar BMD) increased in both groups of patients, however after 2 years of treatment they were significantly higher in the calcium-supplemented group B than in group A (p < 0.05, for all parameters). At the start of therapy, in both groups of patients percentage FM was higher and total and leg LTM lower than in controls (p < 0.05 for each parameter). Thereafter, FM decreased and LTM increased and after 2 years they were both different from baseline (p < 0.05). After 2 years of treatment, leg BMC and BMD were more positively correlated with regional leg LTM in patients of group B (r = 0.834 and r = 0.827, respectively; p < 0.001) than in patients of group A (r = 0.617 and r = 0.637, respectively; p < 0.05). 25-OHD and PTH levels were in the normal range in all patients at the start and during treatment. OC levels were lower and urinary NTx levels higher in patients than in controls (p < 0.05 for both parameters), either at the start and after 1 year of treatment. After 2 years of treatment, OC levels were significantly higher than at the start of the study (p < 0.05) in both groups of patients, but they were higher in group B than in group A (p < 0.05); on the contrary, urinary Ntx levels were lower in group B than in group A (p < 0.05).

CONCLUSION

In GHD children, treated with GH, calcium supplementation improved bone mass; it may aid in reaching better peak bone mass and in protecting weight-bearing bones, usually completed in childhood to maximum levels, from risk of osteoporosis and fractures later in life.