New markers of bone and collagen turnover in children and adults with growth hormone deficiency

Vitamin D status in prepubertal children with isolated idiopathic growth hormone deficiency: effect of growth hormone therapy

Few studies, and with controversial results, analyzed vitamin D status in children before and after growth hormone (GH) treatment. Thus, we aimed to assess vitamin D status in prepubertal children with idiopathic growth hormone deficiency (GHD), and to evaluate the effect of GHD and GH treatment on vitamin D levels. Fifty prepubertal children with isolated GHD were compared with 50 controls. All were subjected to history, anthropometric assessment and measurement of 25 hydroxyvitamin D (25(OH)D), serum calcium, phosphorous, alkaline phosphatase and parathyroid hormone (PTH) at diagnosis and 1 year after GH therapy. Serum 25(OH)D levels <30 ng/mL and 20 ng/mL were defined as vitamin D insufficiency and deficiency, respectively. 25(OH)D was lower in cases than controls. Forty per cent of children with GHD were 25(OH)D insufficient and 44% deficient, while 16% were sufficient at baseline. There was a positive correlation between 25(OH)D and peak GH levels. Peak GH was a significant predictor of 25(OH)D levels. After 1 year of GH therapy, 25(OH)D increased (18.42±5.41 vs 34.5±10.1 ng/mL; P<0.001). Overall, 22% of cases remained insufficient and 24% deficient, with an increase in prevalence of children with normal levels (54%; P<0.001). 25(OH) correlated negatively with PTH (r=-0.71, P=0.01). In conclusion, hypovitaminosis D is prevalent in children with GHD and significantly improved 1 year after GH therapy. 25(OH)D should be assessed in children with GHD at diagnosis and during follow-up.

Biochemical markers of insulin-like growth factor-I misuse in athletes: the response of serum IGF-I, procollagen type III amino-terminal propeptide, and the GH-2000 score to the administration of rhIGF-I/rhIGF binding protein-3 complex

CONTEXT

The GH-2000 and GH-2004 research groups developed a method for detecting GH misuse in athletes based on the measurement of serum IGF-I and procollagen type III amino-terminal propeptide (P-III-NP). There are reports that IGF-I is also misused by athletes, but currently there is no internationally recognized test designed to detect recombinant human IGF-I misuse.

OBJECTIVE

The objective of the study was to examine the response of serum IGF-I, P-III-NP, and the GH-2000 score to recombinant human (rh) IGF-I/rhIGF binding protein-3 (IGFBP-3) administration in recreational athletes.

DESIGN AND SETTING

This was a randomized, double-blind, placebo-controlled rhIGF-I/rhIGFBP-3 administration study at Southampton General Hospital (Southampton, United Kingdom).

PARTICIPANTS

Fifty-six recreational athletes (26 women, 30 men) participated in the study.

INTERVENTION

Participants were randomized to treatment with low-dose (30 mg/d) or high-dose (60 mg/d) rhIGF-I/rhIGFBP-3 complex or placebo for 28 days. Blood was collected throughout the drug administration and washout periods. Serum IGF-I and P-III-NP were measured using commercial immunoassays and GH-2000 scores were calculated.

RESULTS

IGF-I, P-III-NP, and the GH-2000 score rose in response to both low- and high-dose rhIGF-I/rhIGFBP-3 administration. The relative maximum response of IGF-I (approximately 4-fold increase in women and men) was greater than that of P-III-NP (40%-50% increase in women, 35%-50% increase in men). The GH-2000 formulae, which incorporate IGF-I and P-III-NP results, detected up to 61% of women and 80% of men in the rhIGF-I/rhIGFBP-3 groups but, using IGF-I concentrations alone, the sensitivity increased to 94% in both women and men during the administration period.

CONCLUSIONS

The rise in P-III-NP after rhIGF-I/rhIGFBP-3 administration is small compared with that after rhGH administration. Although rhIGF-I/rhIGFBP-3 administration can be detected using the GH-2000 score method, a test based on serum IGF-I alone provides better sensitivity.

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

BACKGROUND AND AIM

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

SUBJECTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

[Growth hormone therapy in adult patients: a review]

Growth hormone deficiency (GHD) can frequently be expected in hypopituitarism of adult patients. If GHD is proven by dynamic testing of the somatotrophic axis, growth hormone substitution is useful for improving quality of life, body composition, bone and lipid metabolism, and myocardial function according to the criteria of evidence-based medicine and is admitted by most national health authorities. There are no other reasonable indications for growth hormone treatment in adulthood.

Serum procollagen type 1 amino-terminal propeptide (P1NP) as an early predictor of the growth response to growth hormone treatment: Comparison of intrauterine growth retardation and idiopathic short stature

There is no way to predict early the growth response to growth hormone (GH) treatment in short children with intrauterine growth retardation (IUGR) or idiopathic short stature (ISS).

OBJECTIVE

To evaluate the capacity of the procollagen type 1 amino-terminal propeptide (P1NP), a new marker of bone formation, to help in this prediction.

PATIENTS AND METHODS

Longitudinal study of 30 patients treated at 7.7 (range: 2.2-12.5) years for IUGR (n=16) or ISS (n=14) with GH (0.47 and 0.33 or 0.4mg/kg/week respectively). P1NP and insulin-like growth factor I (IGF I) were measured before and after 3-6 months of GH treatment.

RESULTS

Before treatment, IUGR patients were younger and shorter than ISS patients, but their other characteristics were similar. IGF I Z-score (ZS) and P1NP concentrations were positively correlated in the whole population (Rho=0.48; P=0.01). After 3-6 months of treatment, both concentrations increased in IUGR and ISS (P<0.01). They remained correlated only in ISS (Rho=0.54; P<0.05). P1NP before treatment was negatively correlated (Rho=-0.67, P=0.015) with the growth rate (SD) during the first year of treatment in ISS but not in IUGR; IGF I ZS was not. The changes in P1NP for the whole population over 3-6 months, but not the changes in IGF I ZS, were positively correlated with the growth rate (Rho=0.41, P=0.03).

CONCLUSIONS

Lower basal plasma P1NP concentrations predict better growth response to GH treatment during the first year in ISS children. Greater increases in its concentrations after 3-6 months of GH treatment may also predict a better growth response in both ISS and IUGR.

Osteopenia, physical activity and health-related quality of life in survivors of brain tumors treated in childhood

BACKGROUND

Osteopenia has been reported in children surviving acute lymphoblastic leukemia and brain tumors, apparently as a consequence of therapy. It has been suggested that cranial irradiation may play a role in the development of this complication. In order to explore that possibility, we examined survivors of brain tumors treated with and without radiation in childhood to investigate associations between radiation, osteopenia, physical activity, health status and overall health-related quality of life (HRQL).

PROCEDURE

Subjects were survivors of posterior fossa tumors (astrocytoma or medulloblastoma) or optic glioma, < 18 years of age at diagnosis and > 1 year off treatment. Measurements of growth velocity, body composition, bone densitometry, physical activity and HRQL were undertaken.

RESULTS

Twenty-five (62.5%) of the 40 eligible patients participated in the study. Of the 25 patients, 12 (48%) received radiation therapy (R group) while 13 received no radiation (NR group). Growth hormone (GH) deficiency had been detected in three subjects, one had completed GH therapy while two were still on hormone replacement. The prevalence of osteopenia was 44% in the entire group, and 67% versus 27% in the R and NR groups. Florid osteoporosis was present in 20% of the entire group, more than 40% of the R group but none of the NR group. A significant correlation (P < 0.01) was observed between overall HRQL and Z scores of bone mineral density (BMD) of the lumbar spine. Pain and ambulation/mobility utility scores correlated significantly (P < 0.05) with BMD, while levels of physical activity correlated (P < 0.05) with overall HRQL utility scores.

CONCLUSIONS

This pilot study demonstrates that in survivors of brain tumors treated in childhood, radiation therapy is associated with significant loss of bone mineral. Among these survivors, HRQL is less, pain is more severe and ambulation is more restricted in those with low BMD scores. The reduction in HRQL is reflected in diminished physical activity. A larger multi-center study is needed to confirm these results.

Safety and efficacy of growth hormone replacement therapy in adults

Limitless supplies of recombinant human growth hormone (GH) have been available for the last 20 years. During that period, studies have characterised the effects of GH deficiency in adults and the benefits of GH replacement therapy. Areas of greatest impairment and benefit are quality of life, skeletal health and cardiovascular risk factors including the serum lipid profile and body composition. By optimising GH replacement therapy at various stages of adult life, it is hoped that it will prevent the development of osteoporosis and reduce the mortality and morbidity associated with hypopituitarism. However, the primary indication for GH therapy in adults in England and Wales is quality of life. The benefits of GH treatment are sustained over several years, and long-term surveillance of patients continues.

Growth hormone replacement is important for the restoration of parathyroid hormone sensitivity and improvement in bone metabolism in older adult growth hormone-deficient patients

Alterations in PTH circadian rhythm and PTH target-organ sensitivity exist in adult GH-deficient (AGHD) patients and may underlie the pathogenesis of AGHD-related osteoporosis. GH replacement (GHR) results in increased bone mineral density, but its benefit in AGHD patients over 60 yr old has been debated. To examine the effect of age on changes in PTH circadian rhythm and target-organ sensitivity after GHR, we recruited 22 AGHD patients (12 were <60 yr of age, and 10 were >60 yr of age). Half-hourly blood samples were collected for PTH, calcium, phosphate, nephrogenous cAMP (marker of renal PTH activity), type-I collagenbeta C-telopeptide (bone resorption marker), and procollagen type-I amino-terminal propeptide (bone formation marker) before and after 1, 3, 6, and 12 months of treatment with GHR. Significant PTH circadian rhythms were present in both age groups throughout the study. After GHR, PTH decreased and nephrogenous cAMP, adjusted calcium, and bone turnover markers increased in both groups, suggesting increased PTH target-organ sensitivity. In younger patients, the changes were significant after 1 month of GHR, but, in older patients, the changes were delayed until 3 months, with maximal changes at 12 months. Older AGHD patients derive benefit from GHR in terms of improvement in PTH sensitivity and bone metabolism. Their response appears delayed and may explain why previous studies have not shown a positive effect of GHR on bone mineral density in older AGHD patients.

Clinical effects of growth hormone on bone: a review

Growth hormone (GH) stimulates bone turnover. Deficiency of GH due to hypopituitarism is related to low bone mineral density and increased fracture risk. GH substitution increases and thus normalizes bone mineral density in these patients, which is one of a number of arguments for GH substitution in hypopituitarism. In contrast, a possible therapeutic use of GH in idiopathic osteoporosis and glucocorticoid-induced osteoporosis is speculative and not established. Reduction of osteoporosis risk is an argument brought up for a use of GH in healthy elderly persons (anti-aging medicine). However, since only very limited data are available yet, this cannot be based on scientific evidence, and there are important concerns about the safety of use of GH in healthy elderly persons.

Combined evaluation of resting IGF-I, N-terminal propeptide of type III procollagen (PIIINP) and C-terminal cross-linked telopeptide of type I collagen (ICTP) levels might be useful for detecting inappropriate GH administration in athletes: a preliminary report

OBJECTIVE

To verify whether combined measurements of GH-dependent parameters might be useful in detecting exogenous recombinant GH (rGH) administration in male athletes from different disciplines.

METHODS

Sixty-six athletes (control group) were sampled for the evaluation of resting IGF-I, N-terminal propeptide of type III procollagen (PIIINP) and telopeptide type I collagen (ICTP). Cut-off values (mean + 2 SD) for IGF-I, PIIINP and ICTP were calculated and arbitrary scores (1.5, 2.0) were assigned to abnormal parameters. By using the sum of individual parameter scores, positive (> or = 3) or negative (< 3) scores were obtained. In addition, a subgroup of six athletes was treated for 3 weeks with rGH (0.09 IU/kg body weight, 6 days/week) and was similarly evaluated at the end of the 1st, 2nd and 3rd week (i.e. 18 samples).

RESULTS

Abnormal IGF-I, or PIIINP or ICTP levels were found, respectively, in one, two and four subjects (1.5-6.1%) of the control group (in the younger athletes); only one 19-year-old subject of this group obtained a positive score. Abnormal IGF-I, PIIINP and ICTP levels were found in 61.1-66.7% samples of the treated group. Positive cases were 3/6 at the 1st and 2nd week and 6/6 at the 3rd week. The sensitivity of the screening approach was 50-100% (at the 1st-2nd and 3rd week, respectively) and specificity was 98.5%.

CONCLUSION

This 'first level' screening test is safe, acceptable and relatively inexpensive. Further additional investigations of 'second level' (i.e. GH secretory profile, GH response to a GH-releasing peptide) can be retained to validate or exclude rGH administration or for the early diagnosis of infrequent endogenous GH hypersecretion.

Elite volunteer athletes of different sport disciplines may have elevated baseline GH levels divorced from unaltered levels of both IGF-I and GH-dependent bone and collagen markers: a study on-the-field

Seventy-seven Italian eliteathletes(42 M, 35 F, mean age +/- SE: 24.4-0.7 yr, age range: 17-47 yr) of different sport disciplines (sprinters, triathletes, middle-distance runners, road-walkers, cyclists, rowing athletes, skiers, roller hockey players, swimmers) were sampled on-the-field (before a training session) for the determination of basal GH, IGF-I, C-terminal cross-linked telopeptide of type I collagen (ICTP) and amino-terminal propeptide of type III procollagen (PIIINP) levels, two GH-dependent peripheral markers of bone and collagen turnover, respectively. Basal GH concentrations were significantly higher (p<0.001) in female (5.8 +/- 1.0 ng/ml) vs male athletes (1.8 +/- 0.5 ng/ml), with a large spread of values in either gender. Mean GH levels of athletes were significantly higher than those recorded in age-matched sedentary controls (females: 2.5 +/- 0.5 ng/ml, p<0.001; males: 0.5 +/- 0.2 ng/ml, p<0.05). Among female athletes, 7/35 had basal GH values higher than the upper limit of control values (>9.5 ng/ml), while among males 7/42 had values higher than the upper limit of male sedentary controls (>3.6 ng/ml). No significant differences in basal GH concentrations were found between females taking oral contraceptives (OC) and those who did not receive this treatment (5.0 +/- 2.1 vs 6.0 +/- 1.2 ng/ml). IGF-I levels (236.4 +/- 7.8 ng/ml) were in the normal range for age in all athletes (except for 1 athlete with slightly increased levels), no significant correlation being found between GH and IGF-I levels (R2=0.0393). Mean ICTP (4.6 +/- 0.2 ng/ml) and PIIINP (4.4-0.1 ng/ml) concentrations of elite athletes were not significantly different from those recorded in age and matched healthy sedentary subjects; 4 athletes showed increased PIIINP levels and 2 had increased ICTP levels. ICTP and PIIINP levels were positively correlated with chronological age (p<0.001), a positive correlation being also found between the two markers (p<0.001). On the contrary, no significant correlation was found between basal GH/IGF-I levels and ICTP/PIIINP levels. In conclusion, the present study demonstrates that: 1) elite athletes (particularly females), which have frequently increased basal GH on-the-field, have actually normal IGF-I levels; 2) ICTP and PIIINP levels of athletes are similar to those recorded in healthy sedentary, being significantly higher in younger subjects of both groups; 3) the presence of increased basal GH levels, being associated with normal IGF-I, ICTP and PIIINP levels, is probably the result of a transient GH peak in this study group. Further additional studies are requested to verify the possible use of these peripheral GH-dependent markers for detecting exogenous chronic administration of recombinant GH in athletes.

IGF -I plasma concentrations in non-treated horses and horses administered with methionyl equine somatotropin

Insulin-like growth factor-I (IGF -I) is likely to be an indicator of somatotropin (ST) administration in the horse. To investigate the different ways ST administration may be detected, the following aspects of IGF -I concentrations in plasma were studied: (i) the daily variation; (ii) variation following a treadmill test; (iii) concentrations at rest and after exercise; and (iv) concentrations in plasma from two young horses and two adults treated with methionyl equine somatotropin (e ST). In the population of horses at rest, IGF -I mean concentration (SEM) was 261 (104) ng ml(-1). In post race samples, IGF -I mean concentration was 187 (100) ng ml(-1). All of these data indicate that exercise does not modify IGF -I concentration in plasma. The magnitude of the increase in IGF -I following administration of e ST differed according to the age of the horses. The critical value of 700 ng ml(-1)was exceeded for 1 day in adult horses and for at least 11 days in young horses. These results show that IGF -I has potential as an indirect marker of ST administration in horses.

The effect of growth hormone on insulin-like growth factor I and bone metabolism in distraction osteogenesis

Limb lengthening in the left tibia of 30 mature female Yucatan micropigs was performed using distraction osteogenesis. A treatment group of 15 animals received recombinant porcine growth hormone (r-pGH) (100 microg/kg/day) while the others served as controls. Serial serum measurements of total insulin-like growth factor I (IGF-I), free IGF-I, IGF binding proteins -1, -2, -3 and -4 (IGFBP-1 to -4) were performed. Bone-specific alkaline phosphatase (bone-ALP) and the serum carboxyl-terminal telopeptide of type I collagen (ICTP) were measured as bone turnover markers. The GH-treated animals showed a significant increase in total IGF-I, free IGF-I and IGFBP-3 after surgery (P<0.001). Similarly, the treated animals showed a significantly higher level of bone-ALP (P<0.001) throughout the experiment compared to the controls. There was a significant correlation between bone-ALP and total IGF-I (r=0.76) in the GH-treated group and an even higher correlation for free IGF-I (r=0.90). There was no difference in the ICTP serum levels between the two groups. These data indicate that the application of species-specific growth hormone results in a stimulation of bone formation in distraction osteogenesis which may be mediated by IGF-I. The stronger correlation between free IGF-I and bone-ALP indicates that the anabolic effect of IGF-I may be regulated through the IGFBPs by binding and inactivating IGF-I.

Optimizing gh therapy in adults and children

Until the advent of modern neuroradiological imaging techniques in 1989, a diagnosis of GH deficiency in adults carried little significance other than as a marker of hypothalamo-pituitary disease. The relatively recent recognition of a characteristic clinical syndrome associated with failure of spontaneous GH secretion and the potential reversal of many of its features with recombinant human GH has prompted a closer examination of the physiological role of GH after linear growth is complete. The safe clinical practice of GH replacement demands a method of judging overall GH status, but there is no biological marker in adults that is the equivalent of linear growth in a child by which to judge the efficacy of GH replacement. Assessment of optimal GH replacement is made difficult by the apparent diverse actions of GH in health, concern about the avoidance of iatrogenic acromegaly, and the growing realization that an individual's risk of developing certain cancers may, at least in part, be influenced by cumulative exposure to the chief mediator of GH action, IGF-I. As in all areas of clinical practice, strategies and protocols vary between centers, but most physicians experienced in the management of pituitary disease agree that GH is most appropriately begun at low doses, building up slowly to the final maintenance dose. This, in turn, is best determined by a combination of clinical response and measurement of serum IGF-I, avoiding supraphysiological levels of this GH-dependent peptide. Numerous studies have helped define the optimum management of GH replacement during childhood. The recent requirement to measure and monitor GH status in adult life has called into question the appropriateness of simplistic weight- and surface area-based dosing regimens for the management of GH deficiency in childhood, with reliance on linear growth as the sole marker of GH action. It is clear that the monitoring of parameters other than linear growth to help refine GH therapy should now be incorporated into childhood GH treatment protocols. Further research will be required to define the optimal management of the transition from pediatric to adult GH replacement; this transition will only be possible once the benefits of GH in mature adults are defined and accepted by pediatric and adult endocrinologists alike.

Effects of 12-month GH treatment on bone metabolism and bone mineral density in adults with adult-onset GH deficiency

Serum bone-Gla protein (BGP), bone alkaline phosphatase (B-AP), and C-terminal cross-linked telopeptide of type I collagen (ICTP) levels were evaluated in 18 adults with acquired GH deficiency (GHD, 14 males and 4 females, age range: 25-59 yr) before, at 3, 6, 9 and 12 months of rec-GH treatment (0.125 IU/kg/week for the first month, followed by 0.25 IU/kg/week for 11 months) and 6 months after the withdrawal of therapy. Total body bone mineral density (BMD, g/cm2) was measured with dual energy X-ray absorptiometry (Hologic QDR 1000/W) before, at 12 months of GH treatment and 6 months after its withdrawal. Before treatment, BGP (mean+/-SE: 5.1+/-0.4 ng/ml), B-AP (59.4+/-6.5 IU/l), ICTP (3.1+/-0.3 ng/ml) levels of patients were similar to in healthy controls (BGP: 5.4+/-0.1 ng/ml; B-AP: 58.2+/-2.0 IU/l; ICTP: 4.1+/-0.3 ng/ml). GH treatment caused a significant increase of BGP, B-AP, ICTP levels, the maximal stimulation of bone resorption, occurring after 3 months of GH treatment, while the maximal effect on bone formation being evident later (at 6th month). A slight decline in BGP, B-AP, T-AP and ICTP levels occurred at 9-12 months of therapy, although the values remained significantly higher than in basal conditions and with respect to healthy controls. Before treatment, mean total body BMD of patients (1.110+/-0.027 g/cm2, range: 0.944-1.350 g/cm2) was not significantly different (z-score: +0.47+/-0.31, NS) from that observed in healthy controls (1.065+/-0.008 g/cm2, range: 1.008-1.121 g/cm2). GH therapy was associated with a significant reduction of mean total body BMD values (6th month: -1.8+/-0.5%, p<0.01; 12th month: -2.1+/-1.0%, p<0.05 vs baseline), particularly evident in the first six months of treatment. Six months after the withdrawal of GH therapy, BGP (5.9+/-0.5 ng/ml), B-AP (57.3+/-7.0 IU/l) and ICTP (3.2+/-0.1 ng/ml) levels returned similar to those recorded before treatment, while total BMD increased (+1.5+/-0.7, p<0.05), remaining however slightly lower than in basal conditions (-0.6+/-1.2, NS). In conclusion, our study shows that: a) acquired GHD in adulthood is associated with both normal bone formation/resorption indexes and normal total body BMD; b) GH therapy causes a significant rise of bone formation/resorption markers (earlier and greater for bone resorption); c) one-year GH therapy is associated with a reduction of total body BMD values, particularly evident in the first 6 months of treatment; d) the effects of GH therapy on bone turnover are transient, being completely reverted six months after the withdrawal of GH therapy; e) the increase of total body BMD (up to baseline values) after GH withdrawal might be explained as consequence of persisting effects of previous GH stimulation on bone remodeling.

Effects of 12 months rec-GH therapy on bone and collagen turnover and bone mineral density in GH deficient children with thalassaemia major

Children suffering from thalassaemia major are reported to have growth delay and bone alterations even when well transfused and chelated. In the present study we evaluated bone and collagen turnover (bone Gla-protein, BGP; carboxyterminal telopeptide of type I collagen, ICTP; aminoterminal propeptide of type III procollagen, PIIINP, respectively) and bone mineral density (BMD) in 5 pre-pubertal GH deficient thalassaemic children before and during rec-GH treatment (0.6 IU/kg/week). Data were compared with those recorded in an age- and sex-matched control group. Before treatment, serum BGP and ICTP levels were significantly lower (p<0.0001) in children with thalassaemia (9.3+/-0.7 ng/ml and 5.3+/-0.5 ng/ml, respectively) than in healthy controls (18.9+/-0.9 ng/ml and 14.4+/-0.6 ng/ml, respectively), while serum PIIINP levels did not significantly differ in the two groups (6.7+/-0.7 ng/ml vs 6.7+/-0.7 ng/ml). Mean lumbar BMD values of patients (0.62+/-0.05 g/cm2) were significantly lower (p<0.05) than those recorded in healthy controls (0.78+/-0.01 g/cm2), while femoral BMD values were similar in the two groups (patients: 0.70+/-0.08 g/cm2 vs controls: 0.74+/-0.01 g/cm2). One-year GH therapy significantly increased height velocity (from 2.3+/-0.2 cm/year to 6.1+/-0.4 cm/yr, p<0.0001) and IGF-I levels (from 61.6+/-15.4 to 342+/-38.5 ng/ml, p<0.005). Serum BGP (basal: 9.3+/-0.7 ng/ml, 6th month: 10.8+/-0.6 ng/ml, 12th month: 14.9+/-1.4 ng/ml), ICTP (basal: 5.3+/-0.5 ng/ml, 6th month: 7.9+/-0.8 ng/ml, 12th month: 10.9+/-1.7 ng/ml) and PIIINP levels (basal: 6.7+/-0.7 ng/ml, 6th month: 9.9+/-1.0 ng/ml, 12th month: 9.6+/-1.4 ng/ml) significantly increased (p<0.05), while no significant effects were observed on lumbar and femoral BMD values. Although the GH-induced stimulation of bone turnover markedly increased BGP (+60%) and ICTP (+105%) levels, one-year GH therapy was not sufficient to completely normalize these parameters, which remained significantly lower than in healthy controls. In conclusion, our study shows that pre-pubertal GH deficient children with thalassaemia major have reduced bone turnover (both bone formation and resorption) and lumbar BMD values, thus indicating that bone metabolism should be monitored and improved even in well-transfused patients. One-year GH treatment is able to increase, but not normalize, bone turnover, this effect being insufficient to improve BMD values. More prolonged periods of GH therapy are probably requested to positively affect both bone turnover and BMD values in GH deficient thalassaemic patients, as occurs in children and adults with GH deficiency.

Effects of 12 months rhGH treatment on bone and collagen turnover in children with constitutional growth delay

Serum bone Gla protein (BGP), marker of osteoblast function, serum carboxyterminal cross-linked telopeptide of type I collagen (ICTP) and urinary free deoxypyridinoline (DPD), markers of bone resorption, and the aminoterminal propeptide of type III procollagen (PIIINP), marker of type III collagen turnover, were determined in eight prepubertal children (8 males, age range 7-9.6 yr, Tanner stage I) with constitutional growth delay (CGD), before and after 6-12 months of treatment with rhGH (Saizen, Serono, 0.6 IU/kg/week, s.c.). Serum BGP (mean+/-SD: 15.4+/-1.7 ng/ml), ICTP (9.4+/-1.6 ng/ml) and urinary DPD/creatinine (11.3+/-1.7 nmol/mmol) levels were significantly lower (p<0.02, p<0.0001 and p<0.02, respectively) in children with CGD than in healthy age-matched controls (BGP: 18.9+/-3.6 ng/ml, ICTP: 14.3+/-2.6 ng/ml, DPD: 20.7+/-10.0 nmol/mmol), while PIIINP levels of patients were similar to those recorded in controls (6.3+/-0.7 vs 6.7+/-2.3 ng/ml, respectively). Serum BGP, urinary free DPD/creatinine and PIIINP levels significantly increased after 6 (BGP: 20.9+/-2.1 ng/ml, p<0.0001; DPD/creatinine: 16.3+/-3.6 nmol/mmol, p<0.001; PIIINP: 8.1+/-1.6 ng/ml, p<0.005) and 12 months (BGP: 19.2+/-2.0 ng/ml, p<0.0001; DPD/creatinine: 19.7+/-5.1 nmol/mmol, p<0.001; PIIINP: 8.8+/-1.9 ng/ml, p<0.002) of GH treatment. Serum ICTP levels did not significantly change after 6 months (10.6+/-2.1 ng/ml), while a significant increase (p<0.002) was evident after 12 months of therapy (13.6+/-1.3 ng/ml). Our study shows that BGP, ICTP and DPD/creatinine levels are significantly reduced in children with CGD, thus indicating the presence of low bone turnover in this form of short stature. Since GH treatment is able to reactivate bone remodeling and increase collagen synthesis, it is tempting to speculate that a partial GH-IGF-I defect (i.e. locally at bone level) might be one of the factors involved in determining the biochemical alterations of bone metabolism found in this clinical condition.

Long-term monitoring of rec-GH treatment by serial determination of serum aminoterminal propeptide of type III procollagen in children and adults with GH deficiency

Serum aminoterminal propeptide of type III procollagen (PIIINP) levels, a reliable marker of collagen formation, were evaluated in children (C=7) and adults with childhood-onset (CO=10) and acquired (A=18) GH deficiency (GHD) before, during and after withdrawal of rec-GH therapy (C=0.6 IU/kg/week, CO=0.5 IU/kg/week, A=0.25 IU/kg/week). The duration of treatment was 12 months for C and A and 6 months for CO; investigations were carried out before and at 3, 6, 9 and 12 months (for C and A) and at 3 and 6 months (for CO) of GH treatment and 6 months after the withdrawal of therapy (for A and CO). Data obtained from patients were compared with those recorded in two age- and sex-matched control groups. Before treatment, serum PIIINP levels were significantly lower (p<0.001) in C with GHD (mean+/-SE: 2.9+/-0.4 ng/ml) than in controls (6.1+/-0.4 ng/ml), while no significant differences were recorded between adults with CO/A-GHD (3.7+/-0.5 ng/ml and 3.4+/-0.2 ng/ml) and controls (3.2+/-0.2 ng/ml). GH treatment caused a significant increase (p<0.0001) of PIIINP levels both in C (3rd month: 4.4+/-0.2 ng/ml, 6th month: 5.1+/-0.4 ng/ml, 12th month: 5.1+/-0.5 ng/ml), CO-GHD (3rd month: 12.7+/-1.2 ng/ml; 6th month: 10.2+/-0.6 ng/ml) and A-GHD (3rd month: 10.0+/-1.0 ng/ml; 6th month: 8.4+/-0.6 ng/ml; 12th month: 7.0+/-0.7 ng/ml), the increase being dose-dependent (more marked and sustained in adults with CO-GHD). The maximal stimulation of collagen synthesis occurred after 3 months of GH treatment in adults with GHD, while a more gradual and less relevant increase was observed in C with GHD. Six months after the withdrawal of GH therapy, serum PIIINP levels of adults with CO-GHD (3.6+/-0.3 ng/ml) were similar to those recorded before treatment, while in adults with A-GHD serum PIIINP levels (2.6+/-0.2 ng/ml) were significantly lower (p<0.01) than in basal condition. In conclusion, our study shows that: a) GHD is associated with a reduction of soft tissue formation in children, while it seems to exert no relevant effects in adults with GHD; b) GH therapy causes a rapid stimulation of collagen turnover, which shows a different pattern in children and adults; c) the GH-induced stimulation of collagen synthesis is rapidly removed after the withdrawal of GH treatment. For these reasons, the determination of peripheral markers of GH effects appears useful for the monitoring of GH therapy and can contribute to assess the "tailored" substitutive dose for the individual patient.

Effect of long-term treatment with GH on bone metabolism, bone mineral density and bone elasticity in GH-deficient adults

OBJECTIVE

Adults with GH deficiency (GHD) commonly have subnormal bone mineral density (BMD), and have been reported to have an increased risk of fractures. It has been suggested that GH replacement therapy may have beneficial effects on bone in such patients. The aim of this study was to investigate the effects of long-term GH replacement therapy on bone metabolism, BMD and bone elasticity in adults with GHD.

DESIGN

At the start of the study, 20 adults with GHD were randomized to receive either GH, 0.25 IU/kg/week (the 'GH group') or placebo (the 'placebo group'). After 6 months, patients in the placebo group were switched to GH therapy, and all patients received GH for a further 42 months.

PATIENTS

Of the 20 patients included in the study, 11 were male and nine were female. Mean age at the start of the study was 42.5 +/- 10.1 years. All patients had been GH-deficient for at least 2 years before the start of the study.

MEASUREMENTS

Rates of bone resorption and formation were assessed by measuring serum levels of type I collagen carboxyterminal cross-linked telopeptide (ICTP) and carboxyterminal propeptide of type I procollagen (PICP), respectively. BMD was measured at the lumbar spine by dual-photon absorptiometry (DPA) and at the non-dominant forearm by single-photon absorptiometry (SPA). Bone elasticity was assessed by measuring apparent phalangeal ultrasound transmission velocity (APU).

RESULTS

The main results in the GH group were as follows. The rate of bone resorption increased significantly during the first 6 months of treatment and remained significantly elevated above its baseline level thereafter. The rate of bone formation also rose during the first 6 months of treatment and remained elevated thereafter, but was significantly higher than at baseline only after 24 months of treatment. At both sites measured, BMD was subnormal at baseline, decreased during the first 6 months of treatment, and increased progressively for the rest of the study, eventually rising well above its baseline level. Bone elasticity decreased during the first 6 months of treatment, but had returned to its baseline level after 24 months.

CONCLUSIONS

Our results support previous findings that BMD is subnormal in adults with GHD, that GH replacement therapy can stimulate bone turnover in such adults and that, in the long term, such stimulation results in a significant increase in BMD. In addition they show, for the first time, that BMD may continue to rise even after GH replacement therapy has been administered for 4 years, and indicate that bone elasticity is not adversely affected by long-term GH therapy.

Osteopenia in children surviving brain tumours

Osteopenia has been reported in children surviving acute lymphoblastic leukaemia, apparently as a consequence of therapy. It has been suggested that cranial irradiation may play a crucial role in this disorder. To explore that possibility, survivors of brain tumours in childhood, all of whom had received radiotherapy, were examined for evidence of bone mineral loss. 19 children were assessed, on average at 7 years after treatment. Measurements of growth velocities, plain radiography of the skeleton, bone densitometry, health-related quality of life and physical activity were undertaken. Growth hormone (GH) deficiency had been detected in 6 children and 5 had received GH replacement, for a minimum of more than 3 years. 9 children were radiographically osteopenic (including the 5 who had received GH). Z scores for bone mineral density (BMD) were negative in the majority of children. Health-related quality of life was less and pain more frequent in those with low BMD scores. Pain was correlated negatively with both free-time activity and seasonal activity (P < 0.01). Osteopenia is a common sequel of therapy in children with brain tumours. Those with osteopenia have more pain and more compromised, health-related quality of life than those who are not osteopenic, and pain significantly limits physical activity. The pathogenesis of osteopenia in these children is still uncertain, but is likely to be multifactorial.

Intestinal calcium absorption and bone metabolism in young adult men with childhood-onset growth hormone deficiency

Suboptimal growth hormone (GH) replacement therapy during childhood is a major cause of osteopenia in young adults with childhood-onset GH deficiency (CO-GHD). This is primarily attributed to reduced bone formation in childhood. It is currently not known whether GHD also has adverse effects on bone metabolism in adult life. To examine the impact of GHD on calcium and bone metabolism in adults, we evaluated 50 men with CO pituitary failure at a mean age of 28.2+/-4.5 years, i.e., 8.8+/-4.1 years after the discontinuation of previous GH treatment for short stature. Thirty-three patients had multiple pituitary hormone deficiencies (MPHD) for which they received conventional replacement therapy, seventeen patients had isolated GHD (IGHD), and forty-nine age-matched men served as controls. Intestinal calcium absorption, serum calcium concentration, serum phosphate levels, and renal calcium and phosphate excretion were normal in IGHD and MPHD patients. IGHD patients had marginally elevated serum levels of the carboxy-terminal cross-linked telopeptide of type I collagen (ICTP: 5.0+/-1.2 vs. 4.2+/-1.2 microg/l, p < 0.05), but other indices of bone turnover were normal. In contrast, MPHD patients had reduced levels of the carboxy-terminal propeptide of type I procollagen (PICP: 137+/-76 vs. 179+/-72 microg/l, p < 0.01), elevated serum ICTP levels (6.0+/-3.8 vs. 4.2+/-1.2 microg/l, p < 0.001), and reduced serum 1,25-dihydroxyvitamin D levels (55.1+/-16.7 vs. 73.0+/-23.0 pmol/l, p < 0.001). Multivariate regression analysis showed that the serum levels of bone resorption and bone formation markers in MPHD patients were correlated with the hydrocortisone, thyroxine, and testosterone replacement doses. There was no relationship with serum insulin-like growth factor I concentration. Panhypopituitary adults receiving conventional hormone replacement therapy are at risk to develop osteopenia either caused by reduced bone formation or by increased bone resorption activity. Predominantly, these abnormalities result from nonoptimal thyroid, gonadal, or adrenal hormone replacement therapy. GHD is not an important factor. In adults, GHD does not adversely affect intestinal calcium absorption or bone formation activity. Bone resorption activity may be slightly higher than normal, but the abnormality is too small to expect substantial bone loss as a consequence of GHD.

Effects of recombinant growth hormone (GH) treatment on bone mineral density and body composition in adults with childhood onset growth hormone deficiency

Lumbar spine, whole proximal femur and total body bone mineral density (BMD, g/cm2) and the regional soft tissue composition were measured with dual energy X-ray absorptiometry (Hologic QDR 1000/W) in eight adults with childhood onset GHD, before and after 6 months of recombinant GH treatment (0.5 IU/kg/week). Data obtained from patients were compared with those recorded in an age and sex matched control group. Before treatment, lumbar (L2-L4) spine BMD (mean +/- SD: 0.811 +/- 0.159 g/cm2), whole proximal femur BMD (0.739 +/- 0.094 g/cm2) and total body BMD (0.946 +/- 0.087 g/cm2) of patients were significantly (p < 0.001, 0.01 and 0.001, respectively) lower than those recorded in an age- and sex-matched control group (1.077 +/- 0.155 g/cm2, 0.968 +/- 0.166 g/cm2 and 1.168 +/- 0.058 g/cm2, respectively), although three patients showed BMD values at the lower limit of the normal range. Mean lumbar spine BMD, whole proximal femur BMD and total body BMD did not significantly change alter 6 months' GH treatment (-1.4 +/- 3.7%, +2.7 +/- 3.7% and -1.1 +/- 5.0% vs basal values, respectively). On the other hand, trochanteric subregion showed a significant 4.8 +/- 5.3% increase (vs basal, p < 0.05), while other hip subregions did not show significant changes. GH therapy caused marked effects on body composition; in fact, a significant decrease (p < 0.01) of trunk fat (-25.2 +/- 15.0%) and a marked increase (p < 0.01) of limbs lean mass (+10.0 +/- 5.3%), resulting in a significant (p < 0.02) reduction (-16.5 +/- 13.5%) of the axial to peripheral fat ratio (APFR), were clearly evident after six months of therapy. In conclusion, our study shows that six months of GH treatment do not exert relevant effects on the BMD of adults with childhood onset GHD. On the contrary, the effects of GH therapy on body composition are more marked, being clearly appreciable after six months of treatment.

Serum bone Gla protein and carboxyterminal cross-linked telopeptide of type I collagen in patients with Cushing's syndrome

Serum bone Gla protein, a marker of bone formation, and carboxyterminal cross-linked telopeptide of type I collagen levels, an index of bone resorption, were evaluated in eight patients with active Cushing's syndrome and in four with 'preclinical' Cushing's syndrome, before and after surgery. In basal conditions, serum bone Gla protein levels were significantly lower (p < 0.0001) in patients with active Cushing's syndrome (1.0 +/- 0.35 ng/ml) than in controls (5.4 +/- 0.15 ng/ml); two out of four patients with the 'preclinical' form had reduced bone Gla protein levels, while in the other two cases levels were in the normal range. Serum levels of carboxyterminal cross-linked telopeptide of type I collagen (3.0 +/- 0.4 ng/ml), although slightly reduced, were similar to those recorded in controls (4.1 +/- 0.3 ng ml), both in patients with active and with preclinical Cushing's syndrome. After surgery serum levels of both marker proteins significantly increased in seven out of eight patients with active Cushing's syndrome; in one patient, who was not cured after surgery, bone Gla proteins levels remained lower than in normals, while levels of carboxyterminal cross-linked telopeptide of type I collagen had a transient increase after six months. In the two patients with a 'preclinical' Cushing's syndrome who underwent surgery, a significant rise of the levels of both marker proteins was observed, similar to that observed in patients with active Cushing's syndrome. It was concluded that serial determinations of these new markers of bone formation and resorption may be usefully employed to follow-up the clinical course of Cushing's syndrome and provide information on the rate of bone turnover in response to medical and/or surgical therapies. Moreover, the evaluation of these markers in preclinical states of Cushing's syndrome might suggest the need for surgery.

Modifications of biochemical markers of bone and collagen turnover during corticosteroid therapy

Serum bone Gla protein (BGP), carboxyterminal cross-linked telopeptide of type I collagen (ICTP) and aminoterminal propeptide of type III procollagen (PIIINP) levels were determined in 8 patients with autoimmune disorders (2 with systemic lupus erythematosus, 3 with rheumatoid arthritis, 2 with Sjögren's syndrome and 1 with mixed connective tissue disease) before and after 1, 2 and 4 months of treatment with oral prednisone (at a dosage of 1 mg/kg bw/day, p.o. during the first month, then reduced to 0.1-0.2 mg/kg bw/day). Before treatment mean serum BGP (mean +/- SE: 5.3 +/- 0.4 ng/ml) and ICTP (2.8 +/- 0.2 ng/ml) levels were similar to those recorded in an age and sex matched control group (n = 40: 5.4 +/- 0.1 ng/ml and 4.1 +/- 0.3 ng/ml, respectively). On the other hand, serum PIIINP levels (2.2 +/- 0.3 ng/ml) were significantly (p < 0.008) lower than those found in controls (3.3 +/- 0.2 ng/ml). During glucocorticoid therapy, serum BGP levels significantly decreased after 1 month (2.9 +/- 0.4 ng/ml; P < 0.001), but returned to baseline values after 2 and 4 months of treatment (4.7 +/- 0.4 ng/ml and 5.3 +/- 0.3 ng/ml, respectively). On the contrary, no significant changes were observed in serum ICTP levels during treatment (1st month: 2.7 +/- 0.4 ng/ml; 2nd month: 3.0 +/- 0.4 ng/ml; 4th month: 2.4 +/- 0.3 ng/ml). Serum PIIINP mean concentration significantly decreased after 1 (1.6 +/- 0.3 ng/ml; P < 0.004) and 2 months of glucocorticoid administration (1.5 +/- 0.2 ng/ml; P < 0.01); after 4 months, serum PIIINP levels were again reduced as before therapy (1.8 +/- 0.2 ng/ml). In conclusion, our study shows the presence of normal bone turnover indexes and of altered collagen synthesis in patients with autoimmune disorders. The use of high doses of oral steroids is associated with a prompt decrease of bone formation and collagen synthesis, without any significant changes in bone resorption; however, the negative effects on bone formation and collagen synthesis seem to revert after lowering corticosteroid dosage. Serial determinations of the markers of bone and collagen turnover are able to give useful and reliable information on the peripheral effects of steroids excess.

Serum levels of carboxyterminal propeptide of type I procollagen and pyridinoline crosslinked telopeptide of type I collagen in normal children and children with growth hormone (GH) deficiency during GH therapy

In this study, we investigated age-related changes in serum levels of both the carboxyterminal propeptide of type I procollagen (PICP) and the pyridinoline crosslinked telopeptide of type I collagen (ICTP) to elucidate bone formation and resorption, respectively, in 200 normal Japanese children (141 males and 59 females, age range 0-16 years). Furthermore, to clarify the effect of GH on bone turnover, we measured serum PICP and ICTP in 26 growth hormone (GH)-deficient children (20 males and 6 females, age range 4-15 years) who showed significant bone growth during recombinant human GH therapy. In the normal children, the curves for age-related changes in both serum PICP and ICTP levels almost paralleled that of the standard height velocity curve in both sexes. The serum levels of both peptides were higher than those in adults, and the peak increases corresponded with the timing of the adolescent growth spurt. Furthermore, the serum levels of PICP and ICTP were significantly correlated with the height velocity. In the GH-deficient patients, the serum ICTP levels before GH therapy were lower than those in age- and sex-matched controls. Both PICP and ICTP levels in serum increased significantly at the beginning of GH therapy. Furthermore, the percent increase in PICP after 1 month of GH treatment was positively correlated with the percent increase in height velocity during 1 year of GH treatment.(ABSTRACT TRUNCATED AT 250 WORDS)