Influence of two different GH dosage regimens on final height, bone geometry and bone strength in GH-deficient children

The effect of two different GH dosages on final height and bone geometry

Background

Growth hormone (GH) has a strong positive influence on bone, stimulating both bone elongation and increase in size. The aim of the study was to compare the effect of two different GH dosages on final height and bone geometry in two groups of GH-deficient children.

Methods

We evaluated 121 children (86 m, 35f). Group 1 (77 patients) treated with GH at a mean dose of 0.16 mg/kg/week and group 2 (44 patients) at 0.3 mg/kg/week. Bone geometry was evaluated at final height from a digitalized X-ray of the left hand considering the following parameters: metacarpal index (MI), cross-sectional area (CSA), cortical area (CA) and medullary area (MA).

Results

At baseline, group 2 was shorter than group 1 (−1.54 vs −1.01 SDS; p < 0.005), while at final height there was no difference. Height gain was significantly greater in group 2 than in group 1 (1.62 vs 1.13 SDS; p < 0.001). Bone geometry: MI was significantly greater in group 2 (0.62 vs 0.55; p < 0.001) as well as CA (46.87 vs 42.69 cm²; p < 0.005), while MA was significantly lower in group 2 (8.48 vs 11.65 cm²; p < 0.002).

Conclusion

Higher GH doses elicit a significantly greater statural gain and a greater bone cortical area.

The Effect of Recombinant Growth Hormone Treatment in Children with Idiopathic Short Stature and Low Insulin-Like Growth Factor-1 Levels

OBJECTIVE

Idiopathic short stature (ISS) constitutes a heterogeneous group of short stature which is not associated with an endocrine or other identifiable cause. Some ISS patients may have varying degrees of insulin-like growth factor-1 (IGF-1) deficiency. Recombinant growth hormone (rGH) treatment has been used by some authors with variable results. Reports on long-term rGH treatment are limited.

METHODS

In this study, 21 slowly growing, non-GH-deficient ISS children who received rGH treatment for 3.62±0.92 years were evaluated at the end of a 5.42±1.67-year follow-up period. The study group included patients with low IGF-1 levels who also responded well to an IGF generation test. The patients were divided into two groups as good responders [height increment >1 standard deviation (SD)] and poor responders (height increment <1 SD) at the end of the follow-up period.

RESULTS

The height of the patients improved from -3.16±0.46 SD score (SDS) to -1.9±0.66 SDS. At the end of the follow-up period, mean height SDS was -1.72. Eleven of the patients showed a good response to treatment. Clinical parameters were essentially similar in the good responders and the poor responders groups. A female preponderance was noted in the good responders group.

CONCLUSION

rGH treatment can safely be used in ISS children. Long-term GH treatment will ameliorate the height deficit and almost 40% of patients may reach their target height.

Effect of summer daylight exposure and genetic background on growth in growth hormone-deficient children

The response to growth hormone in humans is dependent on phenotypic, genetic and environmental factors. The present study in children with growth hormone deficiency (GHD) collected worldwide characterised gene–environment interactions on growth response to recombinant human growth hormone (r-hGH). Growth responses in children are linked to latitude, and we found that a correlate of latitude, summer daylight exposure (SDE), was a key environmental factor related to growth response to r-hGH. In turn growth response was determined by an interaction between both SDE and genes known to affect growth response to r-hGH. In addition, analysis of associated networks of gene expression implicated a role for circadian clock pathways and specifically the developmental transcription factor NANOG. This work provides the first observation of gene–environment interactions in children treated with r-hGH.

Prematurity and low birth weight lead to altered bone geometry, strength, and quality in children

PURPOSE

Prematurity and low birth weight are associated with a decrease in bone mass. Aim of the study was to investigate bone geometry, strength, and quality in children born at term small for gestational age (term SGA), premature appropriate for gestational age (prem AGA), and premature SGA (prem SGA).

METHODS

91 patients (46 f, 45 m), mean age 11.28 years, height SDS 0.03 ± 0.21, and BMI SDS -0.31 ± 0.19. 20 were term SGA, 22 prem SGA, and 49 prem AGA. Bone geometry was assessed on the 2nd metacarpal bone, by evaluating the outer and inner diameter, the cortical area, medullary area, metacarpal index, cross-sectional area, and bone strength. Bone quality was evaluated by ultrasound and expressed as amplitude-dependent speed of sound and bone transmission time (BTT).

RESULTS

Term SGA, prem SGA, and prem AGA had values of bone geometry, strength, and quality significantly lower than our reference range (p < 0.05). Findings in the three groups were similar, apart from BTT, which was significantly reduced in prem SGA (p < 0.05). Fat percentage was the main determinant of BTT.

CONCLUSIONS

Children born either prematurely or SGA seem to have smaller and weaker bones. Those born both premature and SGA were the most affected.

Timing of puberty and physical growth in obese children: a longitudinal study in boys and girls

OBJECTIVE

To assess whether puberty and physical growth vary in obese when compared to normal-weight children.

METHODS

One hundred obese pre-pubertal children (44 boys; mean age (±SD): 9.01 ± 0.62 years; 56 girls; 8.70 ± 0.57 years) were compared to 55 normal-weight controls (27 boys; 9.17 ± 0.26 years; 28 girls; 8.71 ± 0.62 years). All study participants were followed prospectively with 6-monthly follow-up visits. At each study visit, height, weight, body mass index (BMI) and pubertal stage were assessed.

RESULTS

Obese children entered puberty and achieved later stages of puberty earlier than controls (onset of puberty: boys: 11.66 ± 1.00 vs. 12.12 ± 0.91 years, P = 0.049; girls: 9.90 ± 0.78 vs. 10.32 ± 1.70, P = 0.016; late puberty: boys: 13.33 ± 0.71 vs. 14.47 ± 1.00 years, P < 0.001; girls: 11.54 ± 0.99 vs. 12.40 ± 1.02, P = 0.001). Pre-pubertal BMI standard deviation score (SDS) was inversely associated with both age at the onset of puberty (β = -0.506, P < 0.001) and age at late puberty (β = -0.514, P < 0.001). Obese children also showed an earlier age at peak height velocity (PHV) (boys: 12.62 ± 0.82 vs. 13.19 ± 0.96 years, P = 0.01; girls: 11.37 ± 0.89 vs. 12.77 ± 0.76, P < 0.001) and a lower PHV (boys: 7.74 ± 1.49 vs. 9.28 ± 1.64 cm year(-1) , P < 0.001; girls: 7.60 ± 1.64 vs. 8.29 ± 1.03, P = 0.03). Height SDS progressively declined over the study period in the obese group (P for trend <0.001), whereas there were no significant changes in the control group (P for trend = 0.5).

CONCLUSIONS

Obese boys and girls presented an earlier onset of puberty and completion of puberty and an impaired height gain during puberty.

Comparison of radiogrammetrical metacarpal indices in children and reference data from the First Zurich Longitudinal Study

BACKGROUND

A number of radiogrammetrical metacarpal indices are in use, some of which have been adapted for children.

OBJECTIVE

The purpose of this study was to compare four known indices-bone mineral density (BMD), relative cortical area, Exton-Smith index, bending breaking resistance index-and the more recently defined pediatric bone index (PBI) according to the two criteria of minimum height dependence and minimum variability in children of equal bone age.

MATERIALS AND METHODS

A total of 3,121 left-hand radiographs from 231 healthy Caucasian children ranging in age from 3 to 19 years old were analysed using BoneXpert®, a programme for automatic analysis of hand radiographs and assessment of bone age.

RESULTS

Dependence on height for chronological age or bone age and the mean relative standard deviation were lowest in the PBI for both genders pooled. The differences in height dependence were statistically significant and are shown to be clinically relevant. Reference data for PBI are presented.

CONCLUSION

PBI may be a better indicator than BMD for bone health in children; however, verification in a clinical group is needed.

Growth hormone: health considerations beyond height gain

The therapeutic benefit of growth hormone (GH) therapy in improving height in short children is widely recognized; however, GH therapy is associated with other metabolic actions that may be of benefit in these children. Beneficial effects of GH on body composition have been documented in several different patient populations as well as improvements in lipid profile. Marked augmentation of bone mineral density also seems evident in many pediatric populations. Some of these benefits may require continued therapy past the acquisition of adult height. With long-term therapy of any kind, the adverse consequences of treatment should also be considered. Fortunately, long-term GH treatment seems to be safe and well-tolerated. This review describes the long-term metabolic effects of GH treatment in the pediatric population and considers how these may benefit children who are treated with GH.

The effect of growth hormone treatment on bone mineral density in prepubertal girls with Turner syndrome: a multicentre prospective clinical trial

BACKGROUND

Patients with Turner syndrome (TS) are treated with GH to increase adult height. Although it is well established that GH promotes longitudinal bone growth, the effects of GH treatment on bone density are less clear.

OBJECTIVE

To determine how GH treatment affects trabecular bone mineral density (BMD) in girls with TS at prepubertal ages in a prospective multicentre study.

PATIENTS AND METHOD

Twenty-two patients with TS in the prepubertal period with a mean age of 9.8 +/- 2.5 (range 3.6-12.8) years were included in the study. All girls with TS underwent measurement of areal BMD using dual-energy X-ray absorptiometry (DXA) to obtain pretreatment anteroposterior (AP) lumbar spine values at L1-L4. Patients received GH (Genotropin) subcutaneously for 1 year at a dose of 0.05 mg/kg/day. Height and weight were measured at 3-monthly intervals. The AP lumbar spine areal BMD was remeasured using the same technique after 1 year of treatment. Lumbar spine BMD Z-scores and volumetric BMD (vBMD) Z-scores were calculated using national standards.

RESULTS

The height SDS of our cases showed a significant increase with GH therapy. The pretreatment lumbar spine (L1-L4) BMD Z-score was -1.2 +/- 1.2 SD and the vBMD Z-score was -0.8 +/- 1.6 SD. There were no significant changes in these values after 1 year of GH treatment. Prepubertal TS girls more than 11 years of age had lower vBMD Z-scores (-1.7 +/- 1.7 SD) than the girls aged less than 11 (-0.1 +/- 1.0 SD) (P < 0.05) at the onset of therapy. No significant changes were observed in these values after 1 year of GH therapy.

CONCLUSIONS

Osteopaenia becomes apparent in prepubertal TS patients as they reach pubertal age. BMD evaluation may be necessary in these prepubertal TS girls at diagnosis. Short-term GH therapy in these TS patients does not have a significant effect on bone density when measured at a site with a predominance of trabecular bone.

The effects of growth hormone treatment on bone mineral density and body composition in girls with turner syndrome

BACKGROUND

Many girls with Turner syndrome (TS) are treated with GH to increase adult height. In addition to promoting longitudinal bone growth, GH has effects on bone and body composition.

OBJECTIVE

The objective was to determine how GH treatment affects bone mineral density (BMD) and body composition in girls with TS.

METHOD

In a cross-sectional study, we compared measures of body composition and BMD by dual energy x-ray absorptiometry, and phalangeal cortical thickness by hand radiography in 28 girls with TS who had never received GH and 39 girls who were treated with GH for at least 1 yr. All girls were participants in a National Institutes of Health (NIH) Clinical Research Center (CRC) protocol between 2001 and 2006.

RESULTS

The two groups were similar in age (12.3 yr, sd 2.9), bone age (11.5 yr, sd 2.6), and weight (42.8 kg, sd 16.6); but the GH-treated group was taller (134 vs. 137 cm, P = 0.001). The average duration of GH treatment was 4.2 (sd 3.2) yr (range 1-14 yr). After adjustment for size and bone age, there were no significant differences in BMD at L1-L4, 1/3 radius or cortical bone thickness measured at the second metacarpal. However, lean body mass percent was higher (P < 0.001), whereas body fat percent was lower (P < 0.001) in the GH-treated group. These effects were independent of estrogen exposure and were still apparent in girls that had finished GH treatment at least 1 yr previously.

CONCLUSIONS

Although GH treatment has little effect on cortical or trabecular BMD in girls with TS, it is associated with increased lean body mass and reduced adiposity.