Stepped-wedge cluster randomised controlled trial to assess the effectiveness of an electronic medication management system to reduce medication errors, adverse drug events and average length of stay at two paediatric hospitals: a study protocol

INTRODUCTION

Medication errors are the most frequent cause of preventable harm in hospitals. Medication management in paediatric patients is particularly complex and consequently potential for harms are greater than in adults. Electronic medication management (eMM) systems are heralded as a highly effective intervention to reduce adverse drug events (ADEs), yet internationally evidence of their effectiveness in paediatric populations is limited. This study will assess the effectiveness of an eMM system to reduce medication errors, ADEs and length of stay (LOS). The study will also investigate system impact on clinical work processes.

METHODS AND ANALYSIS

A stepped-wedge cluster randomised controlled trial (SWCRCT) will measure changes pre-eMM and post-eMM system implementation in prescribing and medication administration error (MAE) rates, potential and actual ADEs, and average LOS. In stage 1, 8 wards within the first paediatric hospital will be randomised to receive the eMM system 1 week apart. In stage 2, the second paediatric hospital will randomise implementation of a modified eMM and outcomes will be assessed. Prescribing errors will be identified through record reviews, and MAEs through direct observation of nurses and record reviews. Actual and potential severity will be assigned. Outcomes will be assessed at the patient-level using mixed models, taking into account correlation of admissions within wards and multiple admissions for the same patient, with adjustment for potential confounders. Interviews and direct observation of clinicians will investigate the effects of the system on workflow. Data from site 1 will be used to develop improvements in the eMM and implemented at site 2, where the SWCRCT design will be repeated (stage 2).

ETHICS AND DISSEMINATION

The research has been approved by the Human Research Ethics Committee of the Sydney Children's Hospitals Network and Macquarie University. Results will be reported through academic journals and seminar and conference presentations.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry (ANZCTR) 370325.

Waist-to-height ratio and cardiometabolic risk factors in adolescence: findings from a prospective birth cohort

OBJECTIVE

To examine the associations between body mass index (BMI) and waist-to-height ratio (WHtR) measured in childhood and adolescence and cardiometabolic risk factors in adolescence.

METHODS

Secondary data analysis of the Avon Longitudinal Study of Parents and Children, a population based cohort. Data from 2858 adolescents aged 15.5 (standard deviation 0.4) years and 2710 of these participants as children aged 7-9 years were used in this analysis. Outcome measures were cardiometabolic risk factors, including triglycerides, low density lipoprotein cholesterol, high density lipoprotein cholesterol, insulin, glucose and blood pressure at 15 years of age.

RESULTS

Both BMI and WHtR measured at ages 7-9 years and at age 15 years were associated with cardiometabolic risk factors in adolescents. A WHtR ≥0.5 at 7-9 years increased the odds by 4.6 [95% confidence interval 2.6 to 8.1] for males and 1.6 [0.7 to 3.9] for females of having three or more cardiometabolic risk factors in adolescence. Cross-sectional analysis indicated that adolescents who had a WHtR ≥0.5, the odds ratio of having three or more cardiometabolic risk factors was 6.8 [4.4 to 10.6] for males and 3.8 [2.3 to 6.3] for females. The WHtR cut-point was highly specific in identifying cardiometabolic risk co-occurrence in male children and adolescents as well as female children (90 to 95%), but had poor sensitivity (17 to 53%). Similar associations were observed when BMI was used to define excess adiposity.

CONCLUSIONS

WHtR is a simple alternative to age and sex adjusted BMI for assessing cardiometabolic risk in adolescents.

The prevalence of increased central adiposity in Australian school children 1985 to 2007

The epidemic of obesity as measured by body mass index (BMI) maybe plateauing. However, studies using skin-fold and waist circumference measurements suggest that BMI may underestimate changes in fatness in children. In this study we examine changes in waist circumference and waist-to-height ratio (WHtR) in Australian children between 1985 and 2007, by undertaking secondary data analysis of three national data sets. The mean waist circumference z-score for boys increased from -0.02 (95% CI -0.05 to 0.01) in 1985, to 0.33 (0.26 to 0.40) in 1995 and 0.41 (0.35 to 0.47) in 2007 and was greater (P<0.001) than the increase in BMI z-score. The increase in mean waist circumference z-score for girls was greater (P<0.001) than boys and increased from -0.02 (0.05 to 0.01) in 1985, to 0.33 (0.26 to 0.41) in 1995 and to 0.57 (0.51 to 0.63) in 2007. The number of children with a WHtR ≥ 0.5 increased from 8.6% in 1985, to 13.6% in 1995 and 18.3% in 2007. Between 1985 and 2007 central adiposity increased at a faster rate than total adiposity, particularly in girls. The secular increase in waist circumference and WHtR is concerning as measures of central adiposity are associated with metabolic and cardiovascular risk.

Treatment of clinical insulin resistance in children: a systematic review

The objective of this study was to evaluate the effectiveness of interventions aimed at improving clinical insulin resistance and/or pre-diabetes in children. This study is a systematic review and meta-analysis. Five electronic databases were searched for randomized controlled trials of at least 2-months' duration. The outcomes were fasting insulin, homeostasis model assessment of insulin resistance (HOMA-IR), body mass index (BMI) and adverse outcomes. Four randomized controlled trials were identified. All compared the effect of 6 months of metformin plus or minus lifestyle intervention with placebo plus or minus lifestyle intervention. After pooling results from three trials, the mean difference after 6 months favoured the intervention with a statistically significant mean decrease in fasting insulin, HOMA-IR and BMI of 9.6 µU mL(-1) (95% confidence interval [CI]: 6.3, 13.0 µU mL(-1) ; I(2) = 76%), 2.7 (95% CI: 1.7, 3.6; I(2) = 74%) and 1.7 kg m(-2) (95% CI: 1.1, 2.3 kg m(-2) ; I(2) = 75) respectively. Mild gastrointestinal symptoms were reported in 19% (2-29%; median and range) of participants taking metformin. Metformin improves markers of insulin sensitivity and reduces BMI in children and adolescents with clinical insulin resistance or pre-diabetes. Stronger evidence from high-quality studies of longer duration and larger sample size are required before clinical conclusions about the optimal treatment protocol in this population can be drawn.

Sex-specific developmental changes in muscle size and bone geometry at the femoral shaft

INTRODUCTION

When expressed as a percentage of the average result in young adults, bone mineral content lags behind bone length before puberty. Even though this observation has led to speculation about bone fragility in children, such relationships could simply be due to scaling effects when measures with different geometrical dimensions are compared.

METHODS

The study population comprised 145 healthy subjects (6-25 years, 94 females). Magnetic resonance imaging and dual-energy X-ray absorptiometry were used to determine femur length, bone mineral content, cortical bone mineral density, cross-sectional bone geometry (bone diameter; cortical thickness; total, cortical and medullary areas; cross-sectional and polar moments of area; bone strength index) and muscle area at the proximal one-third site of the femur. Results were dimensionally scaled by raising two-, three- and four-dimensional variables to the power of 1/2, 1/3 and 1/4, respectively. Sex-differences were also assessed before and after functionally adjusting variables for femur length and weight or muscle size.

RESULTS

In prepubertal children, unscaled results expressed as percentages of adult values were lowest for variables with the highest dimensions (e.g., moments of area<bone mineral content<cross-sectional areas<femur length). However, when dimensionally scaled, results in children represented similar percentages of the respective average adult values, even after functional adjustments. Before puberty, there was no sex-difference in adjusted bone or muscle variables. After puberty, males had greater total and cortical bone area, bone diameter, moments of area, bone strength index and muscle area than women, both in absolute terms as well as adjusted for femur length and weight. The largest sex-difference was found for muscle area. When compared relative to muscle size, young adult women attained greater total and cortical bone area than men.

CONCLUSIONS

Growth in femoral length, diameter, mass and strength appears well coordinated before puberty. Postpubertal females have narrower femora, less bone strength and muscle size than males. However, when muscle size is taken into account, females have a larger femoral bone cross-section and more cortical bone. These sex-differences likely result from a combination of mechanical and hormonal effects occurring during puberty.

Waist-to-height ratio: a simple option for determining excess central adiposity in young people

Waist circumference is recommended as a means of identifying people at risk of morbidity associated with central adiposity. Yet, there are no universally agreed cut-points to determine when a waist circumference is too large in young people. In this study we examined the relation between sex- and age-specific waist circumference cut-points, the waist-to-height ratio (WHtR) cut-point of <0.5 and cardiovascular disease (CVD) risk clustering in 164 young people, mean age 14.9+/-0.2 years (mean+/-s.d.). In total 19 (11.6%) of the sample were identified as having CVD risk clustering. These young people were significantly (P<0.001) heavier and had higher body mass index (BMI) and waist circumference z-scores compared to those without CVD risk clustering. The WHtR cut-point of 0.5 estimated CVD risk clustering to a similar extent to sex- and age-adjusted cut-points for waist circumference and BMI. Young people with excess central adiposity (WHtR> or =0.5) were 11 times (OR 11.4, P<0.001), more likely to have CVD risk clustering compared to those who did not have excess central adiposity. The WHtR has several advantages; it is easy to calculate, does not require sex- and age-specific centiles and as has been previously suggested, it is a simple message, easily understood by clinicians and families, to 'keep your waist circumference to less than half your height'.

Growth and growth hormone therapy of children treated for leukaemia

A total of 37 children (24 male, 13 female) who had been treated for leukaemia with chemotherapy and 24 Gy cranial irradiation, and who were disease free for at least 18 months, were commenced on somatrem at a mean of 7.6 years (range, 4.8-12.1 years) after leukaemia diagnosis because of growth rate below the 25th centile for bone age. Peak GH response to provocation (exercise, arginine, insulin hypoglycaemia) was less than 20 milliunits/litre in 27 children (deficient group) and 20 milliunits/litre or more in 10 children (non-deficient group). The mean height SD decrease from diagnosis of leukaemia to commencement of somatrem was 1.98, 86% of the children decreasing by more than 1 SD. Those who were tall for age at leukaemia diagnosis and females were more severely affected. Mean (+/- SD) height velocity increased on somatrem from 2.7 +/- 1.1 to 6.6 +/- 2.2 cm/year during the first 6 months (n = 25), and to 6.0 +/- 1.7 cm/year during the first 12 months (n = 19). No difference in growth response was seen between the sexes or between the deficient and non-deficient groups. Catch-up growth occurred for the first 6 months only. It is concluded that children with a low growth rate after treatment of leukaemia should be considered for GH therapy irrespective of the results of GH provocative tests.

The re-emerging burden of rickets: a decade of experience from Sydney

AIM

To define the demographics and clinical characteristics of cases presenting with nutritional rickets to paediatric centres in Sydney, Australia.

METHODS

Retrospective descriptive study of 126 cases seen from 1993 to 2003 with a diagnosis of vitamin D deficiency and/or confirmed rickets defined by long bone x ray changes.

RESULTS

A steady increase was seen in the number of cases per year, with a doubling of cases from 2002 to 2003. Median age of presentation was 15.1 months, with 25% presenting at less than 6 months of age. The most common presenting features were hypocalcaemic seizures (33%) and bowed legs (22%). Males presented at a younger age, with a lower weight SDS, and more often with seizures. The caseload was almost exclusively from recently immigrated children or first generation offspring of immigrant parents, with the region of origin predominantly the Indian subcontinent (37%), Africa (33%), and the Middle East (11%). Seventy nine per cent of the cases were born in Australia. Eleven cases (all aged <7 months) presented atypically with hyperphosphataemia.

CONCLUSIONS

This large case series shows that a significant and increasing caseload of vitamin D deficiency remains, even in a developed country with high sunlight hours. Cases mirror recent immigration trends. Since birth or residence in Australia does not appear to be protective, screening of at risk immigrant families should be implemented through public health policies.

Soft drink consumption and excess weight gain in Australian school students: results from the Nepean study

We studied the relation between soft drink/cordial (a sweet, flavoured, concentrated syrup that is mixed with water to taste), fruit juice/drink and milk consumption in mid-childhood, and body mass index (BMI) status in early adolescence in a contemporary Australian cohort. In 1996/7, 268 children (136 males) were recruited from western Sydney at baseline (mean+/-s.d.: 7.7+/-0.6 years), and at follow-up 5 years later (13.0+/-0.2 years). Height and weight were measured at both time periods and overweight and obesity defined using the International Obesity TaskForce criteria. Beverage consumption was calculated from a 3-day food record at baseline. Median carbohydrate intake from soft drink/cordial was 10 g higher (P=0.002) per day in children who were overweight/obese at follow-up compared to those who had an acceptable BMI at both baseline and follow-up. Intakes of soft drink/cordial in mid-childhood, but not fruit juice/fruit drink and milk, were associated with excess weight gain in early adolescence.

Increasing central adiposity: the Nepean longitudinal study of young people aged 7–8 to 12–13 y

BACKGROUND

Estimates of the prevalence of overweight and obesity in young people are typically based on body mass index (BMI). However, BMI may not indicate the level of central adiposity. Waist circumference has therefore been recommended to identify young people at risk of morbidity associated with central adiposity.

OBJECTIVE

To investigate (a) change in total and central adiposity between 7-8 and 12-13 y (b) agreement between classifying young people as overweight or obese based on total adiposity and central adiposity, and (c) risk factors associated with the development of total and central adiposity.

DESIGN

Anthropometric measurements were taken on 342 children in 1996/97 and 5 y later. Risk factors examined included birth weight, physical activity, TV viewing, pubertal status, parental adiposity, diet and socio-economic status.

RESULTS

Between 7-8 and 12-13 y indices of central adiposity increased more than total adiposity; waist circumference z-score increased by (mean+/-s.d.) 0.74+/-0.92 and BMI z-score increased by 0.18+/-0.67. At 12-13 y there was moderate agreement between the two measures of adiposity (weighted kappa=0.64). However, waist circumference identified a greater number of young people as overweight or obese compared to BMI (41.2 vs 29.3%, P<0.001). Adiposity status at 7-8 y, maternal obesity, and pubertal stage were the strongest predictors of BMI status at 12-13 y. Risk factors associated with increased central adiposity were similar.

CONCLUSIONS

Overweight and obesity, as measured by waist circumference, is a bigger problem than is currently assessed by BMI. Targeting known risk factors for total adiposity may be an appropriate strategy for preventing increased central adiposity.

Prevention and treatment of osteoporosis in chronically ill children

Osteoporosis secondary to chronic disease in children has emerged as a major health issue. As the severity of a child's illness increases, so too does the number of factors affecting their bone health. Determinants of bone health in children include level of mobility, exposure to osteotoxic medication, nutritional status, calcium and vitamin D intake, chronic inflammation and pubertal development.

Cyclic bisphosphonate therapy in osteogenesis imperfecta type V

The clinical and radiographic features and management of a young person with recently delineated Osteogenesis Imperfecta Type V is described. A female aged 9 years presented with a history of multiple fractures since 3 years of age and bilateral dislocation of the elbows from infancy. She was commenced on a low dose frequent regimen of cyclic intravenous pamidronate, which resulted in progressive improvement in bone density, reduced fracture frequency and remission of symptoms of osteoporosis.

Features of the metabolic syndrome after childhood craniopharyngioma

Obesity and multiple pituitary hormone deficiency are common complications after surgery for childhood craniopharyngioma. We hypothesized that post craniopharyngioma surgery, children are at high risk for the metabolic syndrome, including insulin resistance due to excess weight gain and GH deficiency. This study characterized body composition (anthropometry and dual energy x-ray absorptiometry) and metabolic outcomes in 15 children (10 males and 5 females; age, 12.2 yr; range, 7.2-18.5 yr) after surgical removal of craniopharyngioma. In 9 subjects, outcomes were compared with those of healthy age-, sex-, body mass index-, and pubertal stage-matched controls. Insulin sensitivity was measured by 40-min iv glucose tolerance test. Seventy-three percent of subjects were overweight or obese. Sixty-six percent had normal growth velocity without GH treatment. Subjects had increased abdominal adiposity (P = 0.008) compared with controls. However, there was no significant difference in total body fat. Subjects had higher fasting triglycerides (P = 0.02) and lower high density lipoprotein cholesterol to total cholesterol ratio (P = 0.015). Insulin sensitivity was equally reduced for subjects and controls (P = 0.86). After craniopharyngioma removal, patients had more features of the metabolic syndrome compared with controls. This could be a result of hypothalamic damage causing obesity and GH deficiency. Further studies exploring predictors of the metabolic syndrome after craniopharyngioma surgery are required.

A comparison of bone geometry and cortical density at the mid-femur between prepuberty and young adulthood using magnetic resonance imaging

In upper extremity bones, a sexual dimorphism exists in the development of periosteal and endocortical bone surfaces during growth. Little is known about developmental patterns of bone geometry at weight-bearing bones like the femur. Using MRI and dual energy X-ray absorptiometry (DXA), this study assessed the differences in mid-femoral total (TA), cortical (CA) and medullary areas (MA), cortical thickness, and cortical density (BMD(compartment)) between prepuberty and young adulthood in 145 healthy subjects (94 females) 6 to 25 years old. Additionally, agreement between mid-femoral total bone volume (TV) measurements by DXA and MRI were investigated. In both sexes, TA, CA, MA, and cortical thickness were significantly larger in adults compared to prepubertal subjects (P < 0.001), and males had greater values than females. This sex difference persisted for TA, CA, and cortical thickness (P < 0.05), but not MA, after adjusting for femur length and weight. Mean (SD) cortical BMD increased from 1.05 (0.07) and 1.09 (0.10) g/cm(3) in prepubertal children to 1.46 (0.14) and 1.42 (0.1) g/cm(3) in young adults, females and males, respectively (P < 0.001). TV measurements by DXA were significantly greater than by MRI (P < 0.001) in young adults. In conclusion, periosteal and endocortical expansion and increasing cortical BMD are the growth processes found at the mid-femur in both sexes. Our findings contrast to that in upper extremity bones, where MA is constant in females during growth. The difference in femoral bone development may be due to higher strains caused by weight bearing and genetic factors. DXA, in contrast to MRI, is inaccurate in the determination of mid-femoral TV measures.

Importance of lean mass in the interpretation of total body densitometry in children and adolescents

OBJECTIVE

Most studies that use total body dual energy x-ray absorptiometry (DEXA) in children rely on areal bone mineral density (BMD=bone mineral content [BMC]/bone area [BA]) and compare the output with age- and sex-specific normative data. Because this approach is prone to size-related misinterpretation, this study focuses on the interrelations among BMC, body size (height), and lean tissue mass (LTM).

STUDY DESIGN

This cross-sectional study presents normative total body LTM data in relation to height and BMC for 459 healthy white subjects (249 female), 3 to 30 years of age. Guidelines for DEXA interpretation in children are provided and illustrated for patients with growth hormone deficiency (n=5) and anorexia nervosa (n=5).

RESULTS

LTM/height tended to be greater in male than in girls. The BMC/LTM ratio was greater in female than in boys (P<.001), even after adjustment for age and height. Sex-specific reference curves were created for LTM/height, the BMC/LTM ratio, BA/height, and BMC/BA.

CONCLUSIONS

We recommend that total body DEXA in children should be interpreted in 4 steps: (1) BMD or BMC/age, (2) height/age, (3) LTM/height, and (4) BMC/LTM ratio for height. This allows differentiation of the origin of a low BMD or BMC/age, for example, short stature and primary, secondary, and mixed bone defects.

Slowing of growth in height and weight on stimulants: a characteristic pattern

OBJECTIVE

The aims of the present study were to describe the growth pattern of children starting stimulant medication and to analyse the changes over time in height, weight and height velocity in a cohort of treated patients.

METHODS

Retrospective review of growth data from files of all newly treated patients with attention-deficit/hyperactivity disorder in one paediatric practice. Forty-four boys and seven girls were treated for 6-42 months with either dexam-phetamine (n = 32) or methylphenidate (n = 19).

RESULTS

During the first 6 months on stimulant medication 44 children (86%) had a height velocity below the age-corrected mean and there was weight loss in 39 (76%). The height and weight standard deviation score (SDS) showed a progressive decline that was statistically significant after 6 and 18 months (P < 0.001, paired t-test). The height velocity was significantly attenuated for the first 30 months (P < 0.01), being lowest during the first 6 months. The mean height deficit during the first 2 years was approximately 1 cm/year. The change in weight SDS was 2.4 times the change in height SDS after 30 months on treatment with a significant correlation (Pearson's correlation coefficient r = 0.88, P < 0.001).

CONCLUSIONS

Stimulant medication is associated with a decrease in height and weight SDS during the first 6-30 months with a characteristic pattern on the growth chart.

Use of bisphosphonate therapy for osteoporosis in childhood and adolescence

Congenital and acquired forms of osteoporosis in childhood and adolescence can result in morbidity from fracture and pain in childhood, and place an individual at significant risk for problems in adult life. A range of therapies exist for the prevention and treatment of osteoporosis, including optimization of daily calcium intake, adequate vitamin D status, weight-bearing exercise, treatment with sex steroids where delayed puberty is a problem and, more recently, use of bisphosphonate therapy. Intravenous pamidronate therapy (a bisphosphonate) has been shown to reduce fractures and improve bone density in children with osteogenesis imperfecta, and might prove to be of benefit in other osteoporotic conditions in childhood. However, a number of issues regarding the optimal use of bisphosphonate therapy in children and adolescents remain to be resolved, including total annual dose and frequency and duration of administration. Bisphosphonate therapy should, therefore, be used only in the context of a well-run clinical programme with specialist knowledge in the management of osteopenic disorders in childhood.

Effect of pamidronate on distraction osteogenesis and fixator-related osteoporosis

We examined the effect on bone mineral density (BMD), bone mineral content (BMC) and mechanical properties of a single 1.0 mg/kg dose of the bisphosphonate pamidronate (Novartis), in a distraction osteogenesis model in immature rabbits. Twenty rabbits underwent a tibial osteotomy. Ten rabbits received pamidronate 1.0 mg/kg via ear vein intra-operatively while 10 received saline infusions only. After a 24 h latency, all underwent distraction of 0.375 mm twice daily for 15 days. The animals were culled at 42 days. After culling, the distracted and non-distracted tibiae were examined by quantitative computer tomography (QCT). The volumetric bone mineral density (vBMD, mg/cm(3)) in the bone proximal and distal to the regenerate in the operated limb was increased by a mean of 11 and 14%, respectively, compared to controls (P<0.05). The vBMD of the regenerate bone was increased by a mean of 8% over controls (NS, P=0.17). The bone mineral content (BMC, mg) was increased by 23% (proximal and distal) (P<0.05) in the bone surrounding the lengthening and there was a 17% trend towards an increase in the regenerate (NS, P=0.3). Four-point bending analysis documented that the load to failure was increased by 32% from 436 to 574 N (P<0.01) in the pamidronate group. The modulus of elasticity was not different between the control and pamidronate groups (P=0.3), and in both groups was only approximately one-third of the intact tibiae (P<0.001). The administration of a single dose of pamidronate can improve the bone mineral density, content and mechanical properties of a bone undergoing distraction osteogenesis.

Measurement of midfemoral shaft geometry: repeatability and accuracy using magnetic resonance imaging and dual-energy X-ray absorptiometry

Although macroscopic geometric architecture is an important determinant of bone strength, there is limited published information relating to the validation of the techniques used in its measurement. This study describes new techniques for assessing geometry at the midfemur using magnetic resonance imaging (MRI) and dual-energy X-ray absorptiometry (DXA) and examines both the repeatability and the accuracy of these and previously described DXA methods. Contiguous transverse MRI (Philips 1.5T) scans of the middle one-third femur were made in 13 subjects, 3 subjects with osteoporosis. Midpoint values for total width (TW), cortical width (CW), total cross-sectional area (TCSA), cortical cross-sectional area (CCSA), and volumes from reconstructed three-dimensional (3D) images (total volume [TV] and cortical volume [CVol]) were derived. Midpoint TW and CW also were determined using DXA (Lunar V3.6, lumbar software) by visual and automated edge detection analysis. Repeatability was assessed on scans made on two occasions and then analyzed twice by two independent observers (blinded), with intra- and interobserver repeatability expressed as the CV (CV +/- SD). Accuracy was examined by comparing MRI and DXA measurements of venison bone (and Perspex phantom for MRI), against "gold standard" measures made by vernier caliper (width), photographic image digitization (area) and water displacement (volume). Agreement between methods was analyzed using mean differences (MD +/- SD%). MRI CVs ranged from 0.5 +/- 0.5% (TV) to 3.1 +/- 3.1% (CW) for intraobserver and 0.55 +/- 0.5% (TV) to 3.6 +/- 3.6% (CW) for interobserver repeatability. DXA results ranged from 1.6 +/- 1.5% (TW) to 4.4 +/- 4.5% (CW) for intraobserver and 3.8 +/- 3.8% (TW) to 8.3 +/- 8.1% (CW) for interobserver variation. MRI accuracy was excellent for TV (3.3 +/- 6.4%), CVol (3.5 +/- 4.0%), TCSA (1.8 +/- 2.6%), and CCSA (1.6 +/- 4.2%) but not TW (4.1 +/- 1.4%) or CW (16.4 +/14.9%). DXA results were TW (6.8 +/- 2.7%) and CW (16.4 +/- 17.0%). MRI measures of geometric parameters of the midfemur are highly accurate and repeatable, even in osteoporosis. Both MRI and DXA techniques have limited value in determining cortical width. MRI may prove valuable in the assessment of surface-specific bone accrual and resorption responses to disease, therapy, and variations in mechanical loading.

Abdominal fat and birth size in healthy prepubertal children

BACKGROUND

Studies examining the foetal origins hypothesis suggest that small birth size may be a marker of foetal adaptations that programme future propensity to adult disease. We explore the hypothesis that birth size may relate to fat distribution in childhood and that fat distribution may be a link between birth size and adult disease.

OBJECTIVE

To investigate the relationship between birth size and abdominal fat, blood pressure, lipids, insulin and insulin:glucose ratio in prepubertal children.

DESIGN

Cross-sectional study, based on a birth cohort of consecutive full-term births.

SUBJECTS

Two hundred and fifty-five (137 females) healthy, 7- and 8-y-old children.

MEASUREMENTS

Body composition and abdominal fat was measured by dual energy X-ray absorptiometry. Lipid, glucose and insulin profiles were measured after an overnight fast and an automated BP monitor was used for blood pressure measurements.

RESULTS

There was a negative association between abdominal fat and birth weight s.d. score across a range of normal birth weights (beta=-0.18; 95% CI=-0.31 to -0.04, P=0.009) and a positive association with weight s.d. score at 7/8 y (beta=0.35; 95% CI=0.24 to 0.46, P<0.001). Children who were born with the lowest weight s.d. score and had the greatest weight s.d. score at 7/8 y had significantly more (P<0.001) abdominal fat, as a percentage of total fat (6.53+/-1.3%) than those who had the highest birth weight s.d. score and the lowest weight s.d. score at 7/8 y (4.14+/-0.5%). Similar results were seen if head circumference, but not ponderal index, was used as an indicator of birth size. Increased abdominal fat was associated with higher total cholesterol:HDL cholesterol, higher triglyceride concentration and increased diastolic blood pressure.

CONCLUSIONS

Birth weight independently predicted abdominal fat. Children with the highest amount of abdominal fat were those who tended to be born lighter and gained weight centiles. Increased abdominal fat was associated with precursor risk factors for ischaemic heart disease.

Ten years' experience of persistent hyperinsulinaemic hypoglycaemia of infancy

OBJECTIVE

To review the presentation, management and outcome of persistent hyperinsulinaemic hypoglycaemia of infancy seen at the Royal Alexandra Hospital for Children over a 10 year period.

METHODOLOGY

A retrospective review of 20 subjects was performed. As well as laboratory data, data were collected on clinical presentation, medical and surgical management and developmental outcome.

RESULTS

Twenty subjects (11 male) were identified with presentation at a median age of 1.5 months (range 0-10 months), with 10 (50%) presenting in the first week of life. Only 20% of patients were large for gestational age. Diagnosis was made on the basis of high glucose requirements and inappropriately high insulin levels at the time of hypoglycaemia. Eight (40%) responded well to diazoxide treatment alone, seven (35%) received diazoxide in combination with other short-term medical therapy initially and five (25%) required pancreatectomy (repeat surgery in three). Those who required surgery had a higher mean birth weight. Infants presenting in the first week of life were less likely to respond to diazoxide. At the time of last review, eight (40%) of those treated medically had ceased all treatment. Two of the five cases requiring pancreatectomy now require insulin treatment. Neurodevelopmental assessment was normal in 11 (55%), mild delay was found in six (30%) and moderate or severe delay was found in three (15%).

CONCLUSIONS

Persistent hyperinsulinaemic hypoglycaemia of infancy remains a major diagnostic and management challenge. Early suspicion and recognition is critical with definitive investigation and medical therapy to avoid hypoglycaemia, with pancreatectomy in medically unresponsive cases. Normal neurodevelopmental outcome was found in only 55% of cases.

Growth hormone treatment in children with chronic renal failure: a meta-analysis of randomized controlled trials

OBJECTIVE

To evaluate the benefits and side effects of recombinant human growth hormone (hGH) treatment in children with chronic renal failure.

METHODS

Two reviewers independently assessed relevant randomized controlled trials for methodologic quality, extracted data, and estimated summary treatment effects by use of a random effects model.

RESULTS

Ten randomized controlled trials involving 481 children were identified. Treatment with hGH (28 IU/m(2)/wk) resulted in a significant increase in height standard deviation score at 1 year (4 trials, weighted mean difference [WMD] = 0.77, 95% CI = 0.51 to 1.04), and a significant increase in height velocity at 6 months (2 trials, WMD = 5.7 cm/y, 95% CI 4.4 to 7.0) and 1 year (2 trials, WMD = 4.1 cm/y, 95% CI 2.6 to 5.6), but there was no further increase in height indexes during the second year of administration. Compared with the 14 IU/m(2)/wk group, there was an increase of 1.4 cm/y (0.6 to 2.2) in height velocity in the group treated with 28 IU/m(2)/wk. The frequency of reported side effects of hGH were similar to that of the control group.

CONCLUSION

On average, 1 year of treatment with 28 IU/m(2)/wk hGH in children with chronic renal failure results in an increase of 4 cm/y in height velocity above that of untreated control subjects, but there was no demonstrable benefit for longer courses or higher doses of treatment.

Intravenous pamidronate reduces osteoporosis and improves formation of the regenerate during distraction osteogenesis. A study in immature rabbits

We examined the effect on bone mineral density (BMD) of a single dose of 3 mg/kg of the bisphosphonate, pamidronate (Novartis) in distraction osteogenesis in immature rabbits. Seventeen rabbits (9 control, 8 given pamidronate) were examined by dual-energy x-ray absorptiometry. There was a significant increase in the BMD in the pamidronate group compared with the control animals. The mean areal BMD (g/cm2) in the bone proximal and distal to the regenerate was increased by 40% and 39%, respectively, compared with the control group (p < 0.05). The BMD of the regenerate bone was increased by a mean of 43% (p < 0.05). There was an increase of 22% in the mean area of regenerate formed in the pamidronate group (p < 0.05). Histological examination of bone in nine rabbits (5 control, 4 pamidronate) showed an increase in osteoblastic rimming and mineralisation of the regenerate, increased formation of bone around the pin sites and an increase in the cortical width of the bone adjacent to the regenerate in the rabbits given pamidronate. Pamidronate had a markedly positive effect. It reduced the disuse osteoporosis normally associated with lengthening using an external fixator and increased the amount and density of the regenerate bone. Further study is required to examine the mechanical properties of the regenerate after the administration of pamidronate.

Intravenous pamidronate reduces osteoporosis and improves formation of the regenerate during distraction osteogenesis

We examined the effect on bone mineral density (BMD) of a single dose of 3 mg/kg of the bisphosphonate, pamidronate (Novartis) in distraction osteogenesis in immature rabbits.

Seventeen rabbits (9 control, 8 given pamidronate) were examined by dual-energy x-ray absorptiometry. There was a significant increase in the BMD in the pamidronate group compared with the control animals. The mean areal BMD (g/cm2) in the bone proximal and distal to the regenerate was increased by 40% and 39%, respectively, compared with the control group (p < 0.05). The BMD of the regenerate bone was increased by a mean of 43% (p < 0.05). There was an increase of 22% in the mean area of regenerate formed in the pamidronate group (p< 0.05).

Histological examination of bone in nine rabbits (5 control, 4 pamidronate) showed an increase in osteoblastic rimming and mineralisation of the regenerate, increased formation of bone around the pin sites and an increase in the cortical width of the bone adjacent to the regenerate in the rabbits given pamidronate.

Pamidronate had a markedly positive effect. It reduced the disuse osteoporosis normally associated with lengthening using an external fixator and increased the amount and density of the regenerate bone. Further study is required to examine the mechanical properties of the regenerate after the administration of pamidronate.

Mutational analysis and genotype-phenotype correlation of the PHEX gene in X-linked hypophosphatemic rickets

PHEX is the gene defective in X-linked hypophosphatemic rickets. In this study, analysis of PHEX revealed mutations in 22 hypophosphatemic rickets patients, including 16 of 28 patients in whom all 22 PHEX exons were studied. In 13 patients, in whom no PHEX mutation had been previously detected in 17 exons, the remaining 5 PHEX exons were analyzed and mutations found in 6 patients. Twenty different mutations were identified, including 16 mutations predicted to truncate PHEX and 4 missense mutations. Phenotype analysis was performed on 31 hypophosphatemic rickets patients with PHEX mutations, including the 22 patients identified in this study, 9 patients previously identified, and affected family members. No correlation was found between the severity of disease and the type or location of the mutation. However, among patients with a family history of hypophosphatemic rickets, there was a trend toward more severe skeletal disease in patients with truncating mutations. Family members in more recent generations had a milder phenotype. Postpubertal males had a more severe dental phenotype. In conclusion, although identifying mutations in PHEX may have limited prognostic value, genetic testing may be useful for the early identification and treatment of affected individuals. Furthermore, this study suggests that other genes and environmental factors affect the severity of hypophosphatemic rickets.

The effects of growth hormone deficiency and growth hormone replacement therapy on bone. A meeting report

Recently, several reports have described the effects of growth hormone (GH) deficiency (GHD) on bone and the associated potential benefits of GH therapy. Not all of these reports have, however, been consistent and the results are debated. Some of the contention surrounding this issue reflects disagreement about which bone parameters are the best indicators of bone strength and fracture risk. In November 1999, a meeting was held in Taormina, Italy, to discuss the assessment of bone in patients with GHD and the effects of GH therapy on the skeleton. The participants included endocrinologists, orthopaedists and biophysicists from around the world. During the meeting, the advantages and disadvantages of the various indicators of bone strength were defined. In considering GH therapy, the delegates agreed that it had beneficial effects on bone in adults with GHD, but that further studies were needed in GH-deficient children. Finally, the participants stressed the need for more data to clarify which indicator of bone strength is the most appropriate to use in adults and children with GHD, and to define fully the role of GH therapy in bone metabolism. It was recognized that pharmacoepidemiological surveys, such as KIGS (Pharmacia International Growth Database) and KIMS (Pharmacia International Metabolic Database), are valuable sources of such data, and are, therefore, important in the development of evidence-based medicine.

Bone markers and bone mineral density during growth hormone treatment in children with growth hormone deficiency

Growth hormone (GH) has a positive impact on muscle mass, growth and bone formation. It is known to interact with the bone-forming unit, with well-documented increases in markers of bone formation and bone resorption within weeks of the start of GH therapy. These changes relate significantly to short-term growth rate, but it is not evident that they predict long-term response to GH therapy. The consequences of GH deficiency (GHD) and GH replacement therapy on bone mineral density (BMD) have been difficult to interpret in children because of the dependency of areal BMD on height and weight. Some studies have tried to overcome this problem by calculating volumetric BMD, but results are conflicting. The attainment of a normal peak bone mass in an individual is considered important for the future prevention of osteoporosis. From the limited data available, it appears difficult to normalize bone mass totally in GH-deficient individuals, despite GH treatment for long periods. Studies to date examining the interaction between GH and bone have included only small numbers of individuals, making it difficult to interpret the study findings. It is hoped that these issues can be clarified in future research by the direct measurement of bone density (using quantitative computer tomography). Mineralization is only one facet of bone strength, however; other important components (e.g. bone structure and geometry) should be addressed in future paediatric studies. Future studies could also address the importance of the degree of GHD in childhood; how GH dose and insulin-like growth factor-I levels achieved during therapy relate to the final outcome; whether or not the continuation of GH therapy after the attainment of final height may further enhance bone mass; whether the timing and dose of other treatments (e.g. sex hormone replacement therapy) are critical to the outcome; and whether GHD in childhood is associated with an increased risk of fracture.

Safety issues in children and adolescents during growth hormone therapy--a review

The action of growth hormone (GH) via its receptor involves many organ systems and metabolic pathways. These diverse actions are reviewed in this paper in the context that they may represent unwanted side-effects of GH therapy for growth promotion. The monitoring of GH therapy in large multicentre international databases has demonstrated a low frequency of adverse events. Tumour recurrence or new malignancy are not increased. Headaches, especially in the first few months of therapy, require close evaluation as benign intracranial hypertension is found infrequently, especially in children with GH deficiency and chronic renal failure (CRF). Children at risk for slipped capital femoral epiphysis and scoliosis require close monitoring during therapy. Decreased insulin sensitivity that is dose-dependent is observed during GH therapy. Glucose homeostasis, however, is not affected, but a recent report of increased incidence of Type 2 diabetes mellitus in children undergoing GH therapy requires prospective surveillance.

Effects of gender, body composition and birth size on IGF-I in 7- and 8-year-old children

We investigated the relationship between IGF-I, gender, height, weight, body composition and birth size in 260 healthy 7- and 8-year-old children (139 females). All children were born term at Nepean Hospital, Western Sydney. Body composition was measured using dual energy X-ray absorptiometry. IGF-I levels were determined by radioimmunoassay. Girls had higher IGF-I levels than boys (20.2 +/- 6.5 nmol/l compared to 15.9 +/- 6.1 nmol/l, p < 0.001) but there was no correlation between age and IGF-I. IGF-I was positively correlated with height SDS (R(2) = 0.12), weight SDS (R(2) = 0.19), BMI SDS (R(2) = 0.18), total body fat (%) (R(2) = 0.14), and fat-free tissue/cm (R(2) = 0.03). After adjusting for gender and current weight, IGF-I-levels were inversely related to birth size - children with the lowest birth size and heaviest current weight had the highest IGF-I levels. This correlation between birth weight and IGF-I supports the hypothesis that the IGF-I axis is altered in babies who are small for gestational age.

Effects of delaying puberty on bone mineralization in female rats

The effect of delaying puberty on bone mineralization was studied using female rats as a model. Repeated injections of gonadotrophin-releasing hormone antagonist (GnRHa) were used to suppress the onset of puberty from the age of 6-10 weeks. A group of control female rats was given aqueous solution injections at the same age and for the same duration. The effect of delaying puberty on bone mineralization was examined using dual energy X-ray absorptiometry (DXA) and peripheral quantitative computerized tomography (QCT), both methods being adapted for small animals. Bone mineral parameters were measured at baseline and at the ages of 10, 17 and 24 weeks in total body, femur and spine. Compared to controls, bone mineral content (BMC) and bone mineral density (BMD), as measured by DXA, were significantly decreased in GnRHa-treated rats in total body and femur at 10 and 24 weeks of age (P < 0.05). The results were even more significant after adjusting for weight. After this adjustment, spine BMC and BMD at 10, 17 and 24 weeks were significantly lower in the treatment group (P < 0.05). Trabecular BMD at the distal femur in the GnRHa treated group as measured by peripheral QCT was significantly lower (P < 0.05). However, cortical bone in the mid-femur had higher BMD, concurrent with lower cortical thickness in the treatment group. In conclusion, a delay in the onset of sexual maturation may cause prolonged, possibly irreversible defect in bone mineralization.

Growth and endocrine function in children with acute myeloid leukaemia after bone marrow transplantation using busulfan/cyclophosphamide

Longitudinal studies of growth and endocrine function of children with AML transplanted with BUCY are limited. We report a cohort of 23 children with AML transplanted (15 autologous and eight allogeneic) following a single chemotherapy protocol and surviving at least 2 years after BMT. Busulfan was given as a single daily dose. Growth and endocrine function was evaluated yearly from one up to 10 years post transplant (median 4.9 years). The mean height standard deviation score (HtSDS) of the entire group decreased from 0.01 (s.e.m. +/- 0.25) at diagnosis to -0.38 (+/- 0.28) at BMT (P = 0.001). There was no statistically significant difference between HtSDS at BMT and yearly HtSDS from 1 to 5 years post BMT. There was no significant relationship between age at BMT and subsequent change in HtSDS. To date, five of six girls have needed sex steroid replacement. Six of 12 evaluable boys had abnormal gonadotrophins, but none required sex steroid replacement. Children with AML who undergo BMT with BUCY show no significant growth impairment, but gonadal dysfunction is prominent, particularly in girls. Bone Marrow Transplantation (2000).

Initial characterization of the GH-IGF axis and nutritional status of the Ati Negritos of the Philippines

BACKGROUND AND OBJECTIVE

The Ati Negritos are a Pygmy-like aboriginal population from the Philippines with physical characteristics of short stature, dark skin and woolly, kinked hair. Their final height, components of their GH-IGF axis and various nutritional markers are described. SUBJECTS, DESIGN AND MEASUREMENTS: Auxological data and sera for the components of the GH-IGF axis and nutritional parameters were collected from 9 adult Ati Negritos in their native environment and 10 Filipinos in Sydney.

RESULTS

The height SDS (- 3.66 +/- 1.1 vs. - 1.01 +/- 1.2), weight SDS (- 2.30 +/- 1.6 vs. 0.10 +/- 0.7), and BMI SDS (- 1.4 +/- 1.8 vs. - 0.2 +/- 0.5) between the two groups were significantly different (P < 0.01). The mean height of the 6 male Ati Negritos was 149 +/- 7 and 144 +/- 3 cm for the females and are comparable with the African Pygmies and the Mountain Ok people of Papua New Guinea. The Ati Negritos showed lower growth hormone binding protein (GHBP), insulin-like growth factor I (IGF-I), insulin-like growth factor binding protein 3 (IGFBP-3), acid labile subunit (ALS), zinc, albumin, ferritin, iron, iron saturation and much higher insulin-like growth factor binding protein 2 (IGFBP-2) and plasma transferrin concentrations. No differences were noted in random growth hormone (GH), plasma insulin-like growth factor II (IGF-II), nor in their plasma concentrations of prealbumin, thyroid stimulating hormone (TSH) and free thyroxine (T4).

CONCLUSION

Perturbations of both the GH-IGF-I axis and nutritional markers exist in the Ati Negritos. These findings may be determinants of their stature; however, the aetiology of these changes remains to be fully elucidated.

Nutrition in early life: somatic growth and serum lipids

This paper addresses the questions of whether early nutritional experience affects later somatic growth, the growth of the adipose tissue, or the levels of serum lipids among well-nourished children. The analyses are based on data from three prospective studies. Postnatal nutrition and growth: there were differences in growth between breast-fed and formula-fed children. There was no association between linear growth and differences in food energy or macronutrient intake. Birth size and postnatal growth: there was no association between ponderal index (PI) at birth and body mass index (BMI) in the second year. For boys, the PI at 3 and 6 months of age was significantly positively correlated with BMI at the ages of 8 and 15 years, but not for girls. Childhood growth and lipids: there was no association between lipids at the age of 8 years and either birth weight or length, but children who had had a low PI at birth had higher lipid levels at the age 8 years. A positive association was found between serum lipids and abdominal fat and BMI. We conclude that, although early diet may influence growth rate beyond infancy, the evidence for fat patterning resulting from differences in fetal or early postnatal nutrition is still open to question.

Vitamin D receptor alleles predict growth and bone density in girls

OBJECTIVES

Polymorphism of the vitamin D receptor (VDR), collagen alpha I type I (Col I alpha I), and oestrogen receptor (ER) genes have been shown to account for some of the heritability of bone mineral density (BMD) in adults. This study examined this relation in prepubertal children.

METHODS AND SUBJECTS

The relation between genotypes of VDR gene (Taq I, Bsm I, Fok I), Col I alpha I gene (Msc I), and ER gene (Pvu II) with areal BMD, volumetric BMD, and growth were examined in 114 (68 girls) healthy 7 year old, white children.

RESULTS

The genotype of the VDR gene (Taq I) correlated with lumbar spine (L1-4) volumetric BMD in girls only, but at no other bone sites. In girls, VDR genotype affected areal BMD at all sites. After adjusting for height and weight, however, this effect was explained completely by the independent effect of the VDR genotype on growth. Girls with genotype TT, were 3.9 kg heavier and 4.1 cm taller than those with tt, but this relation was not present at birth. No relation was found between genotypes of the VDR gene (Fok I), Col I alpha I gene (Msc I), or ER gene (Pvu II) and BMD or growth variables.

CONCLUSIONS

In prepubertal girls, VDR alleles contribute to lumbar spine volumetric BMD variance, but the areal BMD effect reflects the relation between areal BMD and growth. VDR alleles might affect postnatal growth regulation.

Fat distribution in children and adolescents--the influence of sex and hormones

A significant proportion of the morbidity related to obesity is now recognized to be related to the regional distribution of fat. The advent of dual energy X-ray absorptiometry has facilitated the assessment of body composition in a number of investigations on body fat. From current data, including the authors' own study of trunk and leg fat in 335 children and young adults, it is evident that gender differences for total body fat, percentage of body fat and distribution of fat occur after the pubertal years. Males develop a distribution of fat which favours central deposition of fat irrespective of their total body fat--a distribution that is, unfortunately, associated with a number of adverse implications on health. Furthermore, this tendency to increasing abdominal fat is independent of adipose tissue mass. Hormonal regulators of adipose tissue, including growth hormone which is already known to increase free fatty acids and decrease fat cell mass, need to be studied to account for these gender differences.

Growth hormone therapy in Silver Russell syndrome: 5 years experience of the Australian and New Zealand Growth database (OZGROW)

Data were analysed on 33 children (22 males) with Silver Russell syndrome treated with growth hormone for periods up to 5 years. Baseline data (medians) at commencement of growth hormone (GH) therapy were age 6.7 years, bone age delay 1.7 years, height standard deviation score (SDS)-3.2, weight SDS -3.1, and growth velocity 5.7 cm/ year. All were prepubertal. Median birth weight SDS for gestational age was -3.2. GH was commenced at 14 IU/m2 per week and subsequently adjusted according to response. Growth velocity and growth velocity SDS for chronological age (CA) improved over baseline and gains in height SDS for CA were 1.0, 1.5 and 1.8 SD over 3, 4 and 5 years respectively (P < 0.001). No significant increase in height SDS for bone age was observed. Increased GH doses were required after the 1st year to maintain growth rates. Mean bone age advancement was 3.1 years after 3 years of treatment, and 6.0 years after 5 years treatment. Younger age was a predictor of the growth response over the 1st year. Predictors of response after 3 years were catch up growth, low weight SDS at birth and low height SDS for CA. Age at onset of puberty was normal, but height at onset of puberty was lower than normal means.

CONCLUSION

We have demonstrated significant improvement in growth in Silver Russell syndrome after 3 years of GH therapy, however data on estimated mature height and final height are insufficient to conclude final outcomes. Further follow up is required to assess the long-term benefit.

Volumetric bone mineral density in normal subjects, aged 5-27 years

Concerns have been raised regarding the validity of using areal bone mineral density (aBMD) as a substitute for the true volumetric bone mineral density (vBMD) in the pediatric population. We studied 209 normal subjects (109 males), aged 5-27 yr, to examine the influence of age, gender and growth on vBMD. The femoral neck, midthird of the femoral shaft, and the four lumbar vertebral bodies (L1-L4) were studied. Using data on bone width and height obtained by dual energy x-ray absorptiometry, bone volume was calculated with the assumption that all three sites are cylinders. In contrast to aBMD, vBMD of the femoral neck bore no relationship to age or weight in both sexes, but was significantly related to height in females (r2 = 0.07; P = 0.01). Similarly, vBMD of the femoral shaft (vFBMD) did not change with age or height in either sex. In females, a significant inverse relationship was seen between vFBMD and weight (r2 = 0.14; P = 0.001). Male subjects had higher vFBMD than females (mean +/- SD, 0.73 +/- 0.11 vs. 0.70 +/- 0.12; P = 0.047), but no sex difference was seen in vBMD of the femoral neck. Conversely, vBMD of L1-L4 remained age and growth dependent, although the strength of the relationship was weaker than that for aBMD (data not shown). In conclusion, the vBMD of the femoral neck and shaft is independent of age and is less dependent on growth variables in children and young adults than is aBMD. These observations offer a different perspective from our previous concepts of aBMD.

Growth hormone therapy for 3 years: the OZGROW experience

OBJECTIVE

To examine the growth response over 3 years of growth hormone deficient (GHD) and non-GHD children who have received growth hormone (GH) in Australia.

METHODOLOGY

A retrospective study of a group of patients (1362 children) who commenced GH prior to 1 September 1990. Data were collected at 12 growth centres located in major cities throughout Australia. The data were transferred after informed consent to the national OZGROW database located at the Royal Alexandra Hospital for Children, Sydney, NSW. Of the 1362 children, 898 had received 3 years or more GH therapy and were eligible for this analysis. This cohort was then categorized by diagnosis. Growth response was assessed using height standard deviation score, estimated mature height, growth velocity (GV), GH dose and bone age (years).

RESULTS

For children who completed 3 years therapy, the baseline characteristics among diagnostic groups were similar with mean height standard deviation score (SDS) less than -3 SDS (except for the malignancy group) and mean GV ranging from 3.5 to 4.4cm/year. The GV during the first year improved in all groups (7.7-9.4cm/year)followed by an attenuated response during the second and third years of therapy. After 3 years GH therapy the GHD group with peak levels <10 mU/L demonstrated the greatest change in estimated mature height and height SDS. The GHD group with peak levels between > or = 10 but <2OmU/L had a growth response similar to the non-GHD children for all outcome parameters. Change in bone age ranged from 3.1 to 3.8 years with no differences being noted between the diagnostic groups, nor consistently with pubertal status.

CONCLUSIONS

Australian GH guidelines have targeted very short children when compared to other series. This large cohort of non-GHD children has demonstrated short-term benefits of GH therapy; however, the long-term benefit remains unclear until these children reach final adult height.

Overnight growth hormone secretion in achondroplasia: deconvolution analysis, correlation with sleep state, and changes after treatment of obstructive sleep apnea

The normal profile for overnight GH secretion in achondroplasia has not been previously studied. Factors that have been shown to influence GH secretion include age, obesity, sleep state, and the presence of obstructive sleep apnea (OSA). We assessed GH levels in a group of subjects with achondroplasia, during overnight polysomnography. Nineteen subjects with achondroplasia were studied at 11.3 y of age (median 6.7, range 1.8-30.9). Levels of GH were measured using time-resolved immunofluorometric assay (DELFIA, Pharmacia Biotech Inc.) and analyzed by a deconvolution method. Five subjects were restudied after treatment for OSA. Secretion rates of GH were greater in slow wave (SWS) and rapid eye movement (REM) sleep than in stage one and two (SI-II = light non-REM) sleep (p < 0.01). Total overnight GH secretion decreased with increasing age (r2 = 0.22 p < 0.04). Neither the frequency of arousals, frequency of sleep state transitions nor the severity of OSA correlated with measures of GH secretion. Levels of IGF-I correlated independently with age, body weight (percent ideal), and GH secretion rate (r2 = 0.76, p < 0.001). In a group of five subjects treated for OSA, improved respiratory distress index and reduced sleep state transitions were not associated with significant changes in GH secretion rate by sleep stage; SWS [from 0.62 +/- 0.28 mIU/L/min to 1.02 +/- 0.25 mIU/L/min (NS)] and SI-II sleep [from 0.26 +/- 0.07 mIU/L/min to 0.60 +/- 0.16 mIU/L/min (NS)]. However, in those five subjects, a GH secretion peak during the first 2 h of SWS was initially absent, appearing only after treatment of OSA (1.09 +/- 0.38 mIU/L/min) compared with (2.40 +/- 0.59 mIU/L/min (p = 0.01). A profile of overnight GH secretion is presented for subjects with achondroplasia.

Adverse events during growth hormone therapy

The aim of this study was to ascertain the frequency of adverse events occuring during GH therapy in Australia and New Zealand since 1988. Data for children receiving GH has been collected prospectively on a national database, OZGROW, after informed consent has been given. Adverse events were coded by clinicians and have been analysed in relation to the nature of the event and the underlying diagnosis. There were 2922 subjects analysed, representing 9004 years of GH therapy. 151 subjects reported a total of 210 adverse events giving an overall frequency of 2.3% adverse events/patient treated year. Events that were probably related to GH therapy included peripheral oedema, injection site problems and increased frequency of kyphoscoliosis and slipped epiphysis in some groups. Adverse events were more frequent in growth hormone deficient children who had previously been treated for leukaemia, 8.1%, and in children previously treated for craniopharyngioma, 5.6%. A lower frequency was found for those with a diagnosis of idiopathic short stature, 1.6%, and familial short stature, 0.9%. Kyphoscoliosis was more frequently seen in Turner's syndrome, and slipped epiphyses in adolescent individuals with growth hormone deficiency, especially following treatment for leukaemia. There were no de novo tumours reported but the frequencies of recurrence/patient year for leukaemia, solid cranial tumours and craniopharyngioma were 1.1%, 2.2% and 3.8% respectively. A low frequency of adverse events has been reported on the OZGROW database but subsets of patients may be at increased risk of musculoskeletal abnormalities during GH therapy. The frequency of tumour recurrence during therapy is not different from known rates of recurrence in individuals not treated with GH.

Volumetric bone mineral density--a potential role in paediatrics

The use of areal bone mineral density (aBMD) in paediatric populations has aroused some concern, as it fails to take the age-related increase in bone thickness into account. We have developed a measure of true bone density, volumetric bone mineral density (vBMD), which is independent of age and height. In order to examine the relationship between growth parameters, aBMD and vBMD, we studied patients with phenylketonuria (PKU, n = 40), chronic renal failure (CRF, n = 27) and chronic asthma (n = 19). aBMD of the femoral neck and the mid-femoral shaft was measured using dual energy X-ray absorptiometry (DXA), vBMD was calculated on the basis of values of bone mineral content and bone dimension provided by DXA, with the assumption that both sites are cylinders. aBMD and vBMD were then compared with the normal reference, expressed as a standard deviation score (SDS). aBMD and vBMD were normal in the femoral neck region of the PKU group, but aBMD, either standardized for age or for height, was low in the femoral shaft region (p < 0.01). In the CRF group, profound growth retardation was seen (mean height SDS, -3.2) and aBMD and vBMD were both low in the femoral shaft region but not in the femoral neck. In the asthma group, aBMD for age was low at both sites, but vBMD did not differ from that seen in normal individuals. We conclude that the true vBMD provides a different interpretation of bone density compared with aBMD and requires further evaluation in paediatrics because of its age and height independence.

Body-composition assessment by dual-energy x-ray absorptiometry in subjects aged 4-26 y

This cross-sectional study describes the body composition of 265 normal subjects (137 males and 128 females) aged 4-26 y determined by dual-energy x-ray absorptiometry (DXA). Lean tissue mass (LTM) and bone mineral content (BMC) increased with age in females until 13.4 and 15.7 y, respectively, and in males until 16.6 and 17.4 y, respectively. A strong relation between LTM and BMC was found for each sex (r = 0.98, P = 0.0001 for males; r = 0.98, P = 0.0001 for females). DXA percent body fat (%BFDXA) increased with age in females (r = 0.52, P < 0.001) but not in males and was higher in females than in males at all ages. Trunk to leg fat ratio (TLFR) was calculated as DXA trunk fat/leg fat. In post-pubertal age the TLFR was higher in males than in females (1.01 +/- 0.23 and 0.75 +/- 0.16, P = 0.001), but there was no sex difference in younger children. DXA weight underestimated scale weight by a mean of 0.83 kg. %BFDXA correlated with %BF by skinfold thickness measurement with good agreement for males but overestimated %BF by skinfold thickness for females. These normative data for body composition demonstrate significant sex differences in all body compartments after the pubertal years.

'Exaggerated adrenarche' in children presenting with premature adrenarche

OBJECTIVE

Previous reports of endocrinological profiles in children presenting with premature adrenarche have not shown consistent abnormalities. We therefore aimed to review the clinical and biochemical aspects of a large number of patients presenting with premature adrenarche without virilization and determine the relation between clinical and biochemical characteristics and the frequency of adrenal steroid disorders.

DESIGN AND PATIENTS

Eighty-eight patients presenting with adrenarche without virilization during 1985-1992 were retrospectively reviewed. There were 72 girls and 16 boys. All were normotensive and had either prepubertal breasts or testes < 4 ml. In patients with high adrenal androgen levels, adrenal tumours had been excluded by either adrenal ultrasound or CT scan.

MEASUREMENT

We recorded clinical manifestations, auxological data, bone age, biochemical results including basal 17OH-progesterone (b17OHP), dehydroepiandrosterone sulphate (DHEAS), androstenedione (delta 4A), testosterone, cortisol and stimulated 17OHP and cortisol. ACTH stimulation tests (using soluble Synacthen 250 micrograms intramuscularly and collecting blood at 0, 30 and 60 minutes) were performed when clinically indicated. 17OH-Pregnenolone (17OHPreg) was also measured during ACTH stimulation tests in 13 individuals to look for abnormalities of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD).

RESULTS

The age of onset ranged from 3 to 9.5 years (mean 6.8 +/- 1.3). There were no significant differences by sex for height SDS, weight SDS or % ideal body weight, but bone age advancement was greater in males (P < 0.02). The most common presenting clinical manifestation was premature appearance of pubic hair in 93.8%, the other 6.2% presenting with body odour, acne and/or hirsutism. Twelve patients had b17OHP > 6 nmol/l of whom 5 were diagnosed as having congenital adrenal hyperplasia (CAH) resulting from 21-hydroxylase deficiency after ACTH stimulation tests. A further 33 patients who had b17OHP < 6 nmol/l had normal 17OHP and cortisol responses to ACTH stimulation. Patients, after excluding those with CAH, were divided on the basis of their DHEAS levels into prepubertal (< 1.5 mumol/l), pubertal (1.5-6 mumol/l) and above pubertal range (> 6 mumol/l). The 8 patients with DHEAS values above the pubertal range were described as having 'exaggerated adrenarche'. There were no significant clinical differences between these 3 groups, but significant differences were found for bone age advancement and the steroids, b17OHP, delta 4A and testosterone. There was a strong correlation between DHEAS and delta 4A (r = 0.623, P < 0.001). The 'exaggerated adrenarche' group had higher 17 OHPreg/17OHP ratios at 60 minutes after stimulation but these were not diagnostic for 3 beta-HSD deficiency.

CONCLUSION

The value of assessing basal steroids in children presenting with premature adrenarche is demonstrated in this series with 5.7% being diagnosed with 21-hydroxylase deficiency and 9.1% with 'exaggerated adrenarche'. No relation was found between adrenal steroids and clinical features except for the acceleration of bone age. The relation between 'exaggerated adrenarche' and future ovarian hyperandrogenism needs further evaluation.

Cholestatic jaundice and congenital hypopituitarism

OBJECTIVE

The prevalence of cholestatic jaundice as a presenting feature of congenital hypopituitarism is assessed.

METHODOLOGY

A retrospective case record analysis of the presenting features in all patients diagnosed as having congenital hypopituitarism between 1973-93.

RESULTS

Seven of the 20 patients with congenital hypopituitarism presented with cholestatic jaundice as the major initial manifestation of the disorder. Liver biopsy findings in three revealed intracellular bile pigment accumulation and variable giant cell formation.

CONCLUSION

Cholestatic jaundice was the major manifestation of congenital hypopituitarism in 35% of patients presenting in the neonatal or early infancy period.