Copeptin: Utility in Paediatric Patients with Hyponatraemia

INTRODUCTION

Copeptin concentrations are a useful component of the diagnostic workup of paediatric patients with polyuria and polydipsia, but the value of measuring copeptin in patients with hyponatraemia is less clear.

CASE REPORTS

We report 5 children with hyponatraemia in the context of different underlying pathologies. Copeptin concentrations were elevated in 4 cases (13.7, 14.4, 26.1, and 233 pmol/L; reference range 2.4-8.6 pmol/L), suggesting that non-osmoregulated vasopressin release (syndrome of inappropriate antidiuretic hormone) was the underlying mechanism for low sodium levels. In one of the patients, there was an underlying diagnosis of Schaaf-Yang syndrome (MAGEL2 gene mutation) with a clinical picture suggestive of dysregulated vasopressin production with inappropriately high and then low copeptin release. In one hyponatraemic patient, low copeptin concentrations indicated that non-osmoregulated arginine vasopressin release was not the cause of hyponatraemia and oliguria.

DISCUSSION

Copeptin measurement did not influence management acutely but helped to clarify the mechanism leading to hyponatraemia when the result was available. Relatively high and low copeptin concentrations in association with hypo- and hypernatraemia indicate dysregulated vasopressin production in Schaaf-Yang syndrome.

Adjuvant Rituximab-Exploratory Trial in Young People With Graves Disease

CONTEXT

Remission rates in young people with Graves hyperthyroidism are less than 25% after 2 years of thionamide antithyroid drug (ATD).

OBJECTIVE

We explored whether rituximab (RTX), a B-lymphocyte-depleting agent, would increase remission rates when administered with a short course of ATD.

METHODS

This was an open-label, multicenter, single-arm, phase 2 trial in young people (ages, 12-20 years) with Graves hyperthyroidism. An A'Hern design was used to distinguish an encouraging remission rate (40%) from an unacceptable rate (20%). Participants presenting with Graves hyperthyroidism received 500 mg RTX and 12 months of ATD titrated according to thyroid function. ATDs were stopped after 12 months and primary outcome assessed at 24 months. Participants had relapsed at 24 months if thyrotropin was suppressed and free 3,5,3'-triiodothyronine was raised; they had received ATD between months 12 and 24; or they had thyroid surgery/radioiodine.

RESULTS

A total of 27 participants were recruited and completed the trial with no serious side effects linked to treatment. Daily carbimazole dose at 12 months was less than 5 mg in 21 of 27 participants. Thirteen of 27 participants were in remission at 24 months (48%, 90% one-sided CI, 35%-100%); this exceeded the critical value (9) for the A'Hern design and provided evidence of a promising remission rate. B-lymphocyte count at 28 weeks, expressed as a percentage of baseline, was related to likelihood of remission.

CONCLUSION

Adjuvant RTX, administered with a 12-month course of ATD, may increase the likelihood of remission in young people with Graves hyperthyroidism. A randomized trial of adjuvant RTX in young people with Graves hyperthyroidism is warranted.

The impact of testosterone therapy on quality of life in adolescents with Duchenne muscular dystrophy

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Testosterone therapy for pubertal induction was associated with improvements in QoL.

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Physical changes during puberty played an important role.

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Low self-esteem was also a prevailing theme.

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Parent-reported QoL scores were lower than patient-reports, consistent with other literature.

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Data from this study will provide a useful foundation for future work.

Duchenne muscular dystrophy (DMD) is the most common muscular dystrophy in childhood. It is associated with progressive muscle function decline and premature death. Long-term oral glucocorticoid use slows muscle weakness but is associated with several side effects including delayed puberty. This study assessed the impact of a 2-year incremental intramuscular testosterone regimen on quality of life (QoL) in a cohort of 15 adolescents with DMD. The Pediatric Quality of Life Inventory (PedsQL) Neuromuscular module was used to assess QoL and was completed by parent-child dyads. Semi-structured interviews were carried out to understand patient views on testosterone therapy. QoL scores increased in 10 of the 15 participants during treatment, with a mean total PedsQL score of 74.6 pre-treatment v 80.2 post treatment (p = 0.04). This was supported by comments in the semi-structured interviews. Parent-reported PedsQL scores were lower than their child's post treatment (p = 0.007). Testosterone therapy for pubertal induction was associated with an improvement in QoL and the observed physical changes during puberty played an important role. Low self-esteem was also a prevailing theme. This data supports the inclusion of testosterone therapy for pubertal induction as a Standard of Care.

Genetic Analysis of Pediatric Primary Adrenal Insufficiency of Unknown Etiology: 25 Years' Experience in the UK

CONTEXT

Although primary adrenal insufficiency (PAI) in children and young people is often due to congenital adrenal hyperplasia (CAH) or autoimmunity, other genetic causes occur. The relative prevalence of these conditions is poorly understood.

OBJECTIVE

We investigated genetic causes of PAI in children and young people over a 25 year period.

DESIGN SETTING AND PARTICIPANTS

Unpublished and published data were reviewed for 155 young people in the United Kingdom who underwent genetic analysis for PAI of unknown etiology in three major research centers between 1993 and 2018. We pre-excluded those with CAH, autoimmune, or metabolic causes. We obtained additional data from NR0B1 (DAX-1) clinical testing centers.

INTERVENTION AND OUTCOME MEASUREMENTS

Genetic analysis involved a candidate gene approach (1993 onward) or next generation sequencing (NGS; targeted panels, exomes) (2013-2018).

RESULTS

A genetic diagnosis was reached in 103/155 (66.5%) individuals. In 5 children the adrenal insufficiency resolved and no genetic cause was found. Pathogenic variants occurred in 11 genes: MC2R (adrenocorticotropin receptor; 30/155, 19.4%), NR0B1 (DAX-1; 7.7%), CYP11A1 (7.7%), AAAS (7.1%), NNT (6.5%), MRAP (4.5%), TXNRD2 (4.5%), STAR (3.9%), SAMD9 (3.2%), CDKN1C (1.3%), and NR5A1/steroidogenic factor-1 (SF-1; 0.6%). Additionally, 51 boys had NR0B1 variants identified through clinical testing. Although age at presentation, treatment, ancestral background, and birthweight can provide diagnostic clues, genetic testing was often needed to define the cause.

CONCLUSIONS

PAI in children and young people often has a genetic basis. Establishing the specific etiology can influence management of this lifelong condition. NGS approaches improve the diagnostic yield when many potential candidate genes are involved.

Congenital Hypothyroidism: Space-Time Clustering of Thyroid Dysgenesis Indicates a Role for Environmental Factors in Disease Etiology

Background: The etiology of most cases of congenital hypothyroidism (CHT) due to thyroid dysgenesis (DG) is unknown. If transient environmental factors can impact on thyroid gland development, then clustering of cases in time and/or space may occur, and this would be more likely in thyroid DG than dyshormonogenesis (DHG). Methods: The newborn screening program for CHT in Scotland is linked to a central database that includes case details such as postcode. The etiology of CHT is investigated in many cases of CHT using scintigraphy and/or ultrasonography. We looked for evidence of a change in CHT incidence with year of birth and according to season of the year. We then undertook space-time clustering analysis (using a method based on K-functions, with nearest neighbor thresholds) of CHT in Scotland between 1979 and 2015. We also looked for evidence of overall changes associated with sex and area-based birth density. Results: Of 531 cases with CHT during the study period, 290 cases had been categorized as DG (n = 229) or DHG (n = 61) following more detailed investigation. The incidence of CHT increased with year of birth and was in part linked to changing methodology, but there was no seasonality. There was no evidence of overall space-time clustering (p = 0.06), but there was evidence of clustering in babies with DG (p = 0.007). This picture appeared to be most closely linked to underlying thyroid gland hypoplasia rather than thyroid gland agenesis or ectopia. There was significant space-time clustering for both males and females, but clustering was restricted to lesser birth density areas. There was also evidence of clustering for unknown cases (p < 0.001). Clustering of these cases was restricted to females but was present for cases from both greater and lesser birth density areas. There was no evidence of clustering in cases of DHG. Conclusions: These data suggest that an unidentified environmental factor or factors may be involved in the etiology of thyroid DG in Scotland. The variation in CHT incidence observed internationally may reflect environmental as well as genetic factors.

Quality of Life in Children and Young People With Congenital Adrenal Hyperplasia in the United Kingdom - Nationwide Multicentre Assessment

Introduction: Impaired Quality of Life (QoL) in Congenital Adrenal Hyperplasia (CAH) has been demonstrated in adults, but research in children has yielded variable results. We investigated the impact of CAH on QoL of children and adolescents alongside clinical health outcomes (biometric and biochemical profiles). Method: We collected data from 14 tertiary UK centres to explore current health status of 8-18 year olds with CAH. QoL was assessed by using three different questionnaires; strengths and difficulties questionnaire (SDQ), Paediatric Quality of life (PedsQL) and Self-image profile (SIP), the former two completed by both patients and their parents. Height, weight and blood pressure were converted to age and sex adjusted z-scores. Serum markers included 17OH-progesterone (17OHP), androstenedione (D4), testosterone (T) and 11-ketotestosterone (11KT). Statistical Analysis: Statistical analysis comprised of principal component analysis (PCA) followed by multivariate analysis of variance (MANOVA), and post hoc regression. Results: Of the 107 CAH patients included in the study, median age 12.4 years (IQR 10.0-15.1), 55% were female and 104 completed at least 1 questionnaire. Adequate data for PCA was available from 73/107. Three Principal Components (PCs) with observed eigenvalues > 1 explained 71% of the total variance in the observed variables. PC1 reflected ‘disease control’ comprising 17OHP, D4, T and 11KT. PC2 reflected ‘biometrics’ comprising age, and height and weight z-score. PC3 reflected ‘blood pressure’, comprising systolic and diastolic z-score. PC1 correlated with outcomes in the parent and patient SDQ as well as parent PedsQL. PC2 and PC3 did not correlate with QoL. Regression analysis revealed higher scores (indicating lower QoL) in the SDQ domain of emotional problems and PedsQL domain of emotional health in patients where biomarkers suggested good control or overtreatment. Post hoc regression analysis revealed a rise in Androstenedione of 10nmol/L equated to an improved SDQ emotional problems score of 0.5 points and an improved PedsQL emotional health score of 3 points. Conclusion: The study found an interrelation between QoL and biomarkers of disease control in CAH. There were more emotional problems with higher levels of androgen suppression. Biochemical control within normal ranges did not predict emotional problems. However, unexpectedly, patients with very high levels of androgens were highlighted as reporting fewer problems with their emotional QoL. Further research into QoL in CAH and optimal levels of biochemical control will further understanding.

New Therapeutic Horizons for Graves' Hyperthyroidism

Graves' hyperthyroidism is characterized by the presence of autoantibodies that stimulate the thyroid-stimulating hormone receptor (TSHR), resulting in uncontrolled secretion of excessive thyroid hormone. Conventional treatments, including antithyroid medication, radioiodine, or surgery have remained largely unchanged for the past 70 years and either lack efficacy for many patients, or result in lifelong thyroid hormone replacement therapy, in the case of the latter 2 options. The demand for new therapeutic options, combined with greater insight into basic immunobiology, has led to the emergence of novel approaches to treat Graves' hyperthyroidism. The current therapies under investigation include biologics, small molecules, and peptide immunomodulation. There is a growing focus on TSHR-specific treatment modalities, which carry the advantage of eliciting a specific, targeted approach, with the aim of avoiding disruption of the functioning immune system. These therapies present a new opportunity to supersede the inadequate treatments currently available for some Graves' patients, offering hope of successful restoration of euthyroidism without the need for ongoing therapy. Several of these therapeutic options have the potential to translate into clinical practice in the near future. This review provides a comprehensive summary of the recent advances and various stages of development of the novel therapeutic approaches to treat Graves' hyperthyroidism.

Testosterone Treatment of Pubertal Delay in Duchenne Muscular Dystrophy

BACKGROUND

The outlook for adolescents with Duchenne muscular dystrophy (DMD) has improved greatly as a result of corticosteroid use, but treatment will compromise growth and delay puberty. Whether exogenous testosterone can promote growth, development, and skeletal health is unclear.

METHODS

We collected data retrospectively on growth and pubertal response in 14 adolescents with DMD who were treated with testosterone between 2008 and 2014.

RESULTS

A total of 14 boys were treated at a median age of 14.5 years. Eight have finished treatment after a mean age of 3.1 years and the feedback from families was generally positive. The mean testicular volume pretreatment was 2.4 and 3.9 mL posttreatment. The mean baseline testosterone concentrations were < 1.0 and 5.4 nmol/L postintervention. Median height velocity increased from 0.45 cm/y before treatment to 3.6 cm/y after the treatment. The mean height gain was 14.2 cm.

CONCLUSIONS

A broad range of testosterone preparations was used. Testosterone was generally well-liked, but side effects were experienced by some patients and the pubertal growth increment appears to be compromised. Few subjects had adult endogenous testosterone levels posttreatment. Controlled studies are required to determine the most appropriate treatment regimen and the precise impact of testosterone on key outcomes, such as muscle function and bone integrity. Clinicians will then be better placed to advise families about likely benefits and risks.

X-linked acrogigantism syndrome: clinical profile and therapeutic responses

X-linked acrogigantism (X-LAG) is a new syndrome of pituitary gigantism, caused by microduplications on chromosome Xq26.3, encompassing the gene GPR101, which is highly upregulated in pituitary tumors. We conducted this study to explore the clinical, radiological, and hormonal phenotype and responses to therapy in patients with X-LAG syndrome. The study included 18 patients (13 sporadic) with X-LAG and microduplication of chromosome Xq26.3. All sporadic cases had unique duplications and the inheritance pattern in two families was dominant, with all Xq26.3 duplication carriers being affected. Patients began to grow rapidly as early as 2-3 months of age (median 12 months). At diagnosis (median delay 27 months), patients had a median height and weight standard deviation scores (SDS) of >+3.9 SDS. Apart from the increased overall body size, the children had acromegalic symptoms including acral enlargement and facial coarsening. More than a third of cases had increased appetite. Patients had marked hypersecretion of GH/IGF1 and usually prolactin, due to a pituitary macroadenoma or hyperplasia. Primary neurosurgical control was achieved with extensive anterior pituitary resection, but postoperative hypopituitarism was frequent. Control with somatostatin analogs was not readily achieved despite moderate to high levels of expression of somatostatin receptor subtype-2 in tumor tissue. Postoperative use of adjuvant pegvisomant resulted in control of IGF1 in all five cases where it was employed. X-LAG is a new infant-onset gigantism syndrome that has a severe clinical phenotype leading to challenging disease management.

Bones, stones, moans and groans: hypercalcaemia revisited

Disorders of calcium homeostasis are uncommon but important because of the broad spectrum of potential underlying causes that lie on a spectrum from the benign to the life-threatening. Paediatricians may find them challenging because they do not arise often enough for the investigative approach to be second nature. We report a 4-year-old with acute onset profound hypercalcaemia. We focus on an approach to the clinical problem that is based on the potential organ systems affected, namely the gut, bone and kidney. Key biochemical parameters that may help the paediatric team to reach a diagnosis are discussed, as well as important components of acute management.

Prevention and treatment of vitamin D deficiency

Vitamin D insufficiency and deficiency are widespread in many countries. We review the evidence pertaining to its prevention and treatment. Deficiency may be adequately treated with many different therapeutic regimens of either cholecalciferol or ergocalciferol, owing to the high therapeutic index of both compounds. Nevertheless, the current evidence suggests that regular dosing with oral cholecalciferol (e.g., 60,000 IU weekly) may have slight advantages over other regimens when replenishing vitamin D stores following deficiency. For long-term supplementation, smaller regular doses, such as cholecalciferol 1,000 IU daily, or 10,000 IU weekly, are suitable. Giving reliable and specific advice about appropriate sunlight exposure remains difficult because of differing interindividual skin pigmentation and variable sunlight UVB content at different latitudes, at different times of year, and in different terrestrial environments.

Increasing Incidence, but Lack of Seasonality, of Elevated TSH Levels, on Newborn Screening, in the North of England

Previous studies of congenital hypothyroidism have suggested an increasing incidence and seasonal variation in incidence, which may suggest nongenetic factors involved in aetiology. This study describes the incidence of elevated thyroid stimulating hormone (TSH) values in newborns, a surrogate for congenital hypothyroidism, measured as part of the screening programme for congenital hypothyroidism, over an eleven-year period (1994-2005), and assesses whether seasonal variation exists. All infants born in the Northern Region of England are screened by measuring levels of circulating TSH using a blood spot assay. Data on all 213 cases born from 1994 to 2005 inclusive were available. Annual incidence increased significantly from 37 per 100,000 in 1994 to a peak of 92.8 per 100,000 in 2003. There was no evidence of seasonal variation in incidence. The reasons for the increasing incidence are unclear, but do not appear to involve increasing exposure to seasonally varying factors or changes in measurements methods.

Space-time clustering analyses of type 1 diabetes in children from north-east England: support for an infectious aetiology?

BACKGROUND

The aetiology of type 1 diabetes in children is uncertain. A number of recent studies have suggested an infectious aetiology. It has been postulated that an infectious agent may be involved. Support for this hypothesis may be provided by a finding of space-time clustering. The aims of this study were: (i) to determine whether there was space-time clustering in cases of childhood diabetes from north-east England; and to test for differences in space-time clustering: (ii) due to age at diagnosis; (iii) between the sexes and (iv) between levels of residential population density.

METHODS

We studied incidence of type 1 diabetes diagnosed in children aged 0-14 years and diagnosed during the period 1990-2007. All cases were resident in a defined geographical region of north-east England (Northumberland, Newcastle upon Tyne and North Tyneside). We applied a second-order procedure based on K-functions to test for global clustering. Locations were residential addresses at time of diagnosis. Tests were repeated using nearest neighbour thresholds to allow for variable population density, providing the primary result for each analysis. Differences between sexes and between levels of population density were assessed.

RESULTS

We analysed 457 cases of type 1 diabetes. Overall, there was marginally significant evidence of global space-time clustering (P = 0.089). There was statistically significant clustering amongst pairs of cases that contained at least one female (P = 0.017), but not amongst pairs of cases that contained at least one male (P = 0.190). Furthermore, there was significant clustering amongst pairs of cases that contained at least one from a more densely populated area (P = 0.044), but not amongst pairs of cases that contained at least one from a less densely populated area (P = 0.226).

CONCLUSION

Although the analyses have only found marginally significant evidence of global space-time clustering for cases of type 1 diabetes diagnosed in north-east England, there were two notable findings. First, there was evidence of clustering amongst females and secondly clustering was confined to cases from more densely populated areas. These findings are consistent with a possible aetiological involvement of an infectious agent.

Thirst perception and arginine vasopressin production in a kindred with an activating mutation of the type 2 vasopressin receptor: the pathophysiology of nephrogenic syndrome of inappropriate antidiuresis

BACKGROUND

Activating mutations of the vasopressin receptor gene on the X chromosome cause the nephrogenic syndrome of inappropriate antidiuresis (NSIAD). We describe a male child who presented with persistent hyponatraemia and whose mother was also found to be hyponatraemic. She had learnt to avoid excess fluid consumption because of associated malaise. Both individuals had a subnormal ability to excrete a water load with mother also demonstrating a heightened sense of thirst at low serum osmolalities.

RESULTS

Mother and child were found to have the previously characterised activating mutation (p.Arg137Cys) of the arginine vasopressin receptor type 2 gene (AVPR2), but had measurable levels of AVP when hyponatraemic.

CONCLUSIONS

We conclude that female carriers of activating mutations of the vasopressin receptor are susceptible to hyponatraemia and therefore need to be provided with advice regarding fluid intake. An altered thirst perception may increase susceptibility to hyponatraemia. We confirm that the presence of measurable amounts of AVP in patients with hyponatraemia does not exclude the diagnosis of NSIAD.

Diagnosis and management of polyendocrinopathy syndromes

The autoimmune polyendocrinopathy syndromes are variable in presentation and can be challenging to diagnose and manage. Diagnosis of the type 1 autoimmune polyendocrinopathy syndrome can be difficult at an early age when often only one manifestation is present, and it may take years for others to appear. Increased awareness of polyendocrinopathy syndromes, combined with analysis of specific autoantibodies and molecular genetics, should help earlier diagnosis of these conditions and prevent serious complications. Further definition of susceptibility genes and autoantigens, as well as a better understanding of the pathogenesis, is required to improve the diagnosis and management of these patients.

Discordance for X-linked hypophosphataemic rickets in identical twin girls

BACKGROUND

We report monozygotic twin girls with a family history consistent with X-linked hypophosphataemic rickets (XLH). One twin had a skeletal and biochemical phenotype consistent with XLH, whilst the second twin appeared normal. Complete non-penetrance in XLH has not been previously reported and our aim was to explore potential reasons for this.

METHODS

Serum and urine biochemistry were analysed at regular intervals. Microsatellite analysis was performed to confirm monozygosity and bi-parental inheritance of the X chromosome. The X chromosome inactivation pattern was studied in peripheral blood. Exons of the paternal PHEX and FGF23 genes were sequenced.

RESULTS

Biochemistry was persistently abnormal in the slow-growing twin 1 and normal in twin 2 who has grown normally. Maximal tubular phosphate reabsorption was 0.68 mmol/l in twin 1 and 1.64 mmol/l in twin 2 at 10.8 years of age (normal 1.15-2.58 mmol/l). Microsatellite analysis confirmed monozygosity and the X chromosome inactivation pattern was random. These studies also excluded uniparental isodisomy. The exon sequence of paternal PHEX and FGF23 genes was normal.

CONCLUSIONS

Discordant X inactivation is a well-recognised phenomenon in identical twins, and we suspect that non-random expression of the normal PHEX gene in critical tissues is the most likely explanation for non-penetrance.

The impact of fasting and treatment omission on susceptibility to hypoglycaemia in children and adolescents with GH and cortisol insufficiency

OBJECTIVE

Hypoglycaemia may be a frequent occurrence in young GH deficient patients and so we studied the response to fasting in children and adolescents with GH and/or cortisol deficiency.

METHODS

A total of 20 patients (2-18 years) fasted for 14 h (22.00-12.00 h) on two occasions as part of a randomized cross-over study. Fourteen had pituitary hormone deficiency (PHD) including GH deficiency (GHD). Of the 14 patients, seven were ACTH sufficient (PHDC+) and seven ACTH deficient (PHDC-). Six had primary adrenal failure (PAF). Subjects administered or omitted their normal dose of evening GH and/or morning hydrocortisone. Glucose, insulin, GH, cortisol, ketones and catecholamines were measured at 04.00 h and regularly from 07.00 to 12.00 h. Insulin sensitivity was assessed by HOMA and hypoglycaemia defined as a blood glucose (BG) </= 3.3 mmol/l.

RESULTS

BG was related to age and body mass index on treatment but no subject became hypoglycaemic on or off therapy prior to 07.00 h. Five children (aged 3, 4, 7, 8 and 11 years) were hypoglycaemic between 07.00 and 12.00 h off treatment. There was a positive relationship between GH AUC and minimum BG in patients with PHD on treatment (r(2) = 0.45, P = 0.012) with increased insulin sensitivity off treatment. Increased cortisol levels were seen in PHDC+ patients off GH (P < 0.001). A negative relationship was observed between minimum BG and adrenaline (r(2) = 0.37, P = 0.01), ketone bodies (r(2) = -0.20, P = 0.05) and NEFA (r(2) = -0.35, P = 0.02). Noradrenaline levels were reduced in patients with PHDC-. Low BMI (on treatment) and young age (off treatment) were determinants of low BG levels in a multiple regression model.

CONCLUSIONS

Unrecognized overnight hypoglycaemia in children and adolescents on pituitary hormone replacement is uncommon but BG levels quickly become abnormal when treatment and meals are omitted. The insulin antagonistic actions of GH are important in preventing hypoglycaemia. Patients with PHD have altered sympathetic nerve activity.

Prolonged honeymoon phase in an adolescent with diabetes and thyrotoxicosis provides support for the accelerator hypothesis

A 14-yr-old female presented with diabetes and Graves' disease. Eighteen months later, she was euthyroid on carbimazole, and her haemoglobin A1c (HbA1c) was normal (5.2%) on a small insulin dose (0.3-0.4 units/kg/day). An assessment of her pancreatic beta-cell reserve, determined by comparing HbA1c and insulin dose, suggested that this was greater than other patients with type 1 diabetes in our service 18 months postdiagnosis (n = 185). We suspect that excess thyroid hormone led to an insulin-resistant state and accelerated her presentation with hyperglycaemia. Insulin resistance fell once normal thyroid function was restored and helped to attenuate further beta-cell destruction when beta-cell mass was relatively well preserved.

Milk intake and feeding behavior in the first week of life and its relationship to cord blood ghrelin, leptin, and insulin concentrations

Our aim was to study the feeding behavior of healthy term infants in the first week of life and determine whether this was related to cord blood leptin, ghrelin, and insulin. A total of 100 healthy bottle-fed infants were studied by weighing bottles of milk before and after feeds. Leptin, total ghrelin, and insulin concentrations were measured in cord blood. Mean (SD) birth weight was 3.46 (0.43) kg. Mean milk intake increased from 196.7 (83.0) g on d 1 to 585.0 (128.4) g on d 7. Milk intake over the first 6 d was significantly associated with weight gain to d 7. There was no relationship between cord ghrelin or leptin and milk intake or feed frequency. Cord blood insulin was inversely related to the mean daily number of feeds over the first 6 d (r = -0.21, p < 0.05). Birth weight and milk intake are the major determinants of weight gain in the first week of life in healthy bottle-fed infants. Total cord ghrelin and leptin are not directly related to milk intake or feed frequency in the first week of life. Circulating insulin concentrations may have a role in the initiation of feeding behavior.

The role of the IDDM2 locus in the susceptibility of UK APS1 subjects to type 1 diabetes mellitus

Autoimmune polyendocrinopathy syndrome type 1 (APS1) is characterized by autoimmune destruction of endocrine tissues and chronic mucocutaneous candidiasis. Type 1 diabetes (T1D) affects 12-25% of patients with APS1, and the prediction of whether this complication will affect an individual is not currently possible. However, alleles of a variable number tandem repeat (VNTR) 5' of the insulin gene are known to influence the development of T1D in the general, non-APS1 population. Therefore, we investigated the prevalence of these IDDM2 alleles in British Caucasian patients with APS1. The study employed genotyping of 33 patients with APS1 for the HphI polymorphism that is in tight linkage disequilibrium with the insulin gene VNTR alleles. Thirty-three patients with APS1 were studied, the mean age was 23.5 years and 24% have T1D. Six of eight (75%) APS1 patients with T1D were homozygous for the class I INS VNTR (susceptibility) allele, compared with eight of 25 (32%) of APS1 patients without T1D (P = 0.042). Our data suggest an association between the development of T1D and homozygosity for the T1D susceptibility class IINS VNTR allele in patients with APS1.

Hypercalcaemia in relapsed medulloblastoma 8 years post-diagnosis; evidence to support PTHrP production by medulloblastoma cells

BACKGROUND

A 19-year-old male presented with symptomatic hypercalcaemia as the first manifestation of relapsed metastatic medulloblastoma. Management at the time of the initial presentation 8 years earlier was with surgical excision and craniospinal radiotherapy. His biochemistry at the time of relapse and studies of medulloblastoma cell lines provide an insight into the pathogenesis of his hypercalcaemia.

METHODS

Parathyroid hormone-related protein (PTHrP) was measured by immunoradiometric assay in blood, and in conditioned and control media from three medulloblastoma cell lines following 72 h growth.

RESULTS

The histology at initial presentation (11 years of age) and at the time of relapse (with bone marrow infiltration and widespread bony metastases) demonstrated medulloblastoma. Ionised calcium concentrations at relapse were 2.89 mmol/l and serum PTHrP levels were increased at the same time (2.7 pmol/l; normal range: 0.7-1.8 pmol/l). There was evidence of PTHrP production by one cell line (MHH-MED-8A) while results for both other lines tested were below the limit of detection.

CONCLUSIONS

Relapse 8 years after diagnosis is unusual in medulloblastoma and for this relapse to manifest as hypercalcaemia is also very uncommon. Our investigations suggest that the clinical picture was a reflection of PTHrP production by medulloblastoma cells.

Genetic association studies of the FOXP3 gene in Graves' disease and autoimmune Addison's disease in the United Kingdom population

Regulatory T lymphocytes play a crucial role in modulating potentially self-reactive clones, and dysfunction of this cell type contributes to autoimmune disease. FOXP3 is a critical determinant of CD(4+)CD(25+)T regulatory (T(reg)) cell development and function. The aim of this study was to investigate whether genetic polymorphisms at the FOXP3 locus predispose to autoimmune endocrinopathies. Five single nucleotide polymorphisms (SNPs) and two microsatellite polymorphisms were genotyped in our Caucasian cohorts of 633 unrelated Graves' disease (GD) subjects, 104 autoimmune Addison's disease (AAD) subjects and 528 healthy controls. SNP genotyping was performed by either restriction enzyme digestion or by primer-extension-MALDI-TOF (matrix-assisted laser desorption/ionisation time-of-flight) assay. Microsatellites were analysed using fluorescent PCR. Case-control analysis was performed using chi(2) testing on contingency tables for allele frequency. Haplotype analysis was performed using the UNPHASED package. No evidence for disease association was found with any of the seven polymorphisms in either of the GD or AAD subjects as compared with controls (P = 0.26-0.94). Haplotype analysis found a weak evidence for the association of a minor haplotype with GD; this was not significant when corrected for multiple testing. This study has found no robust evidence that FOXP3 gene polymorphism contributes to the susceptibility to GD or AAD in the UK population.

Macroorchidism in two unrelated prepubertal boys with a normal FSH receptor

BACKGROUND

Macroorchidism in prepuberty is an uncommon condition which we hypothesised might reflect constitutive activation of the FSH receptor (FSHR).

PATIENTS AND METHODS

Patient 1 was found to have macroorchidism (15 ml testicular volume) at the time of orchidopexy when 3.7 years of age. A gonadal biopsy was obtained at the time of surgery. Patient 2 developed macroorchidism (5 ml) when 8.8 years old. Despite a testicular volume >4 ml, morning testosterone levels were unrecordable with no measurable gonadotrophin production in either patient. Patient 2 had prepubertal gonadotrophin levels 3 years later despite a testicular volume that was 8 ml bilaterally. Inhibin B was measured and the FSHR sequenced in both patients.

RESULTS

Inhibin B levels were age and pubertal stage appropriate. Gonadal biopsy (patient 1) demonstrated areas of Sertoli cell hyperplasia. Sequence analysis of all 10 exons of the FSHR was normal. There was significant, presumed gonadotrophin-dependent testosterone production in both boys by 15 years of age.

CONCLUSIONS

The cause of prepubertal macroorchidism in our patients is unclear but the pronounced difference in phenotype suggests that there may be more than one underlying mechanism. This mechanism was not constitutive activation of a mutated FSHR.

Primary hyperaldosteronism with normokalaemia secondary to an adrenal adenoma (Conn's syndrome) in a 12 year-old boy

A 12-1/2 year-old boy presented to the Accident Department following an episode of dizziness and was found to be hypertensive. Investigations revealed primary hyperaldosteronism secondary to an adrenal adenoma (Conn's syndrome). He had normal electrolytes during the period of investigation and potassium concentrations were > or = 4.2 mmol/l on all but one occasion. The hypertension resolved following excision of the adrenal tumour. Normokalaemia with potassium >4.0 mmol/l is very unusual in patients with Conn's syndrome and has not been described in childhood before. Primary hyperaldosteronism needs to be considered in hypertensive children even when potassium concentrations are well within the laboratory reference range.

Thyroid dysfunction after bone marrow transplantation for primary immunodeficiency without the use of total body irradiation in conditioning

Thyroid dysfunction, a common long-term complication following bone marrow transplantation (BMT), is frequently associated with total body irradiation (TBI) given in the pre-BMT conditioning protocol. We report our preliminary observation of the prevalence of thyroid dysfunction in children transplanted for primary immunodeficiency (PID) who were given cytoreductive conditioning with busulphan and cyclophosphamide, but without TBI. We evaluated thyroid-stimulating hormone (TSH) and free thyroxine (fT4) in 83 survivors transplanted between 1987 and 2002. We found nine children (10.8%) with clinical and/or biochemical thyroid dysfunction at 4 months to 4.5 years post-BMT of which three had positive antithyroid microsomal antibodies. Two patients were classified as primary and seven as compensated hypothyroidism (hyperthyrotropinaemia). Four patients with clinical features of hypothyroidism received replacement thyroxine, while five of the seven patients with compensated hypothyroidism remain off thyroxine because we suspect this may be a transient phenomenon. Abnormalities of thyroid function including severe primary hypothyroidism may occur post-BMT in children receiving chemotherapy conditioning without TBI. Thyroid function should be assessed regularly in this group of patients.

Comparison of continuation or cessation of growth hormone (GH) therapy on body composition and metabolic status in adolescents with severe GH deficiency at completion of linear growth

Although GH replacement improves the features of GH deficiency (GHD) in adults, it has yet to be established whether cessation of GH at completion of childhood growth results in adverse consequences for the adolescent with GHD. Effects of continuation or cessation of GH on body composition, insulin sensitivity, and lipid levels were studied in 24 adolescents (13 males, 11 females, aged 17.0 +/- 0.3, yr, mean +/- se, puberty stage 4 or 5) in whom height velocity was less than 2 cm/yr. Provocative testing confirmed severe GHD [peak GH < 9 mU/liter (3 microg/liter)] in all cases and was followed by a lead-in period of 3 months during which the pediatric dose of GH continued unchanged. Baseline investigations were then performed using dual-energy x-ray absorptiometry (body composition), lipid measurements, and assessment of insulin sensitivity by both homeostasis model assessment and a short insulin tolerance test. Twelve patients remained on GH (0.35 U/kg.wk), and 12 patients ceased GH treatment. The groups were followed up in parallel with repeat observations made after 6 and 12 months. No endocrine differences were evident between the groups at baseline. GH cessation resulted in a reduction of serum IGF-I Z score [-1.62 +/- 0.29, baseline vs. -2.52 +/- 0.12, 6 months (P < 0.05) vs. -2.52 +/- 0.10, 12 months (P < 0.01)] but values remained unchanged in those continuing GH replacement. Lean body mass increased by 2.5 +/- 0.5 kg ( approximately 6%) over 12 months in those receiving GH but was unchanged after GH discontinuation. Cessation of GH resulted in increased insulin sensitivity [short insulin tolerance test, 153 +/- 22 micromol/liter.min, baseline vs. 187 +/- 20, 6 months (P < 0.05) vs. 204 +/- 14, 12 months (P = 0.05)], but no significant change was seen during 12 months of GH continuation. Lipid levels remained unaltered in both groups. Continuation of GH at completion of linear growth resulted in ongoing accrual of lean body mass (LBM), whereas skeletal muscle mass remained static after GH cessation in these adolescents with GHD. This divergence of gain in LBM is of potential importance because increases in LBM occur as a feature of healthy late adolescent development. GH is a major mediator of insulin sensitivity, independent of body composition in adolescents. Further studies are required to determine whether discontinuation of GH in the adolescent with severe GHD once linear growth is complete results in long-term irreversible adverse physical and metabolic consequences and to determine conclusively the benefits of continuing GH therapy.

Low cord ghrelin levels in term infants are associated with slow weight gain over the first 3 months of life

Lower ghrelin levels have been related to slower growth in small for gestational age infants, and infants with higher cord leptin levels have been reported to gain weight more slowly from birth to 2 yr. This study investigated whether cord blood ghrelin and leptin levels are related to weight gain up to 12 wk of age. One hundred infants were weighed at birth and at 12 wk, and cord blood was assayed for ghrelin and leptin. The mean (+/-sd) birth weight was 3.458 (0.433) kg (median, 3.390; range, 2.510-4.615 kg). The mean (+/-sd) leptin level was 10.1 (6.7) ng/ml (median, 8.4; range, 1.6-36.7 ng/ml), and that of ghrelin was 760.9 (282.9) pg/ml (median, 770; range, 210-1670 pg/ml). Higher birth weight was associated with slower weight gain. Leptin was correlated with birth weight, but ghrelin was not, and leptin and ghrelin levels were not significantly correlated with one another. With birth weight as a control variable, ghrelin was significantly associated with slow weight gain (chi(2) = 7.20 with 1 df; P < 0.01), although leptin was not (chi(2) = 1.59 with 1 df; P > 0.1). In conclusion, lower cord ghrelin levels are associated with slower weight gain from birth to 3 months of age.

GH and Cortisol Response to Glucagon Administration in Short Children

OBJECTIVE

To establish whether there is a link between GH status and glucose response to glucagon and to identify determinants of maximum GH and cortisol concentrations.

METHODS

95 children referred for assessment of short stature, slow growth or suspected hypothalamo-pituitary dysfunction were assigned to normal, organic GH-deficient or non-organic GH-deficient groups on the basis of history, GH response and MRI findings.

RESULTS

Baseline glucose and glucose nadir were related to age in normal children, but the glucose response to glucagon was not linked to GH status. Peak GH response was positively related to age in prepubertal children and peak cortisol was inversely related to age.

CONCLUSIONS

GH status is not a major determinant of the glucose response to glucagon. There is a relationship between age and the GH/cortisol response in short normal children.

Borjeson-Forssman-Lehmann syndrome and multiple pituitary hormone deficiency

We describe two brothers with Borjeson-Forssman-Lehmann syndrome and the 22A-->T (Lys8X) PHF6 mutation, who presented with the symptoms and signs of multiple pituitary hormone deficiency. Biochemical investigations and radiology confirmed growth hormone (GH), thyroid stimulating hormone (TSH) and adrenocorticotrophic hormone (ACTH) as well as gonadotrophin deficiency. They were also found to have optic nerve hypoplasia. This family suggests that the BFL gene product may play an important role in midline neuro-development including the hypothalamo-pituitary axis.

Mutational analysis of the FOXP3 gene and evidence for genetic heterogeneity in the immunodysregulation, polyendocrinopathy, enteropathy syndrome

The immunodysregulation, polyendocrinopathy, enteropathy syndrome (IPEX), is a rare disorder of immune regulation resulting in multiple autoimmune disorders, which demonstrates X-linked recessive inheritance. The disease gene, FOXP3, was identified in 2001, and several mutations within this gene have since been described in patients with IPEX. We used linkage analysis, mutational screening of the FOXP3 gene, human leukocyte antigen typing, and analysis of X-chromosome inactivation to investigate 2 kindreds (21 subjects in total) with 4 male infants (3 now deceased) and 1 girl affected by IPEX. In 1 family a novel FOXP3 mutation was identified in the proband, with a single base deletion at codon 76 of exon 2, leading to a frameshift, which predicted a truncated protein product (108 residues vs. 431 in wild type). In the second family, the FOXP3 locus was excluded by recombination, and mutational analysis of the gene was negative. The affected girl from this family was shown to have human leukocyte antigen DR2 and DR6 alleles and random X-chromosome inactivation in peripheral blood mononuclear cells. Our analysis has elucidated the molecular basis of IPEX in one family and has, for the first time, provided evidence for an autosomal locus, suggesting genetic heterogeneity in this syndrome.

The effect of cessation of growth hormone (GH) therapy on bone mineral accretion in GH-deficient adolescents at the completion of linear growth

In many countries, treatment of childhood-onset GH deficiency (GHD) with GH ceases when linear growth is complete. Peak bone mass occurs several years after the completion of linear growth. Given that GH has important anabolic actions on bone, discontinuation of GH therapy at the completion of linear growth may have adverse consequences for the attainment of peak bone mass in adolescent GHD patients. In this United Kingdom multicenter study, 24 adolescents (13 males, mean age 17.0 +/- 1.4 yr, SD) with severe GHD were randomized to discontinue or continue GH (0.35 IU/kg x wk) at the completion of linear growth. Whole body bone mineral content (BMC) and lumbar spine bone mineral density were assessed by dual-energy x-ray absorptiometry at baseline and then at 6-month intervals for 1 yr. Markers of bone remodeling (serum bone-specific alkaline phosphatase and urinary deoxypyridinoline) were measured at the same time points. In patients who continued GH (GH+), median BMC increased by 3.8% (interquartile range, 2.6, 5.9, P < 0.001) at 6 months; and by 6.0% (3.7-9.1, P < 0.001) at 12 months. In patients who discontinued GH (GH-) median BMC was unchanged at 6 and 12 months (+1.9%, -0.4-4.2, P = 0.9; and +2.4%, 0.4-4.9, P = 0.5, respectively, median, interquartile range). The differences in median change in BMC between the two groups at 6 and 12 months was marginally significant (P = 0.085 and 0.074, respectively). Mean lumbar spine bone mineral density increased by 4.7 (95% confidence interval, 1.0, 8.2) at 12 months in patients continuing GH (P = 0.01), but the mean change was not statistically significant change in patients who discontinued GH [+2.7% (95% confidence interval, -0.8, +6.2)]. These preliminary data suggest that, in adolescent patients with severe GHD, discontinuation of GH at completion of growth may limit the attainment of peak bone mass in this patient group. This may predispose to clinically significant osteopenia in later adult life.

Successful radioiodine treatment in a 3 year old child with Graves' disease following antithyroid medication induced neutropenia

A 3 year old child with Graves' disease and mitral valve prolapse became neutropenic on carbimazole therapy. She was switched to propylthiouracil but the neutropenia recurred. She was treated with radioiodine but required two doses of 113 MBq and then 198 MBq five months later before becoming hypothyroid. The mitral valve prolapse resolved when she was euthyroid on thyroxine replacement. Antithyroid drugs, surgery, and radioiodine all have a place in the management of the thyrotoxic child.

A novel loss of function mutation in exon 10 of the FSH receptor gene causing hypergonadotrophic hypogonadism: clinical and molecular characteristics

BACKGROUND

Inactivating mutations of the FSH receptor (FSHR) are a rare cause of hypergonadotrophic hypogonadism in women. Only one patient with primary amenorrhoea due to an FSHR gene mutation has been reported outside of Finland, where the prevalence of Ala189Val mutations is particularly high.

METHODS AND RESULTS

Here, we describe the clinical, molecular genetic and functional characteristics associated with a novel inactivating mutation in exon 10 of the FSHR gene identified in a patient who presented with primary amenorrhoea at 17 years of age. The C to G transversion found at nucleotide 1043 causes a Pro348Arg substitution in the extracellular region of the FSHR and results in a mutant FSHR that is completely inactive in functional studies and that does not bind FSH. The proband exhibits apparent homozygosity for this recessive mutation. Her father is heterozygous for the mutation while analysis of exon 10 of the FSHR gene from her mother revealed only wild-type sequence. Chromosome painting was used to exclude deletions or rearrangements of 2p, and microsatellite markers did not show paternal uniparental isodisomy for this region. These findings suggest that the proband is hemizygous, with an inherited or de-novo microdeletion, or alternatively a de-novo gene conversion, of the accompanying FSHR allele.

CONCLUSIONS

This case confirms the importance of the FSHR in female pubertal development and reproduction, and supports a relationship between phenotype and function for FSHR mutations.

Orthotopic liver transplantation for acute liver failure secondary to autoimmune hepatitis in a child with autoimmune polyglandular syndrome type 1

Autoimmune polyglandular syndrome type 1 (APS-1) is an autosomal-recessive condition characterized by hypoparathyroidism, autoimmune Addison's disease, and chronic mucocutaneous candidiasis. Autoimmune hepatitis develops in 10-20% of affected patients and has a variable course ranging from asymptomatic chronic liver disease to lethal fulminant hepatic failure. Liver transplantation has been documented previously in only two patients. We report a 14-yr-old boy with APS-1 who developed acute liver failure secondary to associated autoimmune hepatitis. He did not respond to corticosteroid therapy and was successfully treated with an orthotopic liver transplant.

Multicystic dysplastic kidney and Kallmann's syndrome: a new association?

BACKGROUND

Kallmann's syndrome is characterized by anosmia and hypogonadotrophic hypogonadism. Radiographic studies of teenagers and older subjects with the X-linked form of the syndrome have shown that up to 40% have an absent kidney unilaterally. Although this has been attributed to renal "agenesis", a condition in which the kidney fails to form, little is known about the appearance of the developing urinary tract either pre- or post-natally in individuals with Kallmann's syndrome.

METHODS

We describe two brothers who had features of Kallmann's syndrome, most probably of the X-linked variety, who both had a major urinary-tract malformation detected before birth.

RESULTS

The brothers were found to have unilateral multicystic dysplastic kidneys on routine antenatal ultrasound scanning and both underwent surgical nephrectomy of these organs post-natally. Immunohistochemical studies on the younger sibling revealed hyperproliferative dysplastic kidney tubules which overexpressed PAX2, a potentially oncogenic transcription factor, and BCL2, a cell-survival factor, surrounded by metaplastic, alpha smooth-muscle actin-positive stroma: similar patterns have been observed in patients with non-syndromic multicystic dysplastic kidneys.

CONCLUSIONS

Our results describe a new type of urinary-tract malformation associated with Kallmann's syndrome. However, since multicystic kidneys tend to involute, only when more Kallmann's syndrome patients are screened in utero or in early childhood using structural renal scans, will it be possible to establish whether multicystic kidney disease is a bona-fide part of the syndrome.

Radioiodine treatment of Graves' disease in young people

In Europe young patients with Graves' disease are usually treated with antithyroid drugs initially, then if hyperthyroidism recurs after a prolonged course of such medication, they are offered definitive treatment by subtotal or total thyroidectomy. Neither of these forms of treatment is free from problems. Impressed with the simplicity and safety record of radioiodine therapy, we have treated 8 young patients with radioiodine. The patients all presented with typical Graves' disease and relapsed after 18-24 months of treatment with antithyroid drugs. They were then given the option of a further course of antithyroid medication or definitive treatment with radioiodine or surgery. Those who opted for radioiodine were treated with 131iodine in a dose of 300 MBq with the intention of ablating the thyroid. Antithyroid medication was resumed for 4-6 months and then withdrawn. Four patients became hypothyroid after a single dose of radioiodine but 4 needed a second dose. All became hypothyroid within 2 years. No adverse effects were observed, in particular no patient showed any deterioration in their eye disease. Radioiodine offers a simple, effective and inexpensive method of treatment for Graves' disease in young patients. There are no immediate adverse effects and, although some theoretical concerns remain, to date the long-term safety record of thyroid ablation is excellent and the potential risks seem to us to be outweighed by the advantages. Even when a moderately high initial dose of radioiodine is used, a second dose may be needed.

Both insulin sensitivity and insulin clearance in children and young adults with type I (insulin-dependent) diabetes vary with growth hormone concentrations and with age

AIMS/HYPOTHESIS

We measured insulin clearance rates in children and young adults with Type I (insulin-dependent) diabetes mellitus to establish their relation with insulin sensitivity and with factors such as growth hormone secretion and body mass index.

METHODS

We studied 46 subjects mean (range) age 14.4 (9.8-24.6) years), body mass index 21.1 (15.8-29.6) Kgm2[ using an overnight (1800-0800 hours) variable rate insulin infusion euglycaemic clamp protocol (5 mmol/l). Plasma free insulin concentrations during steady-state euglycaemia were used as an index of insulin sensitivity and insulin clearance determined as a ratio of insulin infusion rate to plasma free insulin.

RESULTS

During steady-state euglycaemia (0500-0730 hours), insulin sensitivity mean (SEM) plasma insulin 0.020 (0.002) mU/l[ and insulin clearance rates 19.1 (1.8) ml.kg-1.min[ varied with age non-linearly and in a reciprocal fashion to each other (cubic regression F = 4.09, p = 0.01; F = 3.55, p = 0.02, respectively). Insulin sensitivity was negatively related to BMI (r = -0.37, p = 0.011) and mean overnight growth hormone concentrations (r = -0.40, p = 0.007). Insulin clearance was only related to growth hormone concentrations (r = -0.37, p = 0.014). These relations were still evident after stepwise multiple regression analysis (potential determinants: C peptide, sex, age, puberty stage, HbA1c, duration of diabetes): insulin sensitivity r = 0.55, p < 0.001; insulin clearance r = 0.37, p < 0.02.

CONCLUSIONS/INTERPRETATION

Insulin clearance rates vary with age in young subjects with Type I diabetes and are highest during mid-adolescence when insulin sensitivity is at its lowest. Both insulin sensitivity and insulin clearance are related to circulating growth hormone concentrations.

The strengths and limitations of parental heights as a predictor of attained height

Mid-parental heights are widely used to help assess an individual child's growth. However, the methods in use vary, and most make no allowance for extremes of parental height. This study aimed to examine the actual distribution of parental heights in a survey population and the relation with their children's heights. The heights of 419 representatively sampled children aged 8-9 years were compared with their reported mid-parental heights, all expressed as standard deviation scores (SDS). These confirmed previous predictions that 90% of the children's heights would fall within 1.5 SDS (approximately two centile spaces) of their mid-parental heights. However, where parents were unusually tall or short, their children were relatively less tall or short, respectively, and the mid-parental height was a poor predictor of attained height. A simple calculator for expected height centile is described that automatically adjusts for this regression to the mean. Of 13 children below the second centile for height, eight were within two centile spaces (90% range) of their mid-parental height SDS. However, when allowance was made for regression to the mean, only three of 13 were within the 90% range. Although mid-parental height provides a useful guide to expected height centile for children and parents of average stature, it can be misleading when used to assess short children.

Hypertonic saline test for the investigation of posterior pituitary function

The hypertonic saline test is a useful technique for distinguishing partial diabetes insipidus from psychogenic polydipsia, and for the diagnosis of complex disorders of osmoreceptor and posterior pituitary function. However, there is little information concerning its use in childhood. The experience of using this test in five children (11 months to 18 years) who presented diagnostic problems is reported. In two patients, in whom water deprivation tests were equivocal or impractical, an inappropriately low antidiuretic hormone (ADH) concentration (< 1 pmol/l) was demonstrated in the presence of an adequate osmotic stimulus (plasma osmolality > 295 mosmol/kg). In two children--one presenting with adipsic hypernatraemia and the other with hyponatraemia complicating desmopressin treatment of partial diabetes insipidus--defects of osmoreceptor function were identified. Confirming a diagnosis of idiopathic syndrome of inappropriate ADH secretion (SIADH) was possible in a patient with no other evidence of pituitary dysfunction. The hypertonic saline test was well tolerated, easy to perform, and diagnostic in all cases.

The effects of recombinant human IGF-I administration on concentrations of acid labile subunit, IGF binding protein-3, IGF-I, IGF-II and proteolysis of IGF binding protein-3 in adolescents with insulin-dependent diabetes mellitus

The long term therapeutic potential of recombinant human (rh) IGF-I administration in insulin-dependent diabetes mellitus (IDDM) may be determined by changes in the IGF binding proteins (IGFBPs) and thus the bioavailability of IGF-I. We have therefore studied the effects of a single subcutaneous dose of rhIGF-I (40 micrograms/kg at 1800 h), when compared with an untreated control night, in 17 subjects with IDDM, on serum concentrations of IGF-I, IGF-II, IGFBP-3, acid labile subunit (ALS), and IGFBP-3 proteolysis. Mean (+/- S.E.M.) IGF-I levels increased from 242 +/- 30 ng/ml to 399 +/- 26 ng/ml (P = 0.01) after rhIGF-I whereas IGF-II levels declined from 600 +/- 45 ng/ml to 533 +/- 30 ng/ml. There was a small overnight reduction in baseline ALS levels from 48 +/- 2.8 to 44.5 +/- 3.2 micrograms/ml (P = 0.04) after rhIGF-I administration. An early fall in IGFBP-3 concentrations on the control night was not seen after rhIGF-I and overall mean levels were increased (5.2 +/- 0.2 micrograms/ml vs 4.9 +/- 0.2 micrograms/ml, P = 0.04, on the control night). On the baseline night, IGFBP-3 levels correlated with the sum of IGF-I and IGF-II (r = 0.73, P = 0.02) and with levels of the ALS (r = 0.7, P = 0.002). However after rhIGF-I, the sum of IGF-I and IGF-II no longer correlated with IGFBP-3, whereas the relationship with ALS was maintained. Immunoblot studies in six subjects indicated that 60%-70% of the IGFBP-3 was detected as a low molecular weight fragment at 1900 h on both study nights, but the amount of fragment declined to approximately 50% at 0100 h and 45% at 0700 h. In conclusion, despite a slight but significant fall in ALS, IGFBP-3 levels rise after rhIGF-I administration in IDDM. This cannot be explained by alterations in IGFBP-3 proteolysis, and may relate to the relative stability of ALS/IGFBP-3 when complexed principally with IGF-I rather than IGF-II.

The relationship between overnight GH levels and insulin concentrations in adolescents with insulin-dependent diabetes mellitus (IDDM) and the impact of recombinant human insulin-like growth factor I (rhIGF-I)

OBJECTIVE

We examined the relationship between GH concentrations and free insulin concentrations, used as an index of insulin sensitivity, before and after recombinant human insulin-like growth factor I (RhIGF-I) administration in adolescents with insulin-dependent diabetes mellitus (IDDM).

DESIGN AND PATIENTS

Growth hormone concentrations were assessed by a peak detection programme (Pulsar) on a control night (2000 h-0800 h) and a night when rhIGF-I administered in a subcutaneous dose of 40 micrograms/kg at 1800 h to 16 adolescent subjects. Stable euglycaemia was maintained by a continuous intravenous insulin infusion and changes in free insulin levels on the two nights were compared with growth hormone data.

RESULTS

Mean overnight GH concentrations (2000 h-0800 h) on the control night were positively related to glycated haemoglobin (Hba1) concentrations (r = 0.63; P < 0.01) and were reduced following rhIGF-I administration (24.9 +/- 3.6 mU/I on the control night versus 17.4 +/- 2.2 mU/I after administration, P = 0.01). The mean GH pulse amplitude on the control night was related to the change in GH levels after rhIGF-I (rs = -0.66, P < 0.001). Multiple regression analysis revealed that mean GH pulse amplitude was the only determinant of free insulin concentrations (0500 h-0700 h on both study nights (P < 0.01). The percentage change in mean growth hormone pulse amplitude between the two nights was related to the percentage reduction in free insulin concentrations (r = 0.53, P = 0.03).

CONCLUSIONS

Growth hormone pulse amplitude is related to early morning insulin sensitivity in adolescents with IDDM on control nights and after rhIGF-I administration. The reduction in insulin levels following rhIGF-I may be linked to the change in GH pulse amplitude and not just to direct insulin-like actions. Individuals with the higher GH (and thus HbA1 levels) were most sensitive to the GH-suppressive effects of rhIGF-I.

Growth hormone insulin-like growth factor I axis in insulin-dependent diabetes mellitus

Growth hormone (GH) hypersecretion and relative insulin-like growth factor I (IGF-I) deficiency have been implicated in the development of insulin resistance, poor metabolic control, and impaired growth during puberty in insulin-dependent diabetes mellitus (IDDM). Portal levels of insulin are critical for the integrity of the hepatic GH receptor and suppression of the inhibitory IGF-binding protein I. Increasing insulin doses during puberty will result in adequate portal levels of insulin and thus restore IGF-I levels and IGF bioactivity, but at the risk of nocturnal hypoglycaemia and weight gain. Restoration of normal circulating levels of IGF-I using the recombinant peptide will lead to reductions in GH levels and improved insulin sensitivity. Given as a daily subcutaneous injection, low-dose recombinant human IGF-I (40 micrograms/kg/day) could prove to be a useful adjunct to standard insulin therapy during puberty in IDDM. The reduced and more stable insulin requirement might reduce the risks of nocturnal hypoglycaemia and weight gain. However, whereas intensified insulin therapy will reduce the risk of microangiopathic complications, the benefits of combination therapy have not been proven. The role of recombinant human IGF-I in the treatment of IDDM needs to be tested by long-term controlled trials.

The effects of repeated daily recombinant human insulin-like growth factor I administration in adolescents with type 1 diabetes

Reduced insulin-like growth factor bioactivity has been linked to poor metabolic control and growth hormone hypersecretion in adolescents with Type 1 diabetes. The safety and efficacy of recombinant human insulin-like growth factor I administered subcutaneously in a dose of 40 micrograms kg-1 for 28 days was studied in a group of 6 adolescent male subjects with Type 1 diabetes (aged 13.6-19.4 years, puberty stage 3-5). After a 4-week run-in period (week -4 day 0) recombinant human insulin-like growth factor I was administered for 4 weeks (day 0 to week +4) before a run-out of a further 4 weeks duration (week +4 to +8). HbA1c levels were measured throughout the study and overnight profiles were undertaken to study levels of insulin-like growth factor 1, insulin-like growth factor binding protein-3, and growth hormone concentrations (week -1, day 0, and week +4). The injections were well tolerated and hypoglycaemia was not problematic at any stage of the study. Recombinant insulin-like growth factor I administration appeared to lead to a sustained increase in insulin-like growth factor I levels (week -1; 198 +/- 16 ng ml-1, week +4; 422 +/- 18 ng ml-1, mean +/- SEM; p = 0.03). Insulin-like growth factor binding protein-3 concentrations (n = 6) increased in 5 subjects (week -1; 4.5 +/- 0.3 micrograms ml-1, week +4; 5.1 +/- 0.4 micrograms ml-1) and mean overnight growth hormone decreased (week -1; 14.0 +/- 3.1 mUI-1, week +4; 7.6 +/- 1.7 mUI-1) during the period of study but these differences were not statistically significant. HbA1c levels fell significantly at the time of rhIGF-I administration (day 0; 10.4 +/- 1.9% vs week +4; 9.4 +/- 1.9%; p = 0.03) despite a reduction in subcutaneous isophane insulin dose from 0.50 +/- 0.02 U kg-1 to 0.41 +/- 0.02 U kg-1 (p = 0.03). There was no significant change in biochemical and haematological indices, glomerular filtration rate or urinary albumin excretion. The restoration of IGF-I levels in adolescents with Type 1 diabetes may have a beneficial impact on glycaemic control.