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Pituitary adenomas in childhood

S.M. SHALET

Pituitary adenomas are uncommon in childhood (Zimmerman, 1969). The majority of pituitary adenomas are benign hormonally active tumours arising from the 5 hormonal secreting cell types of the adenohypophysis (Asa and Kovacs, 1983). With the availability of modern immunohistochemical techniques it is apparent that only 25% of pituitary adenomas are non-functioning.

In paediatric practice the important hormonally active adenomas are GH (gigantism), prolactin and ACTH (Cushing's disease). Both functional and non-functional pituitary tumours may be associated with hypopituitarism resulting from compression of the normal pituitary tissue or from tumour interfering with transport and synthesis of hypothalamic releasing hormones. This may lead to impaired growth, hypothyroidism, hypoadrenalism and failure of normal pubertal development.

Gigantism

The excessive secretion of GH before fusion of the epiphyses leads to gigantism. After fusion it produces the typical features of acromegaly. In nearly all cases, gigantism results from a pituitary tumour. Some tumours are mixed and

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Thyrotoxicosis in childhood

Hans Perrild and Bendt Brock Jacobsen

Thyrotoxicosis during the first two decades of life is rare compared to that in adults, with an incidence of 0.8 per 100000 children per year (1). This limits the experience in the paediatric clinics, and adult treatment strategies are often applied to the thyrotoxic child.

About 95% of thyrotoxic children have Graves' disease (1, 2), in contrast to findings in adults where a significant number of toxic adenomas and multinodular toxic goitres are seen, especially in areas with a relatively low iodine intake (3). It is suggested that Graves' disease in childhood is a self-limiting disorder with a remission rate of 25% every 2 years (4). These observations have to be considered in the choice of therapy.

There are three principal treatments today: antithyroid drugs (ATD), surgery or radioiodine. It is well known that the primary management of thyrotoxicosis in adults is different in Europe, Japan and the USA (5).

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Type 2 diabetes in children in the Netherlands: the need for diagnostic protocols

Joost Rotteveel, Eline J Belksma, Carry M Renders, Remy A Hirasing, and Henriette A Delemarre-Van de Waal

Objective: The worldwide trend towards obesity in childhood is also observed in the Netherlands and one of the consequences may be type 2 diabetes. In this study, we assessed the number of children with type 2 diabetes, diagnosed by paediatricians, in the Netherlands.

Methods: In 2003 and 2004 the Dutch Paediatric Surveillance Unit, a nationwide paediatric register, was used to assess new cases of diabetes mellitus. Data on socio-demographic and clinical characteristics were collected by means of a questionnaire. A second questionnaire was sent to the reporting paediatrician if the diagnosis was inconclusive or if the diagnosis was type 1 diabetes in combination with overweight or obesity, according to international criteria.

Results: During the 24 months of registration, the paediatricians reported 1142 new cases of diabetes, 943 of which were eligible for analysis. Initially, 14 patients (1.5%) were reported with type 2 diabetes. Only seven of these patients were classified as type 2 diabetes according to the ADA criteria, as information on C-peptides or antibodies was often missing. Based on clinical characteristics, the other seven patients were very likely to have type 2 diabetes. After the second questionnaire, six more patients met the ADA criteria and two were very likely to have type 2 diabetes. Most of the patients were female (95%), 14% were of Turkish and 18% of Moroccan origin.

Conclusion: This study shows a discrepancy between the number of patients with type 2 diabetes diagnosed by paediatricians in daily practice and diagnosed according to the ADA criteria. Moreover, a considerable amount of reported patients were misclassified. Finally, 2.4% patients were classified as (very likely) type 2 diabetes. The development of programmes and protocols for prevention, diagnosis and classification applicable in daily practice is warranted.

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Comorbidity and cardiovascular risk factors in adult GH deficiency following treatment for Cushing's disease or non-functioning pituitary adenomas during childhood

Oskar Ragnarsson, Charlotte Höybye, Peter J Jönsson, Ulla Feldt-Rasmussen, Gudmundur Johannsson, Beverly M K Biller, and Maria Kołtowska-Häggström

Objective

Cushing's disease (CD) and non-functioning pituitary adenoma (NFPA) are rare in paediatric patients. The aim of this study was to describe long-term consequences in adults with GH deficiency (GHD) treated for CD or NFPA during childhood.

Design, patients and methods

This was a retrospective analysis of data from KIMS (Pfizer International Metabolic Database). Background characteristics, anthropometry and comorbidity were studied in 47 patients diagnosed with childhood-onset (CO)-CD and 62 patients with CO-NFPA. Data from 100 ACTH-sufficient patients with CO-idiopathic hypopituitarism (CO-Idio) were used for comparison. Cardiovascular risk profile was analysed at baseline and at 1 year on GH treatment in a subgroup of patients (17 CO-CD, 24 CO-NFPA and 55 CO-Idio) not receiving GH treatment at study entry.

Results

The median age at diagnosis of pituitary tumour was 14.0 years (range 10–17) in patients with CO-CD and 13.7 years (range 8–17) in CO-NFPA. In addition to GHD, 41% of patients with CO-CD had three or four other pituitary hormone deficiencies compared with 78% of patients with CO-NFPA (P<0.001). Eighty-nine per cent of patients with CO-CD had height SDS lower than 0 compared with 61% of patients with CO-NFPA (P=0.002). Hypertension was more common in CO-CD compared with CO-Idio (23 vs 9%, P=0.018). At 1 year on GH treatment, total- and low-density lipoprotein-cholesterol decreased significantly in CO-CD but not in CO-NFPA.

Conclusion

Adult patients with GHD following treatment for paediatric CD and NFPA have long-term adverse consequences. Despite more severe hypopituitarism in CO-NFPA, patients with CO-CD have more frequently compromised final stature.

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Paediatric population pharmacokinetic modelling to assess hydrocortisone replacement dosing regimens in young children

Robin Michelet, Johanna Melin, Zinnia P. Parra-Guillen, Uta Neumann, J Martin Whitaker, Viktoria Stachanow, Wilhelm Huisinga, John Porter, Oliver Blankenstein, Richard J. Ross, and Charlotte Kloft

Context:

Accurate hydrocortisone dosing in children with adrenal insufficiency is important to avoid the risks of over and under treatment including iatrogenic Cushing’s syndrome and adrenal crisis.

Objective:

To establish a population pharmacokinetic model of hydrocortisone in children and use this to refine hydrocortisone replacement regimens.

Design and methods:

Pharmacokinetic study of hydrocortisone granules, available in 0.5, 1, 2 and 5 mg dose strengths, in 24 children with adrenal insufficiency aged 2 weeks to 6 years. Cortisol concentrations quantified by LC-MS/MS were used to refine an adult pharmacokinetic model to a paediatric population model which was then used to simulate seven different hydrocortisone treatment regimens.

Results:

Pre-dose cortisol levels were undetectable in 54% of the 24 children. The developed pharmacokinetic model had good predictive performance. Simulations for the seven treatment regimens using either three- or four-times daily dosing showed treatment regimens delivered an AUC0- 24h within the 90% reference range for healthy children except in neonates where two regimens had an AUC below the 5th percentile. Cortisol concentrations at individual time points in the 24 h were outside the 90% reference range for healthy individuals in 50%, 55–65% and 70–75% for children, infants and neonates, respectively, with low cortisol levels being most prevalent.

Conclusions:

Current paediatric hydrocortisone treatment regimens based on either three- or four-times daily administration replicate cortisol exposure based on AUC0- 24h, but the majority of cortisol levels are above or below physiological cortisol levels with low levels very common before the next dose.

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Undescended testes: a consensus on management

E Martin Ritzén

The mode of treatment best for undescended testes is controversial, and local traditions often override knowledge gained from randomized controlled studies. In order to reach a consensus within the Nordic countries on the current state-of-the-art of treatment, a group of specialists in testicular physiology, paediatric surgery/urology, endocrinology, andrology, pathology and anaesthesiology from all the Nordic countries met for 2 days. Before the meeting, reviews of the literature had been prepared by the participants. Judging from published meta-analyses, hormonal treatment has low efficacy. Although 15–20% of retained testes descend during hormonal treatment, one-fifth of these re-ascend later on. Also, treatment with human chorionic gonadotropin (hCG) may be harmful to future spermatogenesis through increased apoptosis of germ cells. Orchiopexy, on the contrary, results in about 95% anatomical success, with a low (about 1%) risk of complications. The optimal time for orchiopexy has also been debated. However, a recent randomized controlled study shows that surgery at 9 months of age is followed by a better post-operative growth of the testes than surgery at 3 years, which supports previous arguments for early surgery. The unanimous conclusion of the group was that surgery is generally the preferred mode of treatment, rather than hCG or GnRH treatments. Orchiopexy should be performed between 6 and 12 months of age, or soon after diagnosis, if that occurs later. If a testis is found to be undescended at any age after 6 months, the patient should be referred for surgery. Referral should be to paediatric rather than general surgeons/urologists if the boy is less than 1 year old, if he has bilateral or non-palpable testes, or if he has got relapse of cryptorchidism.

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Prevalence and demographic features of childhood growth hormone deficiency in Belgium during the period 1986-2001

M Thomas, G Massa, M Craen, F de Zegher, JP Bourguignon, C Heinrichs, J De Schepper, M Du Caju, G Thiry-Counson, and M Maes

OBJECTIVE: Since the availability of recombinant human growth hormone (rhGH) all children with growth hormone deficiency (GHD) living in Belgium are offered rhGH treatment after approval by a peer-review board. In this study, we evaluated the prevalence and demographic features of childhood GHD in Belgium during the period 1986-2001 and we compared them with the data from other countries. METHODS: Diagnostic, demographic and baseline auxological data of 714 children diagnosed as having GHD between 1986 and 2001 were retrieved from the database of the Belgian Study Group for Paediatric Endocrinology. RESULTS: The prevalence of GHD in Belgium was estimated to be 1/5600. The origin of GHD was idiopathic (idGHD) in 41% of the patients, congenital (congGHD) in 20% and acquired (acqGHD) in 35%. During the first 4 years (1986-1989) more patients were classified as idGHD; thereafter the distribution between the three aetiology groups did not change. In all groups, boys outnumbered girls but this preponderance was especially pronounced in congGHD patients (male:female=4:1) with a central malformation that associates an anterior pituitary hypoplasia, a missing, fine or normal pituitary stalk and an ectopic posterior pituitary. Thirteen percent of the patients with idGHD, 50% with congGHD and 52% with acqGHD had multiple pituitary deficiencies. Patients with congGHD were the youngest (mean+/-s.d. age: 6.5+/-4.7 years) and were the shortest (-3.0+/-1.3 standard deviation score (SDS)) at the start of rhGH treatment. There was no time trend over the studied period for age and height at onset of GH therapy. CONCLUSION: In Belgium, the prevalence of childhood GHD can be estimated as 1/5600 which is comparable to other recent surveys. The yearly number of new patients for the different aetiologies and the auxological parameters have remained relatively constant over the last 16 years.

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Insulin resistance and obesity in childhood

Francesco Chiarelli and Maria Loredana Marcovecchio

Childhood obesity is a significant health problem that has reached epidemic proportions around the world and is associated with several metabolic and cardiovascular complications. Insulin resistance is a common feature of childhood obesity and is considered to be an important link between adiposity and the associated risk of type 2 diabetes and cardiovascular disease. Insulin resistance is also a key component of the metabolic syndrome, and its prevalence in the paediatric population is increasing, particularly among obese children and adolescents. Several factors are implicated in the pathogenesis of obesity-related insulin resistance, such as increased free fatty acids and many hormones and cytokines released by adipose tissue.

Valid and reliable methods are essential to assess the presence and the extent of insulin resistance, the associated risk factors and the effect of pharmacological and lifestyle interventions. The two most common tests to assess insulin resistance are the hyperinsulinemic euglycemic clamp and the frequently sampled i.v. glucose tolerance test utilizing the minimal model. However, both these tests are not easily accomplished, are time consuming, expensive and invasive. Simpler methods to assess insulin resistance based on surrogate markers derived from an oral glucose tolerance test or from fasting insulin and glucose levels have been validated in children and adolescents and widely used.

Given the strong association between obesity, insulin resistance and the development of metabolic syndrome and cardiovascular disease, prevention and treatment of childhood obesity appear to be essential to prevent the development of insulin resistance and the associated complications.

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ENDOCRINOLOGY AND ADOLESCENCE: Dealing with transition in young patients with pituitary disorders

Emilia Sbardella, Carlotta Pozza, Andrea M Isidori, and Ashley B Grossman

Introduction

The transition age is the period between childhood to adulthood; it refers to a broad set of physical, cognitive and sociocultural modifications, arbitrarily defined as starting in late puberty and ending with full adult maturation. Pituitary disorders in adolescence represent a challenge that requires careful management during the transition to adult care.

Methods

Given the complexity of care of pituitary disorders in the transition age, we have reviewed the relevant medical literature focusing on aetiology, clinical manifestations, treatment strategies of GH deficiency (GHD), hypogonadotrophic hypogonadism (HH) in male and female adolescents, central hypothyroidism (CH), central adrenal insufficiency (CAI) and cranial diabetes insipidus (CDI) at this time. The objective of the present review is to provide an up-to-date evaluation of the transition period to evaluate the specific needs of adolescents with chronic pituitary disease in order to optimise their management.

Results

We provide an overview of current clinical management of GHD, HH, CH, CAI and CDI in the transition age.

Conclusions

Specific changes occur in pituitary function during the transition period. A holistic approach including discussion of patients’ concerns and emotional support should constitute a key component of managing pituitary disorders in adolescence. Special transition clinics where paediatric and adult endocrinologists work together, should be increasingly created and strengthened to bridge care, to promote continuity and adherence to treatment and to limit potential negative development, metabolic, skeletal and cardiovascular sequelae of discontinuity of care among adolescents with pituitary disorders.

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The bone mass concept: problems in short stature

E Schoenau, C Land, A Stabrey, T Remer, and A Kroke

Bone densitometry is currently one of the mainstays in the evaluation of systemic bone diseases in adults and is also increasingly used to assess primary or secondary bone disorders in children and adolescents. The purpose of carrying out densitometric studies in such circumstances is to measure the densitometric indicators of bone stability. Following procedures which were established for diagnosing adult osteoporosis, a decrease in densitometric surrogates of bone stability is usually interpreted as indicating increased fracture risk. The most basic densitometric parameter is bone mineral content (BMC), which can be measured with most densitometric techniques. BMC is either defined as the mass of mineral contained in an entire bone or as the mass of mineral per unit bone length. While mineral mass can be expected to be a good surrogate for bone stability, BMC is obviously a size-dependent parameter, since small bones weigh less than big bones. This is a drawback in paediatric use, since many children and adolescents who are examined by densitometry suffer from chronic disorders and are small-for-age. Short children will have a lower BMC than their healthy age-matched peers, even if their (smaller) bones are otherwise completely normal.