Adolescents with partial growth hormone (GH) deficiency develop alterations of body composition after GH discontinuation and require follow-up

Identifying patient-related predictors of permanent growth hormone deficiency

Objective

Isolated childhood growth hormone deficiency (GHD) can persist into adulthood, and re-testing at the transition period is needed to determine whether continued growth hormone therapy is indicated. Here, our objective was to identify predictors of permanent GHD.

Design

Retrospective single-centre study of patients with childhood-onset GHD who were re-tested after adult height attainment.

Methods

Auxological, clinical, laboratory, and MRI data throughout follow-up were collected.

Results

We included 101 patients. At GH treatment initiation, age was 8.1 ± 0.4 years, height -2.25 ± 0.8, and BMI -0.27 ± 0.1 SDS. The 29 (28.7%) patients with persistent GHD had lower height SDS (-2.57 ± 0.1 vs. -2.11 ± 0.1, p<0.001) and mean GH peaks (8.4 ± 1.0 vs.13.2 ± 0.5 mIU/L, p<0.001) at GHD diagnosis; at adult height, they had lower IGF1 (232 ± 19.9 vs. 331 ± 9.1 ng/mL, p<0.001) and higher BMI SDS (-0.15 ± 0.27 vs. -0.73 ± 0.13, p<0.005). By multivariate analysis, the best predictive model included height and BMI SDS, both GH peaks, and MRI findings at diagnosis. Patients with height at diagnosis <-3 SDS had a 7.7 (95% IC 1.4-43.1, p=0.02) fold higher risk of persistent GHD after adjustment on BMI SDS. An abnormal pituitary region by MRI was the strongest single predictor (7.2 times, 95% CI 2.7-19.8) and after multivariate analysis adjustment for GH peaks and height SDS at diagnosis, the risk increased to 10.6 (1.8 - 61.3) times.

Conclusions

Height <-3 SDS at GHD diagnosis and pituitary MRI abnormalities should lead to a high index of suspicion for persistent GHD.

The influence of growth hormone on pediatric body composition: A systematic review

BACKGROUND

Growth hormone (GH) affects metabolism and regulates growth in childhood. The most prominent feature of GH deficiency (GHD) in children is diminished height velocity that eventually leads to short stature. In adult-onset GHD, lean body mass (LBM) is reduced, and visceral fat mass (FM) increased. Beneficial effects of GH treatment on body composition in adults with GHD, including an increase in muscle mass and a decrease in FM, are well established. Relatively few studies have investigated the effects of GH treatment on the body composition of pediatric patients with idiopathic or hypothalamic-pituitary disease-associated GH deficiency. This systematic review aimed to summarize available evidence relating to the effects of GH treatment on body composition in children with GHD.

METHODS

The PubMed, Science Direct, Cochrane Trials, and Embase databases, were searched with keywords including "GH", "body composition", "children", and "growth hormone" for English-language articles, published between January 1999 and March 2021. Two reviewers independently evaluated the search results and identified studies for inclusion based on the following criteria: participants had a confirmed diagnosis of GHD (as defined in each study); participants were pediatric patients who were receiving GH or had stopped GH treatment, regardless of whether they were pre- or post-pubertal; the intervention was recombinant human GH (rhGH; somatropin); and outcomes included changes in body composition during or after stopping GH therapy. Data extracted from each study included study quality, study sample characteristics, study interventions, and body composition. Data on fat-free mass and LBM were combined into a single category of LBM.

RESULTS

Sixteen studies reporting changes in body composition (i.e., FM and LBM) associated with GH treatment in children with GHD were identified and included in the review. Collectively, these studies demonstrated that FM decreased, and LBM increased in response to GH replacement therapy.

CONCLUSION

Despite study limitations (i.e., potential effects of diet and physical activity were not considered), we concluded that a periodic body composition assessment is required to ensure that a satisfactory body composition is achieved during GH replacement therapy in children with GHD.

Low muscle mass and strength in pediatrics patients: Why should we care?

Skeletal muscle plays major roles in metabolism and overall health across the lifecycle. Emerging evidence indicates that prenatal (maternal diet during pregnancy and genetic defects) and postnatal factors (physical activity, hormones, dietary protein, and obesity) influence muscle mass acquisition and strength early in life. As a consequence, low muscle mass and strength contributes to several adverse health outcomes during childhood. Specifically, studies demonstrated inverse associations of muscle mass and strength to single and clustered metabolic risk factors. The literature also consistently reports that low muscle mass and strength are associated with reduced bone parameters during growth, increasing the risk of osteoporosis in old age. Furthermore, muscle mass gains are associated with improved neurodevelopment in the first years of life. Given these negative implications of low muscle mass and strength on health, it is crucial to track muscle mass and strength development from childhood to adolescence. Several body composition techniques are currently available for estimation of muscle mass, all with unique advantages and disadvantages. The value of ultrasound as a technique to measure muscle mass is emerging in pediatric research with potential for translating the research findings to clinical settings. For the assessment of muscle strength, the handgrip strength test has been widely employed but without a standardized protocol. Although further research is needed to define normative data and cut points for the low muscle mass and strength phenotype, the use of such non-invasive medical monitoring is a promising strategy to identify early abnormalities and prevent low muscle mass in adulthood.

Growth hormone - past, present and future

Growth hormone (GH) research and its clinical application for the treatment of growth disorders span more than a century. During the first half of the 20th century, clinical observations and anatomical and biochemical studies formed the basis of the understanding of the structure of GH and its various metabolic effects in animals. The following period (1958-1985), during which pituitary-derived human GH was used, generated a wealth of information on the regulation and physiological role of GH - in conjunction with insulin-like growth factors (IGFs) - and its use in children with GH deficiency (GHD). The following era (1985 to present) of molecular genetics, recombinant technology and the generation of genetically modified biological systems has expanded our understanding of the regulation and role of the GH-IGF axis. Today, recombinant human GH is used for the treatment of GHD and various conditions of non-GHD short stature and catabolic states; however, safety concerns still accompany this therapeutic approach. In the future, new therapeutics based on various components of the GH-IGF axis might be developed to further improve the treatment of such disorders. In this Review, we describe the history of GH research and clinical use with a particular focus on disorders in childhood.

Glucose Metabolism in Children With Growth Hormone Deficiency

BACKGROUND

The growth hormone (GH)/insulin-like growth factor 1 (IGF-1) axis has a fundamental impact on glucose metabolism. Therefore, both untreated GH deficiency (GHD) and GH treatment (GHT) may be associated with some metabolic alterations, although the abnormalities of glucose metabolism have been investigated by relatively few studies as main outcomes.

AIM

The present review summarizes the available data on glucose metabolism in children with GHD, providing an overview of the current state of the art in order to better clarify the real metabolic impact of GHD and GHT.

METHODS

Among all the existing studies, we evaluated all original studies that fulfilled our criteria for analysis reporting parameters of glucose metabolism as the primary or secondary objective.

RESULTS

The reported impact of GHD per se on glucose metabolism is quite homogeneous, with the majority of studies reporting no significant difference in metabolic parameters between GHD children and controls. Conversely, GHT proves to be more frequently associated with a subtle form of insulin resistance, while both fasting glucose and HbA1c levels remain almost always within the normal range.

CONCLUSION

The different methods to study glucose metabolism, the heterogeneity of the populations evaluated, the different doses of GH used together with the variable duration of follow-up may be responsible for discrepancy in the results. Long-term longitudinal studies having glucose homeostasis as their primary outcome are still needed in order better to clarify the real metabolic impact of GHD and GHT in children.

Impact of discontinuation of growth hormone treatment on lipids and weight status in adolescents

BACKGROUND

While the main role of growth hormone (GH) replacement therapy in children is to promote linear growth, GH has also an effect on lipids and body composition. There is an ongoing discussion whether discontinuation of GH treatment is associated with deterioration of lipids.

METHODS

We analyzed weight status [as body mass index-standard deviation score (BMI-SDS)], insulin like growth factor (IGF)-1, triglycerides, total, low-density liporptoein (LDL)- and high-density lipoprotein (HDL)-cholesterol at the end of GH treatment and in mean 6 months later in 90 adolescents (53 with GH deficiency, 16 with Turner syndrome [TS] and 21 born small-for-gestational age [SGA]).

RESULTS

After stopping GH treatment, total cholesterol (+10±24 mg/dL vs. -4±13 mg/dL) and LDL-cholesterol (+15±20 mg/dL vs. -6±12 mg/dL) increased significantly higher in severe (defined by GH peak in stimulation test <3 ng/mL) compared to moderate GHD. In patients with TS, total cholesterol (+19±9 mg/dL), LDL-cholesterol (+9±12 mg/dL) and HDL-cholesterol (+4.3±3.5 mg/dL) increased significantly. In adolescents born SGA, triglycerides increased (+34±51 mg/dL) and HDL-cholesterol decreased significantly (-3.8±7.1 mg/dL). In multiple linear regression analyses, changes of total and LDL-cholesterol were significantly negatively related to peak GH in stimulation tests, but not to gender, age at GH start, duration of GH treatment, observation time, changes of BMI-SDS or IGF-1 after the end of GH treatment. The BMI-SDS did not change after the end of GH treatment.

CONCLUSIONS

Discontinuation of GH treatment leads to a deterioration of lipids in TS, SGA and severe but not moderate GHD.

Metabolic alterations in paediatric GH deficiency

Growth hormone (GH) has a large number of metabolic effects, involving lipid and glucose homoeostasis, lean and fat mass. Growth hormone deficiency (GHD) is associated with a metabolic profile similar to the Metabolic Syndrome which is characterized by dyslipidemia, insulin resistance, haemostatic alterations, oxidative stress, and chronic inflammation. GH replacement treatment in GHD children improves these cardiovascular risk factors, while cessation of GH is associated with a deterioration of most of these risk factors. However, it is unclear whether the changes of these risk factors are associated with an increased risk of cardiovascular diseases especially after discontinuing GH treatment. GH treatment itself can lead to insulin resistance, which probably also influences the cardiovascular health status. Therefore, longitudinal studies with the primary outcome cardiovascular diseases are needed in GHD children. Furthermore, new approaches such as metabolomic studies might be helpful to understand the relationship between GHD, GH treatment, and cardiovascular diseases.

Baseline Body Composition in Prepubertal Short Stature Children with Severe and Moderate Growth Hormone Deficiency

Objective. To compare body composition parameters in short children with severe versus moderate and no growth hormone deficiency (GHD). Design and Method. 61 children (40 boys) were studied. Height SDS, BMI Z-score, waist/height ratio (W/HtR), and body composition parameters (BIA) as fat tissue (FAT%), fat-free mass (FFM%), predicted muscle mass (PMM%), and total body water (TBW%) were evaluated. GH secretion in the overnight profile and two stimulation tests and insulin-like growth factor 1 (IGF-1) level were measured. Results. Overall, in 16 (26%) moderate (7.0 > peak GH < 10 ng/mL) and in 11 (18%) severe (GH ≤ 7.0 ng/mL) GHD was diagnosed. In children with sGHD BMI Z-score, W/HtR and FAT% were significantly higher, while FFM%, PMM%, and TBW% were significantly lower versus mGHD and versus noGHD subgroups. No significant differences between mGHD and noGHD were found. There were no differences in height SDS and IGF-1 SDS between evaluated subgroups. Night GH peak level correlated significantly with FAT%, FFM%, PMM%, and TBW%, (p < 0.05) in the entire group. Conclusions. Only sGHD is associated with significant impairment of body composition. Body composition analysis may be a useful tool in distinguishing between its severe and moderate form of GHD.

Natural history of growth hormone deficiency in a pediatric cohort

BACKGROUND/AIMS

Controversies still exist regarding the evaluation of growth hormone deficiency (GHD) in childhood at the end of growth. The aim of this study was to describe the natural history of GHD in a pediatric cohort.

METHODS

This is a retrospective study of a cohort of pediatric patients with GHD. Cases of acquired GHD were excluded. Univariate logistic regression was used to identify predictors of GHD persisting into adulthood.

RESULTS

Among 63 identified patients, 47 (75%) had partial GHD at diagnosis, while 16 (25%) had complete GHD, including 5 with multiple pituitary hormone deficiencies. At final height, 50 patients underwent repeat stimulation testing; 28 (56%) recovered and 22 (44%) remained growth hormone (GH) deficient. Predictors of persisting GHD were: complete GHD at diagnosis (OR 10.1, 95% CI 2.4-42.1), pituitary stalk defect or ectopic pituitary gland on magnetic resonance imaging (OR 6.5, 95% CI 1.1-37.1), greater height gain during GH treatment (OR 1.8, 95% CI 1.0-3.3), and IGF-1 level <-2 standard deviation scores (SDS) following treatment cessation (OR 19.3, 95% CI 3.6-103.1). In the multivariate analysis, only IGF-1 level <-2 SDS (OR 13.3, 95% CI 2.3-77.3) and complete GHD (OR 6.3, 95% CI 1.2-32.8) were associated with the outcome.

CONCLUSION

At final height, 56% of adolescents with GHD had recovered. Complete GHD at diagnosis, low IGF-1 levels following retesting, and pituitary malformation were strong predictors of persistence of GHD.

Alteration of the growth hormone axis, visceral fat dysfunction, and early cardiometabolic risk in adults: the role of the visceral adiposity index

The aim of the study is to clarify the relationship between adipose tissue dysfunction, metabolic profile and growth hormone (GH)/insulin-like growth factor (IGF)-I secretion in healthy adult subjects. We investigated the metabolic profile in a cohort of 231 consecutive healthy subjects in relation to GH, IGF-I levels, and visceral adiposity index (VAI). Anthropometric measures, lipid profile, and glucose and insulin levels during oral glucose tolerance test, Homa-IR and ISI Matsuda, IGF-I and GH peak after GHRH plus Arginine test were analyzed. The subjects with high VAI showed lower GH peak (22.8 ± 11.1 vs. 42.2 ± 21.3 µg/L; p = 0.049) and lower IGF-I (presented as IGF-I under normal range, UNR) (0.54 ± 0.14 vs. 0.64 ± 0.12; p = 0.005) than group with normal VAI. ROC curve analysis identified the cut-off, able to detect subjects with high VAI, i.e., 31.8 µg/L for GH peak and 0.63 for IGF-1 UNR. The subjects with GH peak and IGF-I UNR under the cut-off showed significantly higher levels of VAI, systolic and diastolic blood pressure, glucose and insulin levels, Homa-IR, and lower ISI Matsuda, with a concomitant worse lipid profile (all p < 0.001). A strong relationship between GH axis, VAI and metabolic risk has been demonstrated. A percentage of apparently healthy subjects show a degree of visceral adipose dysfunction associated with GH and IGF-I levels that do not meet the criteria of overt GH deficiency (GHD). Long-term prospective studies could help to clarify and confirm whether a hypothetical condition of subclinical GHD could be taken into account as a new clinical entity.

Reappraisal of serum insulin-like growth factor-I (IGF-1) measurement in the detection of isolated and combined growth hormone deficiency (GHD) during the transition period

OBJECTIVE

To evaluate the accuracy of serum IGF-1 in the detection of isolated (IGHD) or combined growth hormone deficiency (CGHD) at the transition phase.

SUBJECTS AND METHODS

Forty nine patients with GHD during childhood [16 with IGHD (10 men) and 33 with CGHD (24 men); age 23.2 ± 3.5 yrs.] were submitted to an insulin tolerance test (ITT) with a GH peak < 5 µg/L used for the diagnosis of GHD at the transition phase. Pituitary function and IGF-1 measurements were evaluated in the basal sample of the ITT. Transition patients were reclassified as GH-sufficient (SGH; n = 12), IGHD (n = 7), or CGHD (n = 30).

RESULTS

Five (31%) patients with IGHD and 32 (97%) with CGHD at childhood persisted with GHD at retesting. One patient with IGHD was reclassified as CGHD, whereas 3 patients with CGHD were reclassified as IGHD. Mean GH peak was 0.2 ± 0.3 µg/L in the CGHD, 1.3 ± 1.5 µg/L in the IGHD, and 18.1 ± 13.1 µg/L in the SGH group. Serum IGF-1 level was significantly higher in the SGH (272 ± 107 ng/mL) compared to IGHD (100.2 ± 110) and CGHD (48.7 ± 32.8) (p < 0.01). All patients reclassified as CGHD, 86% reclassified as IGHD, and 8.3% reclassified as SGH had low IGF-1 level, resulting in 97.3% sensitivity and 91.6% specificity in the detection of GHD at the transition period; the cutoff value of 110 ng/mL showed 94.5% sensitivity and 100% specificity. Mean IGF-1 values did not differ in IGHD or CGHD associated with one, two, three, or four additional pituitary deficiencies.

CONCLUSION

IGF-1 measurement is accurate to replace ITT as initial diagnostic test for IGHD and CGHD detection at the transition phase.

United States multicenter study of factors predicting the persistence of GH deficiency during the transition period between childhood and adulthood

Background

Many patients with childhood-onset growth hormone (GH) deficiency do not fulfill diagnostic criteria for GH deficiency (GHD) after attainment of adult height and may not require long-term GH treatment. Patients with history of idiopathic GHD (IGHD) pose the greatest management dilemma, as data regarding factors predictive of persistent GHD in this group are lacking.

Objectives

The objective of this study was to assess potential predictors of persistent GHD in a US patient cohort during transition from childhood to adulthood, particularly in patients with history of IGHD.

Methods

We studied 73 US patients with history of childhood-onset GHD screened at 21 US pediatric endocrine centers for a randomized clinical trial of GH replacement after attainment of adult height. The cohort comprised 42 boys/men and 31 girls/women aged14–22 years, who had received ≥1 year of GH treatment and had completed linear growth. The main outcome measures were sensitivity, specificity, positive and negative predictive values (PPV, NPV) of clinical and hormonal factors for persistent GHD (defined a priori in this study as peak GH < 5 μg/L).

Results

For the cohort as a whole, the best predictors of persistent GHD (100% PPV) were history of organic hypothalamic-pituitary disorder or ≥2 additional pituitary hormone deficiencies (PHD). Best predictors of persistent GHD in patients with childhood history of IGHD were standard deviation scores (SDS) for serum insulin-like growth factor binding protein-3 (IGFBP-3) below -2.0, and for insulin-like growth factor-I (IGF-I) below -5.3 (measured ≥6 weeks after completion of GH treatment; PPV 100% for both), and age <4 years at original diagnosis (PPV 89%). IGF-I above -1.6 SDS had 100% NPV.

Conclusions

US patients with an organic cause of childhood-onset GHD or ≥2 additional PHDs may not require GH stimulation testing to reconfirm GHD after completion of childhood treatment. In contrast, patients with idiopathic childhood-onset GHD almost invariably require retesting, as GHD persists in only a minority (those who were very young at initial diagnosis and those who have subnormal IGFBP-3 or extremely low IGF-I after completion of childhood treatment). Subnormal posttreatment IGF-I (<-2.0 SDS) lacked predictive power for persistent GHD, whereas IGF-I > -1.6 SDS was 100% predictive of GH sufficiency.

Subclinical hypopituitarism

The presence of subclinical or minor pituitary hormone deficiencies could be recognised in clinical practice and might represent intermediate situations among normal pituitary hormone secretion and clinical hypopituitarism. However, this entity has not been correctly identified and associated clinical impairment and even more, long-term consequences regarding to morbidity and mortality, strongly related to clinical hypopituitarism, has not been correctly settled. Furthermore, best test or methods for diagnosis and the cut off to define these intermediate situates are also unknown. With this purpose, long-term controlled studies are needed to define correctly this entity, the appropriate methods for diagnosis and the potential benefits of substitutive hormone therapy in detected cases. The present review will focus on the available evidence concerning the prevalence, clinical features and diagnosis of subclinical hypopituitarism.

A reappraisal of diagnosing GH deficiency in adults: role of gender, age, waist circumference, and body mass index

OBJECTIVE

The objective of the study was to reevaluate the diagnostic accuracy of GH peak after GHRH plus arginine test (GHRH+ARG) according to patients' age, body mass index (BMI), and waist circumference to diagnose GH deficiency (GHD).

OUTCOME MEASURES

GH peak after GHRH+ARG and IGF-I levels reported as sd score.

SUBJECTS

Subjects included 408 controls (218 women, 190 men, aged 15-80 yr) and 374 patients with hypopituitarism (167 women, 207 men, aged 16-83 yr).

RESULTS

In the (elderly) healthy subjects 15-25 yr old (young), 26-65 yr old (adults) and older than 65 yr, GH cutoffs were 15.6, 11.7, and 8.5 microg/liter, 11.8, 8.1, and 5.5 microg/liter, and 9.2, 6.1, and 4.0 microg/liter, respectively, in the lean, overweight, and obese subjects. Waist circumference was the best predictor of GH peak (t = -7.6, P < 0.0001) followed by BMI (t = -6.7, P < 0.0001) and age (t = -5.7, P < 0.0001). Based on the old (<9.1 microg/liter) and new GH cutoff, 286 (76.5%) and 276 (73.8%) of 374 hypopituitary patients had severe GHD. The receiving-operator characteristic analysis showed GH cutoffs in line with the third percentile or slightly higher results so that the prevalence of GHD increased to 90.1%.

CONCLUSIONS

The results of the current study show that waist circumference and BMI are the strongest predictors of GH peak after GHRH+ARG followed by age. However, the old cutoff value of 9.0 microg/liter was in line with the new cutoffs in 95% of patients.

Adult GH deficiency throughout lifetime

It is now accepted that adults with severe GH deficiency (GHD) demonstrate impaired physical and psychological well-being and may benefit from replacement with recombinant human GH. Post-marketing surveillance surveys, such as the Pfizer International Metabolic Database (KIMS), were initially set-up to provide safety data on long-term treatment but have the added benefit of providing ongoing observational data on the effect of GH replacement on body composition, lipid and glucose status, hypertension, bone density and quality of life. These data demonstrate that although GHD has clinical impact at all ages, the individual consequences of this condition may take on greater significance at different stages in life. At all ages, accurate, safe diagnosis and appropriate GH dosing are necessary to provide the individual with the best possible outcome.

Likelihood of persistent GH deficiency into late adolescence: relationship to the presence of an ectopic or normally sited posterior pituitary gland

OBJECTIVES

The presence of an ectopic posterior pituitary gland (EPP) in childhood is associated with isolated GH deficiency (IGHD) and multiple pituitary hormone deficiency. GHD in late adolescence has been defined as a peak GH level <5 microg/l. The aim of this study was to identify the likelihood of persistent GHD in late adolescence in patients with an EPP compared with those with a normally sited posterior pituitary (NPP).

METHODS

In 18 patients with an EPP and 15 patients with an NPP, clinical, biochemical and radiographic data were collected.

RESULTS

In the EPP vs. the NPP group, the change in peak GH levels at the end of growth was less (+0.4[95% confidence interval (CI) - 0.8 to 2.7] vs. +4.1[95%CI + 0.4 to +10.5] microg/l, P-value for ancova = 0.03, after adjustment for age and sex). Using a peak GH level of <5 microg/l as a cut-off for GHD, 66% of EPP subjects compared with 40% of NPP subjects had GHD (P = 0.3). Hundred per cent of EPP subjects had a peak GH level on retesting <10 microg/l, compared with 40% of NPP subjects (P < 0.001).

CONCLUSION

It is important to document GH status at the end of growth, even if there is a structural abnormality of the hypothalamic-pituitary axis. The presence of an EPP compared to an NPP increases the likelihood of persistent GHD by 26%. As all EPP patients had a peak GH level of <10 microg/l, the cut-off for persistent GHD in late adolescence may need to be revised.

Transitioning of children with GH deficiency to adult dosing: changes in body composition

As more evidence gathers regarding the beneficial effect of growth hormone replacement therapy (GHRT) on body composition and other parameters in adults with childhood-onset growth hormone deficiency (GHD), questions emerge regarding whether or not GHRT should be discontinued following cessation of statural growth, and the effect of GHRT during the transition period on body composition and related parameters. This review discusses the effect of discontinuation of GHRT following attainment of adult stature, and the treatment and dose effect when GHRT is reinstated. We also review data regarding who should receive GHRT, the criteria for diagnosing persistent GHD, dosing of GHRT and the possibility of a GH 'holiday'.

Evaluation of permanent growth hormone deficiency (GHD) in young adults with childhood onset GHD: a multicenter study

BACKGROUND

Reconfirming the diagnosis of childhood onset growth hormone deficiency (GHD) in young adults is necessary to demonstrate the need for continuation of GH therapy.

OBJECTIVE

This nationally-based study was planned to establish GH status during adulthood in childhood-onset GH deficient patients and to evaluate factors that would predict persistency of the GHD.

METHODS

In this multicenter study, 70 GH deficient patients who had reached final height were evaluated after completion of GH treatment. Fifty-two patients (74%) had isolated GHD and 18 patients (26%) had multiple pituitary hormone deficiency (MPHD). Patients who had reached final height and the pubertal Tanner stage 5 were reevaluated for GH status. After at least 6 weeks of cessation of GH treatment, patients were retested with insulin induced hypoglycemia.

RESULTS

GHD was found to be transient in 64.3% of all patients. Of the isolated GH deficient patients 82.7% had transient GHD, whereas 88.9% of the MPHD patients showed persistent GHD. Comparison of isolated GH deficient and multiple hormone deficient patients indicated higher peak GH, IGF-I and IGFBP-3 levels in isolated GH deficient patients. No parameter was significantly different in the transiently and persistently GH deficient patients with respect to gender. Although specificity of IGF-I value of less than -2 SD showing persistency of GHD was lower than the specificity of IGFBP-3 value of less than -2 SD (65.7% vs 84%), negative predictive values were similar for the two parameters (85.2% and 84%, respectively).

CONCLUSION

Most of the cases of childhood onset GHD are idiopathic and the GHD is transient. In patients with MPHD, GHD is generally permanent. Low IGF-I and IGFBP-3 levels are supporting findings to show persistency of the GHD.

Subnormal serum insulin-like growth factor-I levels in young adults with childhood-onset nonacquired growth hormone (GH) deficiency who recover normal gh secretion may indicate less severe but persistent pituitary failure

CONTEXT

The unexpected observation of a normal GH peak in 22% of young adults with childhood-onset GH deficiency (GHD) and ectopic neurohypophysis has raised questions about the criteria defining GHD in young adults and whether patients with subsequent increases in GH secretion nonetheless have a subtle form of GHD.

OBJECTIVE

Our objective was to determine the characteristics of patients with childhood-onset nonacquired GHD who recover normal peak GH secretion when adult height has been achieved.

DESIGN AND SETTING

We conducted a university hospital-based observational follow-up study.

PARTICIPANTS

Sixty-two patients with ectopic neurohypophysis (n = 24), isolated hypoplastic anterior pituitary (n = 14), or normal hypothalamic pituitary area (n = 24) on magnetic resonance imaging (MRI) at the time of GHD diagnosis underwent reevaluation of the GH-IGF-I axis at a mean age of 16.8 +/- 1.6 yr.

MAIN OUTCOME MEASURES

Outcome measures included clinical and MRI findings and serum IGF-I and peak GH levels.

RESULTS

On retesting, peak GH exceeded 10 microg/liter in 31 patients (50%): six (20%) patients with ectopic neurohypophysis, 10 (32%) patients with initially isolated hypoplastic anterior pituitary, and 15 (48%) patients with normal MRI findings. Among these patients, serum IGF-I levels were significantly lower in patients with ectopic neurohypophysis than in those without structural abnormalities of the hypothalamic pituitary axis (n = 25), but patients without structural abnormalities also had significantly lower serum IGF-I levels than control subjects, after controlling for age, sex, and body mass index (mean serum IGF-I levels of 374 +/- 83 vs. 446 +/- 108 microg/liter; beta-coefficient = -72; P = 0.003).

CONCLUSIONS

The severity of the disease seems to have decreased over time in these patients, who may nonetheless present persistent pituitary failure. The natural history and clinical implications of these findings remain to be clarified. The possibility of a deterioration in the secretion of GH and other pituitary hormones later in life in a subset of these patients warrants the careful long-term follow-up of this population.

Deterioration of growth hormone (GH) response and anterior pituitary function in young adults with childhood-onset GH deficiency and ectopic posterior pituitary: a two-year prospective follow-up study

CONTEXT

The current criteria for definition of partial GHD in young adults are still a subject of debate.

OBJECTIVES

The objective of the study was to reinvestigate anterior pituitary function in young adults with congenital childhood-onset GHD associated with structural hypothalamic-pituitary abnormalities and normal GH response at the time of first reassessment of GH secretion.

DESIGN AND SETTING

This was a prospective explorative study conducted in a university research hospital.

PATIENTS AND METHODS

Thirteen subjects with a mean age of 17.2 +/- 0.7 yr and a peak GH after insulin tolerance test (ITT) higher than 5 microg/liter were recruited from a cohort of 42 patients with childhood-onset GHD and ectopic posterior pituitary at magnetic resonance imaging. GH secretion after ITT and GHRH plus arginine, IGF-I concentration, and body mass index, waist circumference, blood pressure, total cholesterol, and fibrinogen were evaluated at baseline and at 2-yr follow-up.

RESULTS

At mean age of 19.2 +/- 0.7 yr, the mean peak GH response decreased significantly after ITT (P = 0.00001) and GHRH plus arginine (P = 0.0001). GH peak values after ITT and GHRH plus arginine were less than 5 and 9 microg/liter in 10 and eight patients, respectively. Additional pituitary defects were documented in eight patients. Significant changes were found in the values of IGF-I sd score (P = 0.0026), waist circumference (P = 0.00001), serum total cholesterol (P = 0.00001), and serum fibrinogen (P = 0.0004).

CONCLUSIONS

The results of this study underline the importance of further reassessment of pituitary function in young adults with GHD of childhood-onset and poststimulation GH responses suggestive of partial GHD.

Growth hormone replacement throughout life: insights into age-related responses to treatment

The adult growth hormone deficiency (GHD) syndrome is a well-defined clinical entity. Although the symptoms of GHD are not age specific, their relative importance differs depending on the patient's age, and the impact of GHD varies throughout adult life. Ceasing growth hormone (GH) therapy soon after final height in patients with severe GHD potentially limits somatic development by reducing accrual of bone and muscle mass. It is now recognized that the continuation of GH therapy in the transition years is required to achieve adult levels of somatic development. In middle age, the most worrying feature of GHD is the increase in cardiovascular risk, an important component of which is GHD-related dyslipidemia. One of the most profound effects of GH therapy in this age group is the durable reduction in cholesterol levels. Elderly GH-deficient patients experience the symptoms of GHD over and above the signs of normal aging. Perhaps most importantly, these patients have impaired quality of life, with fatigue as a major component. Evidence is growing for improved quality of life with GH therapy in the elderly. This review describes the diagnosis, symptoms and treatment of GHD specific to the different age groups.

The advantage of measuring spontaneous growth hormone (GH) secretion compared with the insulin tolerance test in the diagnosis of GH deficiency in young adults

OBJECTIVE

Reassessment of GH status after the attainment of adult height has important clinical implications in the diagnosis and prognosis of GH deficiency (GHD) in adulthood. The current GH threshold for biochemical definition of GHD in young adults is still a subject of debate.

DESIGN

To investigate the role of pharmacological stimulation tests compared with spontaneous 12-h nocturnal GH secretion in the diagnosis of permanent GHD in young adults with childhood-onset GHD.

PATIENTS

Forty-five young adults (25 males, 20 females) with childhood-onset GHD, height standard deviation score (SDS) -1.1 +/- 1.3 and body mass index (BMI) SDS 1.0 +/- 1.6, were re-evaluated at the age of 19.8 +/- 2.7 years. Sixteen subjects showed a normal pituitary gland on magnetic resonance imaging (MRI), while in 29, consistent structural hypothalamic-pituitary abnormalities were found. GH secretion was assessed by means of an insulin tolerance test (ITT) and a 12-h spontaneous nocturnal profile as well as by IGF-I assessment. The results were compared with those of 43 healthy controls.

RESULTS

Mean 12-h spontaneous nocturnal GH secretion was < 3.1 microg/l (the lowest limit of the normal range) in 36 (80%) of the subjects and > 3.1 microg/l in nine (20%). Of these 36 patients, 29 (80%) had abnormal MRI findings and 20 (55%) had multiple pituitary hormone deficiencies (MPHD). All nine subjects with mean spontaneous GH secretion > 3.1 microg/l had a normal pituitary MRI, isolated GHD and a peak GH response to ITT > 5 microg/l. There was a discordance in 14 patients (31%), who showed a peak GH response to ITT > 5 microg/l but a reduced spontaneous GH secretory capacity; 10 had structural hypothalamic-pituitary abnormalities on MRI.

CONCLUSIONS

Although the ITT provides valuable information and proves to be a sensitive index of permanent GHD, the results of this study emphasize the potential diagnostic value of assessment of 12-h spontaneous GH secretion in young adults with childhood-onset GHD.

Adult growth hormone deficiency: to treat or not to treat

In the last 15 years, it has been recognised that growth hormone deficiency (GHD) in the adult leads to increased morbidity (metabolic syndrome, osteoporosis, muscle wasting, impaired quality of life) and increased incidence of cardiovascular events, a main cause of the increased mortality observed in this population. Pituitary adenomas and their treatment (surgery, radiation) are the most common cause of GHD in adults. Patients with biochemical diagnosis of severe GHD must be offered growth hormone replacement therapy only in the presence of GHD associated morbidity. This treatment improves morbidity, but its effect on mortality remains to be proven. Continuation of treatment for GHD patients in late adolescence to early adulthood, who have reached final height with growth hormone replacement, requires careful clinical judgement.

Approach to the growth hormone-deficient child during transition to adulthood

The observation that some adults with childhood-onset GH deficiency have low bone mineral density, low lean body mass, diminished quality of life, abnormal lipids, and impaired cardiac function, all of which may improve after treatment with GH, has prompted pediatric endocrinologists to reevaluate the practice of discontinuing GH in all patients after attainment of final adult height. The treatment of adolescents to prevent the metabolic complications of GH deficiency is an emerging practice. Studies addressing the evaluation and care of adolescents during this period and the benefits of GH in this setting are conflicting. Our approach in determining which adolescents to retest, when and how to test for persistent GH deficiency, and which subjects to treat is discussed in the context of available clinical data.

Defining Growth Hormone Status in Adults with Hypopituitarism

The identification of adults with severe growth hormone (GH) deficiency (GHD) is not straightforward. The insulin tolerance test remains the gold standard diagnostic test, although other stimuli such as GH-releasing hormone-arginine are gaining acceptance. Insulin-like growth factor-I has a poor diagnostic sensitivity in adult-onset GHD, but is more useful in the subgroup of adults with childhood-onset GHD. Therapeutic developments include increasing recognition of the need to continue GH therapy beyond final height in young adults with severe GHD on retesting. Consensus guidelines have provided a useful algorithm to identify individuals requiring retesting and the number of tests needed. The concept of partial GHD, recognized by paediatric endocrinologists for many years, is being examined in adults with hypothalamic-pituitary disease. Preliminary evidence suggests that this entity is associated with metabolic and anthropometric abnormalities intermediate between those in severe GHD and in healthy controls. It remains to be seen whether this subgroup will derive benefit from GH therapy. To date, therapeutic benefits of GH have been demonstrated only in adults with severe GHD. It is, therefore, imperative that these individuals are unequivocally identified; the diagnosis becomes more uncertain in the presence of obesity, increasing age, and in the absence of additional pituitary hormone deficits.

Growth hormone and the transition from puberty into adulthood

With modern growth hormone (GH) replacement algorithms, children with a diagnosis of growth hormone deficiency achieve at the end of pediatric GH treatment an adult height that is on the average in the normal range. Recent experience with GH replacement in young adults with childhood-onset growth hormone deficiency, however, has shown that these patients present with variable degrees of somatic immaturity. As childhood GH treatment is discontinued when final height is attained, attention moves to the phase of somatic development that follows the end of longitudinal growth, called ''transition'', which had been excluded previously from consideration for either pediatric or adult GH replacement. This article reviews the changes taking place during this phase of development and their relevance for the attainment of adult body maturation. The critical role of GH in this process is described.

Effect on adult height of pubertal growth hormone retesting and withdrawal of therapy in patients with previously diagnosed growth hormone deficiency

CONTEXT

GH replacement therapy in GH-deficient (GHD) patients is usually continued until adult height despite the fact that most of these subjects display a normal secretion when retested at the end of growth. Puberty is the most likely time for normalization of GH secretion.

OBJECTIVES

The objectives of this study are to establish the characteristics and the percentage of the subjects with isolated GHD who normalized secretion at puberty and to compare their statural outcomes with those of the subjects with persistent deficiency treated also after retesting.

DESIGN AND SETTING

This was a prospective, nonrandomized, open-label study conducted in a university research hospital.

PATIENTS AND INTERVENTION

Sixty-nine subjects (40 male, 29 female) with a diagnosis before puberty of isolated GHD by means of arginine and l-dopa tests were reevaluated with the same tests after at least 2 yr of therapy and after puberty onset. If GH peak at retesting was more than 10 microg/liter, therapy was withdrawn.

MAIN OUTCOME MEASURES

Percentage and characteristics of normalized subjects at retesting, outcome of treatment in the subjects treated or untreated to adult height, and factors predictive of growth outcome were measured.

RESULTS

At retesting, 44 subjects (63.7%) confirmed a GH peak less than 10 microg/liter (24 of 40 male and 20 of 29 female). Apart from a less delayed bone age at diagnosis in females, the subjects with confirmed GHD were not different at diagnosis from the other group for height deficit at diagnosis, first year growth response to GH, age and height at puberty onset, height, and IGF-I at retesting. Mean adult height was 165.1 +/- 4.5 cm in the male group treated until adult height vs. 164.0 +/- 3.4 cm in the group who suspended therapy at retesting. Mean adult height was 153.2 +/- 4.1 cm in the female group treated until adult height vs. 152.9 +/- 5.2 cm in the group that suspended therapy at retesting. As regards the parameters expressing the final outcome, the only difference was found in the mean increment adult height-target height sd score in favor of the male group treated until adult height. In both sexes, therapy duration and GH levels at diagnosis and at retesting were unrelated to adult height parameters and to height increments during the period of observation.

CONCLUSIONS

One third of our GHD subjects diagnosed before puberty presented a normal secretion at puberty. The withdrawal of GH therapy in these subjects after retesting was not associated with a catch down growth, and they obtained an adult height similar to those obtained by the GHD subjects treated until adult height. It seems convenient, in subjects with nonsevere GHD, to retest GH secretion at midpuberty and to withdraw treatment for the subjects that are no longer deficient.

Effect of growth hormone therapy and puberty on bone and body composition in children with idiopathic short stature and growth hormone deficiency

The state of bone health and the effect of growth hormone (GH) therapy on bone and body composition in children with idiopathic short stature (ISS) are largely unknown. A direct role of GH deficiency (GHD) on bone density is controversial. Using dual-energy X-ray absorptiometry, this study measured total body bone mineral content (TB BMC), body composition, and volumetric bone mineral density (vBMD) at the lumbar spine (LS) and femoral neck (FN) in 77 children (aged 3-17 years) with ISS (n = 57) and GHD (n = 20). Fifty-five children (GHD = 13) receiving GH were followed over 24 months including measurement of bone turnover. At diagnosis, size-corrected TB BMC SDS was greater (P <or= 0.002) and LSvBMD SDS lower (P < 0.03) than zero in both prepubertal ISS and GHD subjects, but FNvBMD SDS was reduced only in the GHD group (P < 0.05). The muscle-bone relation, as assessed by the BMC/lean mass (LTM) ratio SDS was not different between groups. During GH therapy, prepubertal GHD children gained more height (1.58 [0.9] SDS) and LTM (0.87 [0.63] SDS) compared to prepubertal ISS children (0.75 [0.27] and 0.17 [0.25] SDS, respectively). Percent body fat decreased in GHD (-5.94% [4.29]) but not in ISS children. Total body BMC accrual was less than predicted in all groups accompanied by an increase in bone turnover. Puberty led to the greatest absolute, but not relative, increments in weight, LTM, BMI, bone mass, and LSvBMD. Our results show that children with ISS and GHD differ in their response to GH therapy in anthropometry, body composition, and bone measures. Despite low vBMD values at diagnosis in both prepubertal groups, size-corrected regional or TB bone data were generally within the normal range and did not increase during GH therapy in GHD or ISS children. Growth hormone had great effects on the growth plate and body composition with subsequent gains in height, LTM, bone turnover, and bone mass accrual, but no benefit for volumetric bone density over 2 years.

Impact of growth hormone status on body composition and the skeleton

Severe growth hormone (GH) deficiency (GHD) induces a well-defined clinical entity encompassing, amongst the most reported features, abnormalities of body composition, in particular increased fat mass, especially truncal, and reduced lean body mass. The results from virtually all treatment studies are in agreement that GH replacement improves the body composition profile of GHD patients by increasing lean body mass and reducing fat mass. More recently, the observations have been extended to adults with partial GHD, defined by a peak GH response to insulin-induced hypoglycaemia of 3-7 microg/l. These patients exhibit abnormalities of body composition similar in nature to those described in adults with severe GHD; these include an increase in total fat mass of around 3.5 kg and a reduction of lean body mass of around 5.5 kg. The increase in fat mass is predominantly distributed within the trunk. The degree of abnormality of body composition is intermediate between that of healthy subjects and that of adults with GHD. The impact of GH replacement on body composition in adults with GH insufficiency, although predictable, has not been formally documented. The skeleton is another biological endpoint affected by GH status: in adults with severe GHD, low bone mass has been reported using dual energy x-ray absorptiometry (DEXA) and other quantitative methodologies. The importance of low bone mass, in any clinical setting, is as a surrogate marker for the future risk of fracture. Several retrospective studies have documented an increased prevalence of fractures in untreated GHD adults. Hypopituitary adults with severe GHD have reduced markers of bone turnover which normalize with GH replacement, indicating that GH, directly or via induction of insulin-like growth factor-I, is intimately involved in skeletal modelling. Whilst the evidence that GH plays an important role in the acquisition of bone mass during adolescence and early adult life is impressive, the impact of GHD acquired later in adulthood is less clear. Recently we examined the relationship between bone mineral density (BMD) and age in 125 untreated adults with severe GHD using DEXA. A significant positive correlation was observed between BMD (z-scores) and age at all skeletal sites studied. Overall, few patients, except those aged less than 30 years, had significantly reduced bone mass (i.e. a BMD z-score of less than -2); correction of BMD to provide a pseudo-volumetric measure of BMD suggested that reduced stature of the younger patients may explain, at least in part, this higher frequency of subnormal BMD z-scores. Despite normal BMD, however, an increase in fracture prevalence may still be observed in elderly GHD adults as a consequence of increased falls related to muscle weakness and visual field defects.

Diagnosis of GH deficiency in the transition period: accuracy of insulin tolerance test and insulin-like growth factor-I measurement

OBJECTIVE

A consensus exists that severe growth hormone deficiency (GHD) in adults is defined by a peak GH response to insulin-induced hypoglycemia (insulin tolerance test, ITT) of less than 3 microg/l based on a cohort of subjects with a mean age of 45 years.

DESIGN AND METHODS

By considering one of the following two criteria for the diagnosis of probable permanent GHD, i.e. the severity of GHD (suggested by the presence of multiple pituitary hormone deficiencies (MPHD)) or the magnetic resonance (MR) imaging identification of structural hypothalamic-pituitary abnormalities, 26 patients (17 males, 9 females, mean age 20.8 +/- 2.3 years, range 17-25 years) were selected for re-evaluation of the GH response to ITT and their IGF-I concentration. Eight subjects had isolated GHD (IGHD) and 18 had MPHD. Normative data for peak GH were obtained after ITT in 39 healthy subjects (mean age 21.2 +/- 4.4 years, range 15.1-30.0 years) and the reference range for IGF-I was calculated using normative data from 117 healthy individuals.

RESULTS

Mean peak GH response to ITT was significantly lower in the 26 patients (1.8+/-2.0 microg/l, range 0.1-6.1 microg/l) compared with the 39 controls (18.5 +/- 15.5 microg/l, range 6.1-84.0 microg/l; P < 0.0001). One subject with septo-optic dysplasia had a peak GH response of 6.1 microg/l that overlapped the lowest peak GH response obtained in normal subjects. There was an overlap for IGF-I SDS between subjects with IGHD and MPHD, as well as with normal controls. The diagnostic accuracy of a peak GH response of 6.1 microg/l showed a 96% sensitivity with 100% specificity. The maximum diagnostic accuracy with IGF-I SDS was obtained with a cut-off of -1.7 SDS (sensitivity 77%, specificity 100%) while an IGF-I < or = - 2.0 SDS showed a sensitivity of 62%.

CONCLUSION

Our data show that the cut-off value of the peak GH response to ITT of less than 3 microg/l or 5 microg/l and of IGF-I of less than -2.0 SDS are too restrictive for the diagnosis of permanent GH deficiency in the transition period. We suggest that permanent GHD could be investigated more accurately by means of an integrated analysis of clinical history, the presence of MPHD, IGF-I concentration and the MR imaging findings of structural hypothalamic-pituitary abnormalities.

Do all patients with childhood-onset growth hormone deficiency (GHD) and ectopic neurohypophysis have persistent GHD in adulthood?

Cerebral magnetic resonance imaging findings are of great value for the diagnosis of nonacquired GH deficiency (GHD), and ectopic posterior pituitary hyperintense signal (EPPHS) is a sensitive and specific indicator of hypopituitarism. It has been suggested that patients with childhood-onset GHD and EPPHS do not require additional investigation of GH secretion and should not be retested when adult height is achieved. This recommendation has never been validated through a systematic study. This study aimed to characterize the anterior pituitary function status of patients with EPPHS treated for GHD during childhood after completion of GH therapy when adult height had been achieved. Patients (n = 18; 15 males and three females) with childhood-onset GHD associated with ectopic neurohypophysis were treated with hGH (0.20 +/- 0.05 mg/kg.wk) for 9.9 +/- 4.0 yr (from 6.8 +/- 4.7 to 17.7 +/- 1.3 yr of age) with a mean height gain of 2.6 +/- 1.4 sd score. GH secretion was reevaluated by arginine insulin (n = 15) or propanolol glucagon (n = 3) test after 0.5 +/- 0.6 yr of GH withdrawal. At reevaluation, peak GH was more than 10 mug/liter in four patients (22%; range, 11.7-19.5 microg/liter; group I), between 5 and 10 microg/liter in three patients (17%; range, 7.3-9 mug/liter; group II), and less than 5 microg/liter in 11 patients (61%; range, 0-4.7 microg/liter; group III). A positive correlation was found between serum IGF-I and peak GH levels after attainment of adult height (P = 0.007). Only one of the seven patients who showed increased GH secretion ability in adulthood (groups I and II) demonstrated other hormonal deficiencies (gonadotropin and adrenal insufficiencies). Among the 11 patients with persistent severe GHD (group III), 10 (91%) of the 11 subjects were shown to have multiple pituitary hormone deficits after attainment of adult height. The structure of the hypothalamo-pituitary axis differs among groups [i.e. patients who showed increased GH secretion ability in adulthood (groups I and II) vs. those who remained severely GHD (group III)]. The location of the EPPHS was significantly different among groups (P < 0.003). The EPPHS was found at the median eminence in all but one of group III patients and along the pituitary stalk (proximal stalk) in all but one of group I and II patients. The pituitary stalk was visible and described as normal (n = 1) or thin (n = 6) in all group I and II patients, whereas the pituitary stalk was not visible even after enhancement in seven of the 11 group III patients (P < 0.02). The prevalence of anterior pituitary hypoplasia and the mean height gain sd score were similar in each group. In conclusion, only 61% of patients with childhood-onset GHD and EPPHS remained severely GHD, and thus suitable for GH therapy, in adulthood. Although the pathogenesis of anterior pituitary dysfunction remains unclear in patients with ectopic neurohypophysis, isolated GHD, location of EPPHS along the stalk, and visibility of the pituitary stalk on magnetic resonance imaging findings clearly represent important markers to predict a less severe form of the disease.

Consensus statement on the management of the GH-treated adolescent in the transition to adult care

The European Society for Paediatric Endocrinology held a consensus workshop in Manchester, UK in December 2003 to discuss issues relating to the care of GH-treated patients in the transition from paediatric to adult life. Clinicians experienced in the care of paediatric and adult patients on GH treatment, from a wide range of countries, as well as medical representatives from the pharmaceutical manufacturers of GH participated.

Stepping into Adulthood: The Transition Period

The period of growth from late puberty to full adult maturation, termed the transition period, is important for tissue maturation. Peak bone mass, muscle mass and strength are usually attained in this period. However, it is common clinical practice in children with growth hormone deficiency (GHD) to discontinue growth hormone (GH) treatment in adolescence after attainment of final height. Therefore, patients with childhood-onset GHD that continues into adulthood and who do not receive treatment as adults may experience more severe consequences than patients who acquire GHD as an adult. Recent studies indicate that bone and muscle maturation are attenuated if GH treatment is discontinued at final height. Furthermore, these patients will also develop cardiovascular risk factors that are normally associated with GHD in adults. Much debate surrounds when retesting for GHD should be carried out and when GH treatment should be restarted in adolescents; many of these patients will not have severe GHD according to the criteria set for adults. The transition period is an appropriate time to modify GH doses. Finally, registries exist that have recorded clinical treatment experiences for children and adults. Tools that collect and analyse data provide an important opportunity to investigate issues related to transition.