Hazards of pharmacological tests of growth hormone secretion in childhood

Approach to the Patient: Case Studies in Pediatric Growth Hormone Deficiency and Their Management

CONTEXT

Pathologies attributed to perturbations of the GH/IGF-I axis are among the most common referrals received by pediatric endocrinologists.

AIM

In this article, distinctive cased-based presentations are used to provide a practical and pragmatic approach to the management of pediatric growth hormone deficiency (GHD).

CASES

We present 4 case vignettes based on actual patients that illustrate (1) congenital GHD, (2) childhood GHD presenting as failure to thrive, (3) childhood GHD presenting in adolescence as growth deceleration, and (4) childhood-onset GHD manifesting as metabolic complications in adolescence. We review patient presentation and a management approach that aims to highlight diagnostic considerations for treatment based on current clinical guidelines, with mention of new therapeutic and diagnostic modalities being used in the field.

CONCLUSION

Pediatric GHD is diverse in etiology and clinical presentation. Timely management has the potential not only to improve growth but can also ameliorate or even mitigate adverse metabolic outcomes, which can be directly attributed to a GH deficient state.

The utility of a random cortisol level in determining neonatal central adrenal insufficiency

OBJECTIVES

While it has been established within the first 4 months of life that there is no circadian rhythm, what is unclear is the usefulness of a random serum cortisol (rSC) level in determining neonatal central adrenal insufficiency (CAI). The objective of the study is to determine the utility of using rSC in infants less than 4 months old in the evaluation of CAI.

DESIGN AND PATIENTS

Retrospective chart review of infants who underwent a low dose cosyntropin stimulation test ≤4 months of life with rSC taken as baseline cortisol before stimulation. Infants were divided into three groups: those diagnosed with CAI, those at risk for CAI (ARF-CAI) and a non-CAI group. Mean rSC for each group was compared, and ROC analysis was used to identify rSC cut-off for the diagnosis of CAI.

RESULTS

Two hundred and fifty one infants with the mean age of 50.5 ± 38.08 days, and 37% of these were born at term gestation. The mean rSC were lower in the CAI group (1.98 ± 1.88 mcg/dl) as compared to the ARF-CAI (6.27 ± 5.48 mcg/dl, p = .002) and non-CAI (4.6 ± 4.02 mcg/dl, p = .007) groups. ROC analysis identified a cut-off of rSC level of 5.6 mcg/dL is associated with 42.6% sensitivity and 100% specificity for the diagnosis of CAI in term infants.

CONCLUSIONS

This study demonstrates that though an rSC can be used within the first 4 months of life, its value is best when done ≤30 days of life. Moreover, a diagnostic cut-off for CAI using rSC levels was identified for term infants.

Diagnosis of childhood and adolescent growth hormone deficiency using transcriptomic data

BACKGROUND

Gene expression (GE) data have shown promise as a novel tool to aid in the diagnosis of childhood growth hormone deficiency (GHD) when comparing GHD children to normal children. The aim of this study was to assess the utility of GE data in the diagnosis of GHD in childhood and adolescence using non-GHD short stature children as a control group.

METHODS

GE data was obtained from patients undergoing growth hormone stimulation testing. Data were taken for the 271 genes whose expression was utilized in our previous study. The synthetic minority oversampling technique was used to balance the dataset and a random forest algorithm applied to predict GHD status.

RESULTS

24 patients were recruited to the study and eight subsequently diagnosed with GHD. There were no significant differences in gender, age, auxology (height SDS, weight SDS, BMI SDS) or biochemistry (IGF-I SDS, IGFBP-3 SDS) between the GHD and non-GHD subjects. A random forest algorithm gave an AUC of 0.97 (95% CI 0.93 - 1.0) for the diagnosis of GHD.

CONCLUSION

This study demonstrates highly accurate diagnosis of childhood GHD using a combination of GE data and random forest analysis.

Macimorelin Acetate for the Diagnosis of Childhood-onset Growth Hormone Deficiency

Growth hormone provocation testing forms the cornerstone of the diagnosis of childhood growth hormone deficiency in clinical practice. Despite the widespread use of these tests, various criticisms have been levelled against them, such as the labour-intensive nature of the tests, their potential for serious adverse effects and their questionable reproducibility. Macimorelin acetate, a ghrelin mimetic approved for the diagnosis of adult growth hormone deficiency, could serve an unmet need in the diagnosis of childhood-onset growth hormone deficiency based on its good tolerability and benign side effect profile.

Is the fear from insulin tolerance test in the evaluation of short stature justified?

Among growth hormone (GH) provocative tests, insulin tolerance test (ITT) is considered a valuable test in children with short stature to diagnose GH deficiency. However, many pediatric endocrinologists are reluctant to perform it. We conducted a nationwide survey among all the pediatric endocrine clinics' heads in Israel regarding their position on this issue. We found that the number of endocrine units performing ITT is almost nil. Sense of fear from severe hypoglycemia was a dominating cause for not performing ITT. We review the pros and cons of performing ITT versus other tests, especially glucagon test. Glucagon tolerance test is not considered the test of choice by some endocrinologists but recommended by others including in Israel. We also note the influence of a widely cited report published in 1992 (many times inaccurately) on endocrinologists' views.

CONCLUSION

A nationwide survey in Israel revealed a high rate of reluctance to perform ITT. The rationale behind this attitude was a sense of fear of performing the test by many endocrinologists. We discuss the preferences for choosing GH stimulation tests and the pros and cons of alternatives to ITT. The fear of not performing ITT was not always justified.

WHAT IS KNOWN

• ITT test is considered a gold standard in the evaluation of short stature to diagnose GH deficiency by many endocrinologists.

WHAT IS NEW

• High reluctance rate found in Israel to perform ITT, prompted us to evaluate the attitudes of pediatric endocrinologists around the world showing conflicting ideas. • The role of a single paper sometimes misquoted also contributed to these conflicting results.

A Comparison of the Blood Glucose, Growth Hormone, and Cortisol Responses to Two Doses of Insulin (0.15 U/kg vs. 0.10 U/kg) in the Insulin Tolerance Test: A Single-Centre Audit of 174 Cases

OBJECTIVE

The insulin tolerance test (ITT) is the gold standard endocrine test used to assess the integrity of the growth hormone (GH) and cortisol axes. The ITT has potential risks, and severe hypoglycaemia may necessitate intravenous glucose rescue. There is no clear consensus as to the optimal insulin dose for the ITT. Therefore, we sought to compare the standard dose (0.15 U/kg) and a low-dose ITT (0.1 U/kg).

DESIGN

Single-centre audit of ITT data (2012-2021). Patients and Measurements. Patients who underwent an ITT to assess possible GH deficiency/adrenal insufficiency were included. Glucose, GH, and cortisol were measured at baseline and 30, 45, 60, 90, and 120 minutes following I.V. insulin bolus (0.15 U/kg or 0.10 U/kg).

RESULTS

Of the ITTs performed, only 3/177 (1.7%) did not achieve adequate hypoglycaemia (≤2.2 mmol/L) with a single insulin dose. In total, 174 patients (43.5 ± 12.1 yrs, mean ± standard deviation) were included for analysis (0.15 U/kg: n = 113, 0.10 U/kg: n = 61). All 174 subjects had adequate hypoglycaemia regardless of baseline fasting blood glucose level or insulin dose. Neither nadir glucose nor glucose delta (i.e., baseline minus nadir) differed between insulin doses. Trends in both cortisol and GH responses over time were similar between groups, and a greater proportion of patients receiving the standard dose had an adequate cortisol response (77/106 (72.6%) vs. 32/60 (53.3%), p=0.01). The rates of glucose rescue did not differ in a subset of 79 patients, with on-demand glucose rescue in 4/35 (11%) for the standard dose and 2/44 (5%) for the low dose (p=0.25).

CONCLUSIONS

Our results suggest that the low-dose ITT produces comparable glucose, cortisol, and GH responses to the higher dose. Given the risks associated with hypoglycaemia, the low dose appears to be preferable to the standard dose ITT in most circumstances.

When They're Done Growing, Don't Forget They May Still Need Growth Hormone

The effect of the growth hormone (GH) in promoting linear growth is well known; however, less recognized by practitioners especially pediatric, are its metabolic properties. This may be because the deleterious effects of improperly treated or untreated growth hormone deficiency (GHD) can present beyond the pediatric years. In addition, clinicians may lack familiarity with the potential issues that can arise due to inadequately treated GHD. Considering information from both the basic sciences research and clinical medicine, pediatric practitioners should be cognizant about the metabolic effects of GH. They should also be equipped to provide anticipatory guidance to patients regarding the importance of adherence to therapy in GHD and be prepared to transition patients with permanent GHD from pediatric GH supplementation to adult GH dosing. With a lack of proper transitioning, adverse outcomes may present beyond childhood.

Childhood growth hormone deficiency, a diagnosis in evolution: The intersection of growth hormone history and ethics

In 1958 the first recorded case of a patient treated with human growth hormone for growth hormone deficiency was published. Since that time, the source and availability of human growth hormone have changed. With the increased availability of growth hormone, there has been an uptrend in the level below which childhood growth hormone deficiency is diagnosed based on provocative GH stimulation testing. This increase is despite better specificity of growth hormone assays in addition to a lack of supportive evidence regarding appropriate normal values. With these trends the diagnosis of childhood growth hormone deficiency is evolving, and clinicians should be aware that this may have potential ethical implications.

Adrenal Insufficiency in Children With Eosinophilic Esophagitis Treated With Topical Corticosteroids

OBJECTIVES

The aim of the study was to identify practices of gastroenterologists screening for adrenal insufficiency (AI) and report prevalence of AI in children with eosinophilic esophagitis (EoE) treated with topical corticosteroids (TCS); compare serum dehydroepiandrosterone sulfate (DHEA-S) levels to morning serum cortisol (MSC) levels as screening tool for AI.

METHODS

A multipart study was conducted. In part 1, a survey about screening practices for AI in children with EoE on TCS was sent to gastroenterologists belonging to a PedsGI listserv and to EoE consortia. In part 2, children with EoE on TCS for ≥6 months were prospectively screened for AI with MSC levels. For subjects with a MSC level of <10 μg/dL, a repeat MSC level and/or confirmatory adrenocorticotropic hormone (ACTH) stimulation testing was offered. AI was defined by peak serum cortisol level <18 μg/dL. In part 3, DHEA-S levels were drawn with MSC levels.

RESULTS

Seven percent (16/238) of gastroenterologists screened for AI. Providers in EoE consortia were more likely to screen than nonconsortia providers [9/21(43%) vs 7/217(3%); P = 0.0001]. Thirty-seven children were prospectively screened for AI, and 51% (19/37) had a low MSC level. Ten patients had a low-dose ACTH stimulation test (LDST) after 1 or more low MSC levels. Five percent (2/37) of patients were diagnosed with AI. DHEA-S and MSC levels had a moderate correlation (rs = 0.44, P = 0.03).

CONCLUSIONS

Gastroenterologists belonging to EoE consortia were more likely to screen for AI. Prevalence of AI in our prospective cohort was 5%. DHEA-S has a moderate correlation with MSC levels, but more data is required to assess utility as a screening tool for AI.

The Optimized Calculation Method for Insulin Dosage in an Insulin Tolerance Test (ITT): A Randomized Parallel Control Study

Objective: To explore the most suitable calculation method for insulin dosage in an insulin tolerance test (ITT) and to evaluate the clinical application value of the optimization coefficient (γ). Methods: In this study, 140 adult patients with congenital growth hormone deficiency (GHD) or acquired hypopituitarism were randomized into the following two groups: the conventional group (n = 70) and the optimized group (n = 70). Oral glucose tolerance tests (OGTTs), insulin release tests (IRTs), and ITTs were conducted. For ITTs, insulin doses were the product of body weight (kg) and related coefficient (0.15 IU/kg for the control group and γ IU/kg for the optimized group, respectively). Notably, γ was defined as -0.034 + 0.000176 × AUC_INS + 0.009846 × BMI, which was based on our previous study. Results: In the ITTs, the rate of achieving adequate hypoglycemia with a single insulin dose was significantly higher for the optimized group compared with the conventional group (92.9 vs. 60.0%, P < 0.001). The optimized group required higher initial doses of insulin (0.23 IU/kg). Meanwhile, the two groups did not differ significantly in their nadir blood glucose (1.9 vs. 1.9 mmol/L, P = 0.828). Conclusion: This study confirmed that the proposed optimized calculation method for insulin dosage in ITTs led to more efficient hypoglycemia achievement, without increasing the incidence of serious adverse events.

Dexamethasone Stimulation Test in the Diagnostic Work-Up of Growth Hormone Deficiency in Childhood: Clinical Value and Comparison With Insulin-Induced Hypoglycemia

CONTEXT

dexamethasone has been demonstrated to elicit GH secretion in adults, but few data are available about its effectiveness as a provocative stimulus in the diagnostic work-up of GH deficiency (GHD) in childhood.

OBJECTIVE

to assess the clinical value of dexamethasone stimulation test (DST) as a diagnostic tool for pediatric GHD.

DESIGN AND SETTING

retrospective single-center analysis. The study population included 166 patients with a pathological response to arginine stimulation test (AST, first-line test) and subsequently tested with either insulin tolerance test (ITT) or DST as a second-line investigation between 2008 and 2019.

MAIN OUTCOME MEASURES

comparison between GH peaks and secretory curves induced by ITT and DST; degree of agreement between DST and AST versus ITT and AST.

RESULTS

the pathological response to AST (GH peak < 8 ng/mL) was confirmed by an ITT in 80.2% (89/111) of patients and by a DST in 76.4% (42/55), with no statistical difference between the two groups (p value 0.69). Mean GH peaks achieved after ITT and DST were entirely comparable (6.59 ± 3.59 versus 6.50 ± 4.09 ng/ml, respectively, p 0.97) and statistically higher than those elicited by arginine (p < 0.01 for both), irrespectively of the average GH peaks recorded for each patient (Bland-Altman method). Dexamethasone elicited a longer lasting and later secretory response than AST and ITT. No side effects were recorded after DST.

CONCLUSIONS

DST and ITT confirmed GHD in a superimposable percentage of patients with a pathological first-line test. DST and ITT share a similar secretagogue potency, overall greater than AST.

Comparison of the effects of the L-dopa and insulin tolerance tests on cortisol secretion

PURPOSE

The aims of the present study are to evaluate the effect of L-dopa on the secretion of cortisol and adrenocorticotropic hormone (ACTH) in short children and compare the performance of this test with the insulin tolerance test (ITT) in a large number of patients.

METHODS

A total of 29 short but otherwise healthy children [mean age 9.5 ± 3.1 years (range 3.7-14.9 years)] who had inadequate growth hormone (GH) responses to ITT, which was performed as the first test, were consecutively enrolled in this study. GH, cortisol, and ACTH levels were measured just before administration of L-dopa and then at 30-min intervals afterward over a total time of 120 min. Peak concentrations of cortisol and ACTH exceeding 18 µg/dL (496 mmol/L) and 46 pg/mL (10.2 pmol/L), respectively, were defined as an adequate response.

RESULTS

While the L-dopa test revealed that 26 of the 29 children (89.7%) had peak serum cortisol levels of > 18 µg/dL, the ITT revealed that only 23 children (79.3%) had adequate cortisol responses. The L-dopa test revealed normal ACTH responses (> 46 pg/mL) in 24 (82.8%) patients. Peak cortisol levels were higher in children with normal ACTH responses than in those with subnormal ACTH responses (25.6 ± 6.2 vs. 19.5 ± 6.4 µg/dL, p = 0.054), but the difference observed was statistically insignificant.

CONCLUSION

The results of the current study confirm that the L-dopa test is a reliable test of cortisol secretion. As such, this test may be applicable to assessments of the hypothalamic-pituitary-adrenal axis.

Hypothalamic-pituitary-adrenal (HPA) axis suppression after treatment with glucocorticoid therapy for childhood acute lymphoblastic leukaemia

BACKGROUND

Glucocorticoids play a major role in the treatment of acute lymphoblastic leukaemia (ALL). However, supraphysiological doses can suppress the hypothalamic-pituitary-adrenal (HPA) axis. HPA axis suppression resulting in reduced cortisol response may cause an impaired stress response and an inadequate host defence against infection, which remain a cause of morbidity and death. Suppression commonly occurs in the first days after cessation of glucocorticoid therapy, but the exact duration is unclear. This review is the second update of a previously published Cochrane review.

OBJECTIVES

To examine the occurrence and duration of HPA axis suppression after (each cycle of) glucocorticoid therapy for childhood ALL.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 11), MEDLINE/PubMed (from 1945 to December 2016), and Embase/Ovid (from 1980 to December 2016). In addition, we searched reference lists of relevant articles, conference proceedings (the International Society for Paediatric Oncology and the American Society of Clinical Oncology from 2005 up to and including 2016, and the American Society of Pediatric Hematology/Oncology from 2014 up to and including 2016), and ongoing trial databases (the International Standard Registered Clinical/Social Study Number (ISRCTN) register via http://www.controlled-trials.com, the National Institutes of Health (NIH) register via www.clinicaltrials.gov, and the International Clinical Trials Registry Platform (ICTRP) of the World Health Organization (WHO) via apps.who.int/trialsearch) on 27 December 2016.

SELECTION CRITERIA

All study designs, except case reports and patient series with fewer than 10 children, examining effects of glucocorticoid therapy for childhood ALL on HPA axis function.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection. One review author extracted data and assessed 'Risk of bias'; another review author checked this information.

MAIN RESULTS

We identified 10 studies (total of 298 children; we identified two studies for this update) including two randomised controlled trials (RCTs) that assessed adrenal function. None of the included studies assessed the HPA axis at the level of the hypothalamus, the pituitary, or both. Owing to substantial differences between studies, we could not pool results. All studies had risk of bias issues. Included studies demonstrated that adrenal insufficiency occurs in nearly all children during the first days after cessation of glucocorticoid treatment for childhood ALL. Most children recovered within a few weeks, but a small number of children had ongoing adrenal insufficiency lasting up to 34 weeks.Included studies evaluated several risk factors for (prolonged) adrenal insufficiency. First, three studies including two RCTs investigated the difference between prednisone and dexamethasone in terms of occurrence and duration of adrenal insufficiency. The RCTs found no differences between prednisone and dexamethasone arms. In the other (observational) study, children who received prednisone recovered earlier than children who received dexamethasone. Second, treatment with fluconazole appeared to prolong the duration of adrenal insufficiency, which was evaluated in two studies. One of these studies reported that the effect was present only when children received fluconazole at a dose higher than 10 mg/kg/d. Finally, two studies evaluated the presence of infection, stress episodes, or both, as a risk factor for adrenal insufficiency. In one of these studies (an RCT), trial authors found no relationship between the presence of infection/stress and adrenal insufficiency. The other study found that increased infection was associated with prolonged duration of adrenal insufficiency.

AUTHORS' CONCLUSIONS

We concluded that adrenal insufficiency commonly occurs in the first days after cessation of glucocorticoid therapy for childhood ALL, but the exact duration is unclear. No data were available on the levels of the hypothalamus and the pituitary; therefore, we could draw no conclusions regarding these outcomes. Clinicians may consider prescribing glucocorticoid replacement therapy during periods of serious stress in the first weeks after cessation of glucocorticoid therapy for childhood ALL to reduce the risk of life-threatening complications. However, additional high-quality research is needed to inform evidence-based guidelines for glucocorticoid replacement therapy.Special attention should be paid to patients receiving fluconazole therapy, and perhaps similar antifungal drugs, as these treatments may prolong the duration of adrenal insufficiency, especially when administered at a dose higher than 10 mg/kg/d.Finally, it would be relevant to investigate further the relationship between present infection/stress and adrenal insufficiency in a larger, separate study specially designed for this purpose.

A time-adjusted cortisol cut-off can reduce referral rate for Synacthen stimulation test whilst maintaining diagnostic performance

OBJECTIVE

Cortisol cut-offs can predict requirement for Synacthen stimulation tests (SST). We assessed the performance of a standard cortisol cut-off (375 nmol/L) across the morning and compared this with a time-adjusted cut-off.

DESIGN

Retrospective audit PATIENTS: Community reference set (n=12 550) and SST patients (n=757).

MEASUREMENTS

In the reference population, time-specific cortisol medians were calculated and used to convert cortisol to time-adjusted Multiples of the Median (MoM). In 757 SST patients, the predictive performance of a standard cortisol cut-off (375 nmol/L) and its time-adjusted MoM equivalent were compared.

RESULTS

Median cortisol decreased by ~30 nmol/L per hour between 0700 and 1200h. In the reference population, proportions below the 375 nmol/L cut-off increased throughout the morning (range 35%-64%), whereas using the time-adjusted MoM cut-off proportions were consistent (range 46%-50%), with a 17% maximal difference in referral rates between the two cut-offs after 1100h. A similar pattern was noted in the SST cohort. When a cortisol MoM cut-off was used to predict SST success, the excess proportion of patients tested and misclassification rates were lower and more consistent than when the standard cut-off was used. A median cortisol of 375 nmol/L equated to 444 and 313 nmol/L before 0800 and after 1100 h, respectively.

CONCLUSION

The use of a standard cortisol cut-off results in 17% more patients being referred for SST later in the morning. A time-adjusted cortisol cut-off provides consistent and lower referral rates, whilst maintaining similar or better performance than a standard single cut-off in predicting outcome of SST.

Factors associated with an inadequate hypoglycemia in the insulin tolerance test in Japanese patients with suspected or proven hypopituitarism

We attempted to identify the predictors of an inadequate hypoglycemia in insulin tolerance test (ITT), defined as a blood glucose level higher than 2.8 mmol/L after insulin injection, in Japanese patients with suspected or proven hypopituitarism. A total of 78 patients who had undergone ITT were divided into adequate and inadequate hypoglycemia groups. The relationships between the subjects' clinical parameters and inadequate hypoglycemia in ITT were analyzed. Stepwise logistic regression analysis identified high systolic blood pressure (SBP) and high homeostasis model assessment of insulin resistance (HOMA-IR) as being independent factors associated with inadequate hypoglycemia in ITT. Receiver operating characteristic (ROC) curve analysis revealed the cutoff value for inadequate hypoglycemia was 109 mmHg for SBP and 1.4 for HOMA-IR. The areas under ROC curve for SBP and HOMA-IR were 0.72 and 0.86, respectively. We confirmed that high values of SBP and HOMA-IR were associated with inadequate hypoglycemia in ITT, regardless of the degree of reduction of pituitary hormone levels. Furthermore, the strongest predictor of inadequate hypoglycemia was obtained by using the cutoff value of HOMA-IR. Our results suggest that HOMA-IR is a useful pre-screening tool for ITT in these populations.

Diagnosis of growth hormone deficiency in the paediatric and transitional age

Growth hormone deficiency is a rare cause of childhood short stature, but one for which treatment exists in the form of recombinant human growth hormone. A diagnosis of growth hormone deficiency is made based on auxology, biochemistry and imaging. Although no diagnostic gold standard exists, growth hormone provocation tests are considered the mainstay of diagnostic investigations. However, these must be interpreted with caution in view of issues with variability and reproducibility, as well as the limited evidence-base for cut-off values used to distinguish growth hormone deficient and non-growth hormone deficient subjects. In addition, nutritional and pubertal status can affect results, with no consensus on the role of priming with sex steroid hormones. Difficulties with assays exist both for growth hormone as well as insulin-like growth factor-1. Pituitary magnetic resonance imaging is a useful diagnostic, and possibly prognostic, aid. Although genetic testing is not routine, the discovery of more relevant mutations makes it an increasingly important investigation. Children with growth hormone deficiency are retested biochemically on completion of growth, to assess whether they remain so into adulthood.

The diagnosis and treatment of adrenal insufficiency during childhood and adolescence

The diagnosis and treatment of adrenal insufficiency in childhood and adolescence poses a number of challenges. Clinical features of chronic adrenal insufficiency are vague and non-specific, and mimic many other causes of chronic ill health. A range of diagnostic tests are available for the assessment of adrenal function, all of which have advantages and disadvantages. Cortisol responses to these tests may vary with age and between genders. Knowledge of normal cortisol levels during health and ill health in childhood is also limited, and the cortisol replacement therapies available in clinical practice enable only crude mimicry of physiological patterns of cortisol secretion. An awareness of the limitations of diagnostic tests and treatments is important, and critical clinical assessment, integrating clinical and biochemical data, is essential for the diagnosis and treatment of children with suspected adrenal insufficiency. The aim of this review is to draw on data from clinical studies to inform a pragmatic approach to the child presenting with symptoms of chronic adrenal insufficiency. Clinical features of primary and secondary adrenal insufficiency, and syndromes associated with these diagnoses are described. Factors to consider when selecting a diagnostic test of adrenal function and interpretation of test results are considered. Finally, the limitations of cortisol replacement therapy are also discussed.

Treatment of sulfonylurea and insulin overdose

The most common toxicity associated with sulfonylureas and insulin is hypoglycaemia. The article reviews existing evidence to better guide hypoglycaemia management. Sulfonylureas and insulin have narrow therapeutic indices. Small doses can cause hypoglycaemia, which may be delayed and persistent. All children and adults with intentional overdoses need to be referred for medical assessment and treatment. Unintentional supratherapeutic ingestions can be initially managed at home but if symptomatic or if there is persistent hypoglycaemia require medical referral. Patients often require intensive care and prolonged observation periods. Blood glucose concentrations should be assessed frequently. Asymptomatic children with unintentional sulfonylurea ingestions should be observed for 12 h, except if this would lead to discharge at night when they should be kept until the morning. Prophylactic intravenous dextrose is not recommended. The goal of therapy is to restore and maintain euglycaemia for the duration of the drug's toxic effect. Enteral feeding is recommended in patients who are alert and able to tolerate oral intake. Once insulin or sulfonylurea-induced hypoglycaemia has developed, it should be initially treated with an intravenous dextrose bolus. Following this the mainstay of therapy for insulin-induced hypoglycaemia is intravenous dextrose infusion to maintain the blood glucose concentration between 5.5 and 11 mmol l(-1) . After sulfonylurea-induced hypoglycaemia is initially corrected with intravenous dextrose, the main treatment is octreotide which is administered to prevent insulin secretion and maintain euglycaemia. The observation period varies depending on drug, product formulation and dose. A general guideline is to observe for 12 h after discontinuation of intravenous dextrose and, if applicable, octreotide.

Controversies in the diagnosis and management of growth hormone deficiency in childhood and adolescence

Growth hormone deficiency (GHD) is a rare but important cause of short stature in childhood with a prevalence of 1 in 4000. The diagnosis is currently based on an assessment of auxology along with supporting evidence from biochemical and neuroradiological studies. There are significant controversies in the diagnosis and management of GHD. Growth hormone (GH) stimulation tests continue to play a key role in GHD diagnosis but the measured GH concentration can vary significantly with stimulation test and GH assay used, creating difficulties for diagnostic accuracy. Such issues along with the use of adjunct biochemical markers such as IGF-I and IGFBP-3 for the diagnosis of GHD, will be discussed in this review. Additionally, the treatment of GHD remains a source of much debate; there is no consensus on the best mechanism for determining the starting dose of GH in patients with GHD. Weight and prediction based models will be discussed along with different mechanisms for dose adjustment during treatment (auxology or IGF-I targeting approaches). At the end of growth and childhood treatment, many subjects diagnosed with isolated GHD re-test normal. It is not clear if this represents a form of transient GHD or a false positive diagnosis during childhood. Given the difficulties inherent in the diagnosis of GHD, an early reassessment of the diagnosis in those who respond poorly to GH is to be recommended.

Evidence of hypothalamic-pituitary-adrenal axis suppression during moderate-to-high-dose inhaled corticosteroid use

The possible risk of adverse effects due to regular use of inhaled corticosteroids (ICS) is a real concern. Our aim was to describe the factors that have an impact on hypothalamic-pituitary-adrenal axis suppression (HPA-AS) in children and adolescents taking ICS regularly. The HPA axis status of patients who were on moderate-to-high-dose ICS [>176 and >264 μg/day fluticasone propionate-hydrofluoroalkane (FP-HFA) for patients 0-11 and ≥12 years, respectively] was investigated. Various types of ICS were converted to FP-HFA equivalent according to National Asthma Education and Prevention Program (NAEPP) guidelines. Participants with a baseline (8 a.m.) serum cortisol <15 μg/dL underwent a low-dose ACTH stimulation test (LDAT) to diagnose HPA-AS. Among 91 patients, 60 (75.9 %) participants underwent LDAT, and seven (7.7, 95 % CI 3.5-15.3 %) were diagnosed with HPA-AS. Ciclesonide was more frequently used by the participants with HPA-AS compared to patients with a normal HPA axis (42.9 vs. 4.8 %, p = 0.009). Use of ICS at moderate-to-high doses for at least 7 months distinguished participants with HPA-AS from those with a normal HPA axis. Among the duration, type, and dose of ICS, solely the use of ICS with a body mass index (BMI)-adjusted daily dose of ≥22 μg FP was found to increase the risk for HPA-AS (odds ratio (OR) 7.22, 95 % confidence interval (CI) 1.23-42.26, p = 0.028). The receiver operating characteristics (ROC) curve analysis revealed a cutoff value of 291 μg/day FP (area under the curve (AUC) = 0.840, p = 0.003) for predicting HPA-AS Conclusion: The prevalence of HPA-AS was found to be 7.7 % in children taking not only high-dose ICS but also moderate-dose ICS. Dose alone was found to be an actual risk factor for HPA-AS.

Peak cortisol response to corticotropin-releasing hormone is associated with age and body size in children referred for clinical testing: a retrospective review

Background

Corticotropin-Releasing Hormone (CRH) testing is used to evaluate suspected adrenocorticotropic hormone (ACTH) deficiency, but the clinical characteristics that affect response in young children are incompletely understood. Our objective was to determine the effect of age and body size on cortisol response to CRH in children at risk for ACTH deficiency referred for clinical testing.

Methods

Retrospective, observational study of 297 children, ages 30 days – 18 years, undergoing initial, clinically indicated outpatient CRH stimulation testing at a tertiary referral center. All subjects received 1mcg/kg corticorelin per institutional protocol. Serial, timed ACTH and cortisol measurements were obtained. Patient demographic and clinical factors were abstracted from the medical record. Patients without full recorded anthropometric data, pubertal assessment, ACTH measurements, or clear indication for testing were excluded (number remaining = 222). Outcomes of interest were maximum cortisol after stimulation (peak) and cortisol rise from baseline (delta). Bivariable and multivariable linear regression analyses were used to assess the effects of age and size (weight, height, body mass index (BMI), body surface area (BSA), BMI z-score, and height z-score) on cortisol response while accounting for clinical covariates including sex, race/ethnicity, pubertal status, indication for testing, and time of testing.

Results

Subjects were 27 % female, with mean age of 8.9 years (SD 4.5); 75 % were pre-pubertal. Mean peak cortisol was 609.2 nmol/L (SD 213.0); mean delta cortisol was 404.2 nmol/L (SD 200.2). In separate multivariable models, weight, height, BSA and height z-score each remained independently negatively associated (p < 0.05) with peak and delta cortisol, controlling for indication of testing, baseline cortisol, and peak or delta ACTH, respectively. Age was negatively associated with peak but not delta cortisol in multivariable analysis.

Conclusions

Despite the use of a weight-based dosing protocol, both peak and delta cortisol response to CRH are negatively associated with several measures of body size in children referred for clinical testing, raising the question of whether alternate CRH dosing strategies or age- or size-based thresholds for adequate cortisol response should be considered in pediatric patients, or, alternatively, whether this finding reflects practice patterns followed when referring children for clinical testing.

Electronic supplementary material

The online version of this article (doi:10.1186/s13633-015-0018-y) contains supplementary material, which is available to authorized users.

Hypothalamic-pituitary-adrenal (HPA) axis suppression after treatment with glucocorticoid therapy for childhood acute lymphoblastic leukaemia

BACKGROUND

Glucocorticoids play a major role in the treatment of acute lymphoblastic leukaemia (ALL). However, supraphysiological doses can suppress the hypothalamic-pituitary-adrenal (HPA) axis. HPA axis suppression resulting in reduced cortisol response may cause an impaired stress response and an inadequate host defence against infections, which remains a cause of morbidity and death. Suppression commonly occurs in the first days after cessation of glucocorticoid therapy, but the exact duration is unclear. This review is an update of a previously published Cochrane review.

OBJECTIVES

To examine the occurrence and duration of HPA axis suppression after (each cycle of) glucocorticoid therapy for childhood ALL.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; Issue 6, 2014), MEDLINE/PubMed (from 1945 to June 2014), and EMBASE/Ovid (from 1980 to June 2014). In addition, we searched reference lists of relevant articles, conference proceedings (the International Society for Paediatric Oncology and the American Society of Clinical Oncology from 2005 to 2013), and ongoing trial databases (the ISRCTN register and the NIH register via http://www.controlled-trials.com in June 2014).

SELECTION CRITERIA

All study designs, except case reports and patient series with fewer than 10 children, examining the effect of glucocorticoid therapy for childhood ALL on the HPA axis function.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection. One review author performed the data extraction and 'Risk of bias' assessment, which another review author checked.

MAIN RESULTS

We identified eight studies (total of 218 children), including two randomised controlled trials (RCTs), that assessed the adrenal function. None of the studies assessed the HPA axis at the level of the hypothalamus, pituitary, or both. Due to substantial differences between studies, we could not pool results. All of the studies had some methodological limitations. The included studies demonstrated that adrenal insufficiency occurs in nearly all children in the first days after cessation of glucocorticoid treatment for childhood ALL. The majority of children recovered within a few weeks, but a small number of children had ongoing adrenal insufficiency lasting up to 34 weeks. In the RCTs, the occurrence and duration of adrenal insufficiency did not differ between the prednisone and dexamethasone arms. In one study, it appeared that treatment with fluconazole prolonged the duration of adrenal insufficiency. Furthermore, one of the studies evaluated the presence of infections or stress episodes, or both as a risk factor for adrenal insufficiency. The authors found no relationship between the presence of infection/stress and adrenal insufficiency.

AUTHORS' CONCLUSIONS

We concluded that adrenal insufficiency commonly occurs in the first days after cessation of glucocorticoid therapy for childhood ALL, but the exact duration is unclear. Since no data on the level of the hypothalamus and the pituitary were available, we cannot make any conclusions regarding those outcomes. Clinicians should consider prescribing glucocorticoid replacement therapy during periods of serious stress in the first weeks after cessation of glucocorticoid therapy for childhood ALL to reduce the risk of life-threatening complications. However, more high-quality research is needed for evidence-based guidelines for glucocorticoid replacement therapy.Special attention should be paid to patients receiving fluconazole therapy, and perhaps similar antifungal drugs, as this may prolong the duration of adrenal insufficiency.Finally, it would be relevant to further investigate the relationship between present infection/stress and adrenal insufficiency in a larger, separate study specially designed for this purpose.

The robustness of diagnostic tests for GH deficiency in adults

Since the 1970s, GH treatment has been an important tool in paediatric endocrinology for the management of growth retardation. It is now accepted that adults with severe GH deficiency (GHD) demonstrate impaired physical and psychological well-being and may benefit from replacement therapy with recombinant human GH. There is, however, an ongoing debate on how to diagnose GHD, especially in adults. A GH response below the cut-off limit of a GH-stimulation test is required in most cases for establishing GHD in adults. No 'gold standard' GH-stimulation test exists, but some GH stimulation tests may be more robust to variations in patient characteristics such as age and gender, as well as to pre-test conditions like heat exposure due to a hot bath or bicycling. However, body mass index (BMI) is negatively associated with GH-responses to all available GH-stimulation tests and glucocorticoid treatment, including conventional substitution therapy, influences the GH-responses. Recently, the role of IGF-I measurements in the clinical decision making has been discussed. The aim of this review is to discuss the available GH-stimulation tests. In this author's opinion, tests which include growth-hormone-releasing hormone (GHRH) tend to be more potent and robust, especially the GHRH+arginine test which has been proven to be of clinical use. In contrast, the insulin tolerance test (ITT) and the glucagon test appear to have too many drawbacks.

The intramuscular glucagon stimulation test does not provide good discrimination between normal and inadequate ACTH reserve when used in the investigation of short healthy children

BACKGROUND/AIMS

Few studies have addressed the role of the glucagon stimulation test (GST) in evaluating the hypothalamic-pituitary-adrenal axis in children. We investigated the diagnostic value of the GST in evaluating the adrenocortical response in short healthy children.

METHODS

The GST was performed in 190 children investigated for short stature. A peak cortisol >500 nmol/l was considered a normal response. In the 45 (23.7%) with subnormal response, a 250-μg ACTH test was done.

RESULTS

The rate of subnormal adrenal response to GST was higher among boys (33.9 vs. 8.9%, p < 0.001) and among children ≥6 years than among younger children (32.7 vs. 18.4%, p < 0.02). Both mean basal and peak cortisol levels were higher in girls than in boys: 381 ± 165 vs. 319 ± 151 nmol/l (p = 0.003) and 741 ± 102 vs. 595 ± 208 nmol/l (p < 0.001), respectively. Peak cortisol on GST was associated with basal cortisol (r = 0.45, p < 0.001) but not with glucose nadir (r = -0.31, p = 0.67), peak GH (r = 0.069, p = 0.33) or BMI-SDS (r = -0.08, p = 0.28). Peak cortisol was >500 nmol/l in all the patients undergoing an ACTH stimulation test.

CONCLUSIONS

Since adrenal response to GST is age- and gender-related and the false-positive rate is high, its routine performance in healthy children warrants reconsideration.

L-dopa is a potent stimulator of cortisol in short children

AIMS

In this study, we evaluated the diagnostic usefulness of oral L-dopa as a stimulatory agent for cortisol.

METHODS

In 27 short children that were evaluated for possible growth hormone deficiency (GHD), the levels of serum GH and cortisol were determined after oral L-dopa administration and after i.m. glucagon administration. We defined cortisol concentrations >18 μg/dl (496 nmol/l) as adequate response. Peak GH concentration <10 ng/ml in both tests defined GHD.

RESULTS

Twenty-five out of the 27 children (93%) studied showed a normal cortisol response, i.e. a peak serum cortisol >18 μg/dl in the L-dopa test, whereas 19 children (70%) had a normal cortisol response after stimulation with glucagon. In the children with normal cortisol response in both tests, the mean peak serum cortisol concentration was 28.7 (SD 1.59) after L-dopa and 26.65 (SD 1.26) μg/dl after glucagon administration. There was no statistically significant difference in peak serum cortisol response to L-dopa between GH-deficient and GH-sufficient children [25.90 (SD 4.9) vs. 29.87 (SD 9.9) μg/dl, respectively].

CONCLUSIONS

These results clearly suggest that L-dopa administration is a potent stimulus for cortisol secretion at least in short children.

Pharmacokinetics and pharmacodynamics of orally administered clonidine: a model-based approach

BACKGROUND/AIMS

The oral clonidine test is a diagnostic procedure performed in children with suspected growth hormone (GH) deficiency. It is associated with untoward effects, including bradycardia, hypotension and sedation. Serum clonidine levels have not previously been assessed during this test.

METHODS

In 40 children referred for an oral clonidine test, blood samples were drawn for clonidine and GH. Vital statistics and sedation scores were recorded until 210 min post-dose. We explored the relationship between clonidine concentrations and effects such as GH peak and blood pressure.

RESULTS

Of 40 participants, 5 children were GH deficient. Peak clonidine concentrations of 0.846 ± 0.288 ng/ml were reached after 1 h. Serum levels declined slowly, with concentrations of 0.701 ± 0.189 ng/ml 210 min post-dose. A large interindividual variation of serum levels was observed. During the procedure, systolic blood pressure dropped by 12.8%, diastolic blood pressure by 19.7% and heart rate by 8.4%. Moderate sedation levels were observed. Concentration-effect modeling showed that the amount of GH available for secretion as determined by previous bursts was an important factor influencing GH response.

CONCLUSION

Clonidine concentrations during the test were higher than necessary according to model-based predictions. A lower clonidine dose may be sufficient and may produce fewer side effects.

Cortisol response to low dose versus standard dose (back-to-back) adrenocorticotrophic stimulation tests in children and young adults with thalassemia major

BACKGROUND

Thalassemia major patients with repeated blood transfusion have high prevalence of endocrinopathies due to iron overload.

MATERIALS AND METHODS

We examined the adrenocortical function in 23 thalassemic patients (10 children and 13 young adults) aged 8-26 years. Serum cortisol and dehydroepiandrosterone sulfate (DHEA-S) concentrations were determined in each subject before blood transfusion both in basal condition and after low dose (LD) (1 μg), followed by standard dose (SD) (250 μg, respectively) with synthetic corticotrophin beta 1-24 ACTH (Synacthen, Ciba). Normal controls were a group of 13 age- and sex-matched normal subjects.

RESULTS

Using a peak total cortisol cutoff level of 550 nmol/L and increments of 200 μg above basal cortisol, adrenal insufficiency (AI) was demonstrated in 8 patients (34.7%) after the LD ACTH and in 2 patients (8.7%) after SD cosyntropin (ACTH) test, but none of the controls. Using a peak total cortisol cutoff level of 420 nmol/L and increments of 200 μg above basal cortisol, AI was demonstrated in 5 patients (21.7%) after the LD ACTH and in 2 patients after SD ACTH test (8.7%), but none of controls. All patients with biochemical AI were asymptomatic with normal serum sodium and potassium concentrations and had no history suggestive of adrenal pathology. The peak cortisol concentrations in thalassemic patients with impaired adrenal function both after 1 μg and 250 μg cosyntropin (294 ± 51 nmol/L and 307 ± 58.6) were significantly lower than those with patients with normal (454 ± 79.7 nmol/L and 546.1 ± 92.2 nmol/L, respectively) and controls (460.2 ± 133.4 nmol/L and 554.3 ± 165.8 nmol/L, respectively). Adolescents and young adults, but not children with thalassaemia, had significantly lower peak cortisol concentration after SD ACTH versus controls. Peak cortisol response to LD ACTH was correlated significantly with peak cortisol response to SD in all patients (r = 0.83, P < 0.0001). In adolescents and young adults with thalassemia, DHEA-S levels before and after LD ACTH stimulation were significantly lower and the cortisol/DHEA-S ratios were significantly higher than the controls.

CONCLUSION

The use of LD ACTH test diagnoses more adrenal abnormalities versus SD ACTH in thalassemic patients. The relatively high prevalence of AI in thalassemic adolescents and young adults necessitates that these patients have to be investigated for AI before major surgery and those with impaired cortisol secretion should receive stress doses of corticosteroids during the stressful event.

Diagnosis and treatment of growth hormone deficiency in adults

The availability of synthetic recombinant human growth hormone (GH) in potentially unlimited quantities since the 1980s has improved understanding of the many nonstatural effects of GH on metabolism, body composition, physical and psychological function, as well as the consequences of GH deficiency in adult life. Adult GH deficiency is now recognized as a distinct if nonspecific syndrome with considerable adverse health consequences. GH replacement therapy in lower doses than those used in children can reverse many of these abnormalities and restore functional capacities toward or even to normal; if dosed appropriately, GH therapy has few adverse effects. Although some doubts remain about possible long-term risks of childhood GH therapy, most registries of adult GH replacement therapy, albeit limited in study size and duration, have not shown an increased incidence of cancers or of cardiovascular morbidity or mortality.

Method-specific serum cortisol responses to the adrenocorticotrophin test: comparison of gas chromatography-mass spectrometry and five automated immunoassays

OBJECTIVE

The serum cortisol response to the adrenocorticotrophin (ACTH) test is known to vary significantly by assay, but lower reference limits (LRL) for this response have not been established by the reference gas chromatography-mass spectrometry (GC-MS) method or modern immunoassays. We aimed to compare the normal cortisol response to ACTH stimulation using GC-MS with five widely used immunoassays.

DESIGN, PATIENTS AND MEASUREMENTS

An ACTH test (250 μg iv ACTH1-24 ) was undertaken in 165 healthy volunteers (age, 20-66 years; 105 women, 24 of whom were taking an oestrogen-containing oral contraceptive pill [OCP]). Serum cortisol was measured using GC-MS, Advia Centaur (Siemens), Architect (Abbott), Modular Analytics E170 (Roche), Immulite 2000 (Siemens) and Access (Beckman) automated immunoassays. The estimated LRL for the 30 min cortisol response to ACTH was derived from the 2·5th percentile of log-transformed concentrations.

RESULTS

The GC-MS-measured cortisol response was normally distributed in males but not females, with no significant gender difference in baseline or post-ACTH cortisol concentration. Immunoassays were positively biased relative to GC-MS, except in samples from women on the OCP, who showed a consistent negative bias. The LRL for cortisol was method-specific [GC-MS: 420 nm; Architect: 430 nm; Centaur: 446 nm; Access 459 nm; Immulite (2000) 474 nm] and, for the E170, also gender-specific (female: 524 nm; male 574 nm). A separate LRL is necessary for women on the OCP.

CONCLUSIONS

Normal cortisol responses to the ACTH test are influenced significantly by assay and oestrogen treatment. We recommend the use of separate reference limits in premenopausal women on the OCP and warn users that cortisol measurements in this subgroup are subject to assay interference.

Lack of sensitivity of the 1-μg low-dose ACTH stimulation test in a paediatric population with suboptimal cortisol responses to insulin-induced hypoglycaemia

CONTEXT

The insulin-tolerance test (ITT) is the gold standard for evaluation of the hypothalamic-pituitary-adrenal (HPA) axis. The low-dose ACTH stimulation test is increasingly used for evaluation of secondary adrenal insufficiency as several studies performed in adults have demonstrated high sensitivity and specificity when compared to the ITT. Whether the ACTH stimulation test demonstrates similar sensitivity in a paediatric and adolescent population compared with the gold standard is unclear.

OBJECTIVE

To compare the sensitivity of the low-dose (1-μg) Synacthen(™) test (LDSST) and the gold-standard ITT in a paediatric and adolescent population.

DESIGN AND PATIENTS

A retrospective review of 42 consecutive LDSSTs in children and adolescents with suboptimal cortisol responses (peak <500 nm) on ITT.

RESULTS

Thirty-one patients (74%) had an adequate cortisol response to low-dose Synacthen(™) (sensitivity 26%). Patients had a higher cortisol increment with the LDSST than ITT (median Δ cortisol 294 vs 168 nm, P < 0.0001) and correspondingly a higher cortisol peak (median peak cortisol 572 vs 396 nm, P < 0.0001). Patients who had a suboptimal peak cortisol both on ITT and on LDSST had a lower baseline cortisol on ITT (median 178 vs 227 nm, P = 0.04). Peak cortisol on ITT was significantly higher in patients who had a subsequent normal LDSST than those that did not (median 417 vs 300 nm, P = 0.0005).

CONCLUSIONS

The 1-μg LDSST lacks sensitivity in detection of secondary adrenal insufficiency in children when compared to the gold-standard ITT.

Testing for growth hormone deficiency in adults: doing without growth hormone-releasing hormone

PURPOSE OF REVIEW

This article summarizes recent advances in testing for growth hormone deficiency (GHD) in adults, focusing on critical appraisal of existing growth hormone (GH) provocative tests as well as newer tests in development.

RECENT FINDINGS

The diagnosis of GHD can be challenging and often requires the use of GH provocative testing. The most widely validated of these is insulin-induced hypoglycemia (ITT), which requires close supervision and has significant contraindications and side-effects. The arginine-growth hormone-releasing hormone (GHRH) test had become widely used as a safe and accurate alternative to the ITT, but GHRH is currently unavailable for clinical use in the USA. On the basis of review of recent literature we recommend that in the absence of GHRH, glucagon stimulation testing should be the preferred alternative to ITT. Several synthetic GH secretagogues that mimic the gastric peptide ghrelin are currently in development and may become available for use in the diagnosis of GHD in the near future. Other GH provocative tests suitable for use in children lack adequate specificity for the diagnosis of GHD in adults.

SUMMARY

Due to the current unavailability of the arginine-GHRH test in the USA, when ITT is contraindicated or impractical we recommend the glucagon stimulation testing as the GH provocative test of choice. There remains a need for a simple, safe and accurate test for the diagnosis of GHD.

Depth and duration of hypoglycaemia achieved during the insulin tolerance test

CONTEXT

The insulin tolerance test (ITT) is the gold standard for assessment of the pituitary adrenal axis but its use is limited because of concerns relating to the risk of hypoglycaemia.

OBJECTIVE

This study examined the depth and duration of hypoglycaemia achieved during the test in a large cohort of patients.

DESIGN

Two hundred and twenty ITTs were performed from 2005 to 2010.

SETTING

A 1200-bed University Teaching Hospital.

PATIENTS

Two hundred and twenty ITTs were carried out in patients with suspected or known pituitary disorders.

INTERVENTIONS

Intravenous insulin was administered to achieve nadir plasma glucose (NPG) of 2.2 mmol/l (39.6 mg/dl). Blood chemistry to show the cortisol and GH response to hypoglycaemic stress was measured.

MAIN OUTCOME MEASURES

Predictors of depth and duration of hypoglycaemia, adverse events and within-subject variability of nadir glucose, peak cortisol and peak GH were studied.

RESULTS

Thirty percent of the cohort achieved a nadir glucose of <2.0 mmol/l (36 mg/dl) that lasted for 60 min or more. The NPG correlated positively with fasting plasma glucose (FPG; r=0:56; P<0.0005), insulin dose (r=0.27; P<0.0005) and weight (r=0.21; P<0.004). The within subject variability of nadir glucose was 15.2%, peak cortisol was 11.7% and peak GH was 6.4%. The factors determining nadir blood glucose were FPG (b=0.56, P<0.0005, 20% contribution) and weight (b=0.14, P<0.05, 2% contribution). The five patients with adverse events had NPG and insulin dose comparable with the rest of the population.

CONCLUSIONS

The hypoglycaemia achieved during the ITT is much lower than the target required. However, adverse events are few and do not relate to the depth of hypoglycaemia.

Hypothalamic-pituitary-adrenal (HPA) axis suppression after treatment with glucocorticoid therapy for childhood acute lymphoblastic leukaemia

BACKGROUND

Glucocorticoids play a major role in the treatment of acute lymphoblastic leukaemia (ALL). However, supraphysiological doses may cause suppression of the hypothalamic-pituitary-adrenal (HPA) axis. HPA axis suppression resulting in reduced cortisol response may cause an impaired stress response and an inadequate host defence against infections, which remains a cause of morbidity and death. The exact occurrence and duration of HPA axis suppression after glucocorticoid therapy for childhood ALL are unclear.

OBJECTIVES

To examine the occurrence and duration of HPA axis suppression after (each cycle of) glucocorticoid therapy for childhood ALL.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (in The Cochrane Library, issue 3, 2010), MEDLINE/PubMed (from 1945 to July 2010) and EMBASE/Ovid (from 1980 to July 2010). In addition, we searched reference lists of relevant articles, conference proceedings and ongoing trial databases.

SELECTION CRITERIA

All study designs, except case reports and patient series with fewer than 10 patients, examining the effect of glucocorticoid therapy for childhood ALL on the HPA axis function.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection. One review author performed the data extraction and 'Risk of bias' assessment, which was checked by another review author.

MAIN RESULTS

We identified seven studies (total number of participants = 189), including one randomised controlled trial (RCT), which assessed the adrenal function. None of the studies assessed the HPA axis at the level of the hypothalamus, pituitary, or both. Due to substantial differences between studies, results could not be pooled. All studies had some methodological limitations. The included studies demonstrated that adrenal insufficiency occurs in nearly all patients in the first days after cessation of glucocorticoid treatment for childhood ALL. The majority of patients recovered within a few weeks, but a small amount of patients had ongoing adrenal insufficiency lasting up to 34 weeks. In the RCT, the occurrence and duration of adrenal insufficiency did not differ between the prednisolone and dexamethasone arms. In one study included in the review it appeared that treatment with fluconazole prolonged the duration of adrenal insufficiency.

AUTHORS' CONCLUSIONS

Based on the available evidence, we conclude that adrenal insufficiency commonly occurs in the first days after cessation of glucocorticoid therapy for childhood ALL, but the exact duration is unclear. Since no data on the level of the hypothalamus and the pituitary were available we cannot make any conclusions regarding those outcomes. Clinicians should consider prescribing glucocorticoid replacement therapy during periods of serious stress in the first weeks after cessation of glucocorticoid therapy for childhood ALL, to reduce the risk of life-threatening complications. However, more high-quality research is needed for evidence-based guidelines for glucocorticoid replacement therapy.Special attention should be paid to patients receiving fluconazole therapy, and perhaps similar antifungal drugs, as this may prolong the duration of adrenal insufficiency.

Prevalence of hypothalamic-pituitary-adrenal axis suppression in children treated for asthma with inhaled corticosteroid

OBJECTIVE

To determine the prevalence of hypothalamic-pituitary-adrenal (HPA) axis suppression in asthmatic children on inhaled corticosteroids (ICS).

METHODS

Clinical and demographic variables were recorded on preconstructed, standardized forms. HPA axis suppression was measured by morning serum cortisol levels and confirmed by low-dose adrenocorticotropic hormone stimulation testing.

RESULTS

In total, 214 children participated. Twenty children (9.3%, 95% CI 5.3% to 13.4%) had HPA axis suppression. Odds of HPA axis suppression increased with ICS dose (OR 1.005, 95% CI 1.003 to 1.009, P<0.001). All children with HPA axis suppression were on a medium or lower dose of ICS for their age (200 μg/day to 500 μg/day). HPA axis suppression was not predicted by drug type, dose duration, concomitant use of long-acting beta-agonist or nasal steroid, or clinical features.

CONCLUSION

Laboratory evidence of HPA axis suppression exists in children taking ICS for asthma. Children should be regularly screened for the presence of HPA axis suppression when treated with high-dose ICS (>500 μg/day). Consideration should be given to screening children on medium-dose ICS.

Quantifying the risk of hypoglycaemia in children undergoing the glucagon stimulation test

OBJECTIVE

The low-dose (15-30 μg/kg) glucagon stimulation test (GST) is assumed to be associated with fewer episodes of low blood glucose (BG). We aimed to quantify the risk of hypoglycaemia in children undergoing the low-dose GST to evaluate their growth hormone status.

DESIGN AND PATIENTS

Blood glucose fluctuations during the GST in 80 children (median age 8·7 years, 45 boys, 66 prepubertal) who received a median 20·5 μg/kg of intramuscular glucagon were reviewed.

MEASUREMENTS

The rate of (i) hypoglycaemia (BG < 3·3 mm), (ii) falling BG trend at the end of the GST (lower BG at 180 min than at 120 min), (iii) hypoglycaemia and falling BG trend at the end of the GST, and (iv) at-risk patients (those with at least one of the three risks measures).

RESULTS

Twenty-seven of the 80 children had hypoglycaemia during the GST. Twenty-six children showed a falling BG trend at the end of the GST and were significantly younger than the other 54 children with a rising BG trend [5·1 (3·1-10·4) years vs 9·6 (5·4-11·8) years, P = 0·02]. Eight children had both a falling BG trend and hypoglycaemia at end of the test. Forty-four children were at-risk patients, and the odds ratio of being an at-risk patient in those <8 years old was 2·63 (95% CI 1·06-6·57, P = 0·04).

CONCLUSIONS

Hypoglycaemia is not uncommon during the low-dose GST. Young children, especially those <8 years old, are particularly at risk. BG monitoring should be considered essential from a safety perspective.

Growth hormone: the expansion of available products and indications

Growth hormone is a widely used hormone. This article describes its historical use, current indications and studies for possible future uses.

Duration of adrenal insufficiency during treatment for childhood acute lymphoblastic leukemia

Children with acute lymphoblastic leukemia (ALL) recive high doses of glucocorticosteroid as part of their treatment. This may lead to suppression of the hypothalamic-pituitary-adrenal axis, acute adrenal insufficiency, and ultimately to life-threatening conditions. This study explores the adrenal function in 96 children with ALL treated according to common protocols. After cessation of induction glucocorticosteroid therapy, they received hydrocortisone substitution therapy (10 mg/m/24 h) until an adrenocorticotropic hormone test (250 μg tetracosatide) showed a sufficient adrenal response [plasma (p)-cortisol ≥500 nM]. At the first adrenocorticotropic hormone test, 67% of the patients had adrenal insufficiency. When including these patients in a multivariate model, not adjusting for risk factors, the mean elapsed time between end of induction therapy and adrenal sufficiency was 8.5 months (95% confidence interval: 6.3;10.7). Low 0-minute p-cortisol (P=0.02) and low rise in p-cortisol (P<0.0001) at first test caused a longer time of adrenal insufficiency. In addition, patients with B-cell precursor leukemia reached adrenal sufficiency later than those with T-cell leukemia (P=0.067). As adrenal insufficiency is frequent in children treated for ALL and as they often experience infections and other stressors, the adrenal response should be determined and hydrocortisone substitution therapy should be considered during such episodes in patients with adrenal insufficiency.

Does plasma IGF-BP3 measurement contribute to the diagnosis of growth hormone deficiency in children?

OBJECTIVE

To audit the contribution of plasma IGF-PB3 measurement to the diagnosis of growth hormone deficiency (GHD) in children.

POPULATION AND METHODS

Retrospective case study including boys and girls aged 0 to 18 years who attended our paediatric endocrinology clinic for short stature and/or post-irradiation follow-up, and had at least one GH provocative testing. Children with hypothyroidism, Laron or Kowarski syndromes, severe malnutrition, chronic renal failure and liver failure were excluded.

RESULTS

Fifty-eight children were enrolled and grouped as GHD [+] (19 cases) and GDH [-] (39 cases). IGF-I and IGF-BP3 assay was carried out in 88% and 62% cases respectively, both groups were comparable for age, sex, BMI, target height, pubertal stage and bone age. There was a significant difference in peak GH between GDH [-] and GHD [+] groups (41.8 mUI/L ± 21.7 versus 11.5 ± 5.9 mUI/L, P<0.00001, respectively). No difference was found between groups with regards to IGF-I Z-scores and IGF-BP3 Z-scores. There was, however, a positive correlation between IGF-I Z-scores and IGF-BP3 Z-scores (r=0.50; P<0.0016). IGF-BP3 measurement could not differentiate between GHD [+] and GHD [-] groups.

CONCLUSIONS

Measurement of plasma IGF-BP3 level contributes poorly to the diagnosis of GHD. We do not recommend it in routine use.

The low-dose ACTH test does not identify mild insufficiency of the hypothalamnic-pituitary-adrenal axis in children with inadequate stress response

OBJECTIVE

To investigate retrospectively the sensitivity of published cortisol cut-off points of the low-dose ACTH test (LDAT) in children with proven mild hypothalamic-pituitary-adrenal (HPA) axis insufficiency.

PATIENTS AND METHODS

The HPA axis of 11 pediatric patients (age range: 5.5-14.5 yr) with established mild HPA axis insufficiency was reinvestigated with the LDAT. The sensitivity of the LDAT was calculated on the basis of published stimulated cortisol cut-off points.

RESULTS

The LDAT showed both a significantly higher cortisol peak and a greater cortisol rise compared with the ITT (both P < 0.01). The LDAT yielded a low sensitivity of 9-55% using published cortisol cut-off points as references.

CONCLUSION

Using published cortisol cut-off points, the LDAT showed a poor sensitivity to detect mild HPA axis insufficiency. We cannot recommend the use of the LDAT as a screening test of HPA axis impairment in such children.

Somatotropin in the treatment of growth hormone deficiency and Turner syndrome in pediatric patients: a review

Growth hormone (GH), also known as somatotropin, is a peptide hormone that is synthesized and secreted by the somatotrophs of the anterior pituitary gland. The main action of GH is to stimulate linear growth in children; however, it also fosters a healthy body composition by increasing muscle and reducing fat mass, maintains normal blood glucose levels, and promotes a favorable lipid profile. This article provides an overview of the normal pathophysiology of GH production and action. We discuss the history of GH therapy and the development of the current formulation of recombinant human GH given as daily subcutaneous injections. This paper reviews two of the longest standing FDA-approved indications for GH treatment, GH deficiency and Turner syndrome. We will highlight the pathogenesis of these disorders, including presentations, presumed mechanism(s) for the associated short stature, and diagnostic criteria, with a review of stimulation test benefits and pitfalls. This review also includes current recommendations for GH therapy to help maximize final height in these children, as well as data demonstrating the efficacy and safety of GH treatment in these populations.

Severe hyponatremia due to ACTH insufficiency in a 14 year-old girl with growth hormone deficiency

SIADH-like hyponatremia as the presenting manifestation of ACTH deficiency is rare in childhood. Here we report a 14 year-old girl who, after 8 years of GH replacement and subsequent treatment for subclinical secondary hypothyroidism, presented with confusion and disorientation due to severe hyponatremia. When her pituitary axis was re-assessed, she was diagnosed as having ACTH deficiency associated with multiple pituitary hormone deficiencies (MPHD) (including GH, FSH, LH, and subclinical TSH deficiencies). She responded poorly to treatment with only hypertonic fluid, but improved after addition of hydrocortisone replacement. The purpose of this paper is to emphasize the importance of suspecting ACTH insufficiency in children with GH deficiency if hyponatremia develops.

Adrenal function testing in pediatric cancer survivors

BACKGROUND

Central adrenal insufficiency is observed after cranial radiation therapy for cancer. Screening at risk patients is recommended, but the best screening strategy is unknown.

METHODS

A retrospective review of pediatric cancer survivors who underwent hypothalamic/pituitary/adrenal axis testing was conducted. Data included: cancer diagnosis, radiotherapy dose, other endocrinopathies, and adrenal function testing. Adrenal testing included sequential low-dose corticotropin test (LDCT) and standard-dose corticotropin test (SDCT). 8 a.m. serum cortisol levels were compared to LDCT results. LDCT results were compared by radiotheroapy dose and according to the presence of endocrine comorbidities.

RESULTS

Seventy-eight subjects (56% male, mean age at diagnosis 6.5 years) underwent testing. 67.9% had been treated with radiotherapy to the hypothalamus/pituitary. Mean time to diagnosis of adrenal insufficiency was 6.8 years after cancer diagnosis. Adequate adrenal function was found in 65% of patients by LDCT and 89% by SDCT. Only 21% of patients had basal serum cortisols collected at 8 a.m. Agreement between 8 a.m. baseline cortisol and LDCT was fair. Agreement between random baseline cortisol and LDCT was poor. Prevalence of central adrenal insufficiency diagnosed by LDCT increased with radiotherapy dose (8% for 10-19.9 Gy; 83% for >or=40 Gy) and the number of endocrine comorbidities.

CONCLUSIONS

In pediatric cancer survivors, central adrenal insufficiency was common even in patients receiving <40 Gy to the hypothalamus/pituitary. We recommend use of LDCT, not 8 a.m. serum cortisol to screen patients who received >30 Gy of radiotherapy and those with other central endocrinopathies.

Repeatability of the low-dose ACTH test in asthmatic children on inhaled corticosteroids

AIM

To assess the repeatability of low-dose Synacthen test (LDST) in asthmatic children receiving high-dose fluticasone propionate (FP).

METHODS

Low-dose Synacthen test was performed on 18 children with stable chronic asthma treated with FP at a constant daily dose of > or =500 microg and repeated 1 month later. Repeatability was assessed using the Kappa statistic for categorical variables.

RESULTS

Fifteen patients had consistent results (either two normal or two abnormal responses) and three patients had inconsistent results (one normal and one abnormal response). The Kappa statistic was 0.56 indicating fair to good agreement between the tests.

CONCLUSION

The results of adrenal function testing in patients on inhaled steroids can have major implications for patient management, making it important to use a test with excellent repeatability. The LDST conducted using our protocol does not fulfil this criterion.

Growth hormone: the expansion of available products and indications

Growth hormone is a widely used hormone. This article describes its historical use, current indications and studies for possible future uses.

Clinical review: Is lack of recombinant growth hormone (GH)-releasing hormone in the United States a setback or time to consider glucagon testing for adult GH deficiency?

CONTEXT

The use of the combined GHRH and arginine (GHRH-ARG) test has gained increasing acceptance in the United States as a reliable alternative test to the insulin tolerance test (ITT) for diagnosing adult GH deficiency (GHD). In July 2008, the only manufacturer of recombinant GHRH in the United States, EMD Serono, Inc., announced the discontinuation of Geref, thus raising the question of which reliable alternative GH stimulation test should practicing endocrinologists be considering in place of the GHRH-ARG test. In this article, we review the existing published data and consensus guidelines and provide recommendations for alternative stimulation tests to the GHRH-ARG test.

EVIDENCE ACQUISITION

The major source of data acquisition included PubMed search strategies and personal experience of the authors from clinical experience.

EVIDENCE SYNTHESIS

Previous consensus guidelines and previous data assessing the reliability and discriminatory value of the GHRH-ARG, glucagon, ARG, and GH secretagogues on assessing GH reserve are discussed. Our recommendations for performing the glucagon stimulation test, potential drawbacks in conducting this test, and caveats in interpreting this test are also discussed.

CONCLUSIONS

The ITT should remain the test of choice in diagnosing adult GHD. However, when the ITT is not desirable and recombinant GHRH remains unavailable in the United States, we recommend the alternative to the GHRH-ARG test to be the glucagon stimulation test, based on its reliability and availability. Nevertheless, further studies into alternative GH stimulation tests that are available in the United States, comparable, and simpler to perform than the ITT in diagnosing adult GHD are still needed.