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

Reliability of Agreement between Insulin, Clonidine, and Glucagon Stimulation Tests for the Diagnosis of Growth Hormone Deficiency in Children: A Retrospective Cohort Study

Growth hormone (GH) deficiency (GHD) is a rare disorder. The diagnosis of GHD requires a combination of two provocative GH tests. This study aimed to find agreement between commonly used medications to determine which combined tests have high reliability of agreement. This retrospective cohort included 201 children who underwent GH provocation testing from January 2012 to December 2022. The insulin tolerance test (ITT) with the clonidine stimulation test (CST) or glucagon stimulation test (GST) with the CST were performed. We calculated Cohen's kappa to determine the agreement between the test medications by considering the post-stimulation peak GH level with a cut-off value of 10 ng/mL as the primary outcome. A total of 151 patients underwent the two provocative tests and were included in the analysis. Of these patients, 119 underwent the ITT and CST and 54 (45.3%) were diagnosed with GHD. However, 32 patients underwent the GST and CST and 18 (56.2%) were diagnosed with GHD. The kappa value for ITT and CST was 0.258 (25.8%), indicating fair agreement between clonidine and insulin (p = 0.005). However, the kappa value for CST and GST was 0.178 (17.8%), representing slight agreement. The correlation coefficient revealed a very strong relationship between ITT and CST. Clonidine has fair agreement and a very strong correlation coefficient with ITT when used to diagnose GHD in children. Among the commonly used pharmacological tests for GH provocation in our unit, the CST was considered the best pharmacological test in terms of safety and reduced parental anxiety.

Performance of glucagon stimulation test in diagnosing central adrenal insufficiency in children when utilising the Roche Elecsys® cortisol II assay: a pilot study

OBJECTIVES

The glucagon stimulation test (GST) is used for the simultaneous assessment of central adrenal insufficiency (CAI) and growth hormone deficiency. The new Roche cortisol II (C II) assay was recently introduced, confounding interpretation of the GST. The performance of the GST in diagnosing central adrenal insufficiency (CAI), utilising the C II assay, was therefore compared with that of the overnight metyrapone test (ONMTPT).

METHODS

A diagnostic accuracy study was performed by retrospectively analysing folders and laboratory records of 25 children and adolescents investigated for hypopituitarism with the GST and the ONMTPT between September 2016 and December 2019. The peak serum cortisol (C) of the GST, the post-metyrapone serum 11-deoxycortisol and adrenocorticotropin levels of the ONMTPT were recorded. Diagnostic performance of the GST at a previously suggested cut-off of 374 nmol/L was evaluated.

RESULTS

Seventeen boys and 8 girls, aged 1.7-16.3 years (median 7.3 years) were identified. The sensitivity of the post-GST C-level at 374 nmol/L was 0.40 (95% confidence interval [CI] 0.17-0.69), specificity 0.64 (95% CI 0.39-0.84), positive predictive value 0.44 (95% CI 0.19-0.73), negative predictive value 0.60 (95% CI 0.36-0.80), accuracy 0.54 (95% CI 0.35-0.72), positive likelihood ratio (+LR) 0.93 (95% CI 0.49-1.77) and negative LR 1.12 (95% CI 0.40-3.15). The area under the receiver of operating characteristics (ROC) curve was 0.379 (95% CI 0.142-0.615).

CONCLUSIONS

This study suggests that the GST at any C II cut-off cannot replace the ONMTPT as a diagnostic test for CAI in children. Findings should be confirmed in a larger study.

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.

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.

Adding Glucagon-Stimulated GH Testing to the Diagnostic Fast Increases the Detection of GH-Sufficient Children

BACKGROUND/AIMS

The evaluation of children with unexplained hypoglycemia may include a diagnostic fast. However, low growth hormone (GH) concentration during hypoglycemia is not specific to GH deficiency (GHD). The aim of this study was to determine if serial GH measurement following glucagon administration, in the setting of a diagnostic fast, would increase the number of children identified as not having GHD.

METHODS

We conducted a retrospective chart review of children who had serial GH measurements performed after glucagon administration at the end of a diagnostic fast. Glucagon was administered at the end of the fasting study, and GH was measured every 30 min for 210 min.

RESULTS

Of the 29 children in this series, only 3 (10%) had GH concentrations >7 ng/ml at the end of the fast, which increased by 16 (55%) after serial GH testing. The percentages of samples with GH concentrations >7 ng/ml were: 10% at baseline, and 25, 39, 41, 41, 33, 43, and 0% every 30 min thereafter.

CONCLUSION

Additional GH measurements after glucagon administration following a diagnostic fast can improve the identification of children without GHD and thereby save them unnecessary GH stimulation testing and potential GH treatment.

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.