Pharmacological and physiological growth hormone stimulation tests to predict successful GH therapy in children

Evolving growth hormone deficiency: proof of concept

Introduction

We present the evolution of GHD in adolescent males with persistent growth failure, in whom the diagnosis was established after a second GH stimulation test (GST).

Methods

We performed a retrospective chart review of children who presented for short stature (height less < 2SD for mean/mid-parental height) and/or growth failure (sustained growth velocity < 0 SD) to pediatric endocrinology at Mount Sinai Kravis Children's Hospital, New York and who had 2 GSTs. Data collected from electronic medical records were analyzed using SPSS v28.0.

Results

Of 53 patients included, 42 were males. Average GH peak on initial GST was 15.48 ± 4.92 ng/ml, at 10.07 ± 2.65 years, mean height -1.68 ± 0.56SD(28% had <2SD), IGF-1 -1.00 ± 0.88SD. After 2.23 ± 1.22 years, at 12.04 ± 2.41years, height SDs decreased to -1.82 ± 0.63SD and IGF-1 was -1.08 ± 0.84SD. At repeat GST, average GH peak was 7.59 ± 2.12 ng/dL, with 36% ≤7 ng/dl and 32% in puberty. 12 males reached adult height of 0.08 ± 0.69 SD with a mean height gain of 1.83 ± 0.56SD(p<0.005), IGF-1 of -1.15 ± 0.81SD after 4.64 ± 1.4 years of GH.

Conclusion

We offer evidence for Evolving Growth Hormone Deficiency (EGHD) through repeat GST in children with persistent growth slowdown, even with pubertal progression; emphasizing the need for careful longitudinal follow-up to make accurate diagnosis.

Growth Hormone Stimulation Testing: To Test or Not to Test? That Is One of the Questions

The evaluation of children with short stature includes monitoring over a prolonged period to establish a growth pattern as well as the exclusion of chronic medical conditions that affect growth. After a period of monitoring, evaluation, and screening, growth hormone stimulation testing is considered when the diagnosis of growth hormone deficiency (GHD) is entertained. Though flawed, growth hormone stimulation tests remain part of the comprehensive evaluation of growth and are essential for the diagnosis of growth hormone (GH) deficiency. Variables including testing length, growth hormone assay and diagnostic cut off affect results. Beyond the intrinsic issues of testing, results of GH stimulation testing can be influenced by patient characteristics. Various factors including age, gender, puberty, nutritional status and body weight modulate the secretion of GH.

Provocative growth hormone testing in children: how did we get here and where do we go now?

OBJECTIVES

Provocative growth hormone (GH) tests are widely used for diagnosing pediatric GH deficiency (GHD). A thorough understanding of the evidence behind commonly used interpretations and the limitations of these tests is important for improving clinical practice.

CONTENT

To place current practice into a historical context, the supporting evidence behind the use of provocative GH tests is presented. By reviewing GH measurement techniques and examining the early data supporting the most common tests and later studies that compared provocative agents to establish reference ranges, the low sensitivity and specificity of these tests become readily apparent. Studies that assess the effects of patient factors, such as obesity and sex steroids, on GH testing further bring the appropriateness of commonly used cutoffs for diagnosing GHD into question.

SUMMARY AND OUTLOOK

Despite the widely recognized poor performance of provocative GH tests in distinguishing GH sufficiency from deficiency, limited progress has been made in improving them. New diagnostic modalities are needed, but until they become available, clinicians can improve the clinical application of provocative GH tests by taking into account the multiple factors that influence their results.

Association Between Hemoglobin and Growth Hormone Peak in Chinese Children and Adolescents with Short Stature: A Cross-Sectional Study

Objective

This research aimed to investigate the relationship between hemoglobin (Hb) and growth hormone (GH) peak in children and adolescents with short stature.

Design

This cross-sectional study included a total of 787 children and adolescents with short stature. Anthropometric and biochemical indicators were measured at baseline. All patients underwent GH provocation tests with L-dopa and insulin to assess GH peak levels.

Results

The univariate analysis results showed that Hb was positively associated with GH peak (β 0.07, P=0.001). Furthermore, a non-linear relationship was detected between Hb and GH peaks through smooth curve fitting, and the inflection point was 123 g/L after multivariate piecewise linear regression analysis. GH peak increased with Hb elevation when the Hb level was greater than 123 g/L (β 0.08, 95% CI 0.01, 0.14; P=0.0207).

Conclusion

In children and adolescents with short stature, we found GH peak was positively associated with the Hb level when the Hb level reached the inflection point.

How to interpret IGF-1 and growth hormone stimulation tests

You are seeing an 11-year-old boy in a general paediatric clinic referred with short stature. His height is below the 0.4th centile. The mid-parental height is on 50th centile. Baseline investigations, including renal and liver function, coeliac screen and thyroid function tests are normal. You have a suspicion of growth hormone deficiency. Should you check an insulin-like growth factor-1 level or proceed with a growth hormone provocation test? The current paper will aim to give an overview of these tests and factors to consider when interpreting the results.

Diagnosis and Treatment of Growth Hormone Deficiency: A Position Statement from Korean Endocrine Society and Korean Society of Pediatric Endocrinology

Growth hormone (GH) deficiency is caused by congenital or acquired causes and occurs in childhood or adulthood. GH replacement therapy brings benefits to body composition, exercise capacity, skeletal health, cardiovascular outcomes, and quality of life. Before initiating GH replacement, GH deficiency should be confirmed through proper stimulation tests, and in cases with proven genetic causes or structural lesions, repeated GH stimulation testing is not necessary. The dosing regimen of GH replacement therapy should be individualized, with the goal of minimizing side effects and maximizing clinical improvements. The Korean Endocrine Society and the Korean Society of Pediatric Endocrinology have developed a position statement on the diagnosis and treatment of GH deficiency. This position statement is based on a systematic review of evidence and expert opinions.

Peak Growth Hormone Response to Combined Stimulation Test in 315 Children and Correlations with Metabolic Parameters

BACKGROUND/AIMS

Studies are lacking regarding the timing of peak growth hormone (PGH) response. We aim to elucidate the timing of PGH response to arginine and levodopa (A-LD) and evaluate the influence of body mass index (BMI) and other metabolic parameters on PGH.

METHODS

During growth hormone (GH) stimulation testing (ST) with A-LD, serum GH was measured at baseline and every 30 min up to 180 min. The PGH cut-off was defined as &amp;#x3c;10 ng/mL. IGF-1, IGF BP3, BMI, and metabolic parameters were obtained in a fasting state at baseline.

RESULTS

In the 315 tested children, stimulated PGH levels occurred at or before 120 min in 97.8% and at 180 min in 2.2%. GH area under the curve (AUC) positively correlated with PGH in all patients and with IGF-1 in pubertal males and females. BMI negatively correlated with PGH in all subjects. GH AUC negatively correlated with HOMA-IR and total cholesterol.

CONCLUSION

We propose termination of the GH ST with A-LD at 120 min since omission of GH measurement at 180 min did not alter the diagnosis of GH deficiency based on a cut-off of &amp;#x3c; 10 ng/mL. BMI should be considered in the interpretation of GH ST with A-LD. The relationships between GH AUC and metabolic parameters need further study.

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.

Height gain at adult-height age in 184 short patients treated with growth hormone from prepubertal age to near adult-height age is not related to GH secretory status at GH therapy onset

BACKGROUND

GH release after stimuli classifies short children as severe idiopathic isolated GH deficiency (IIGHD), mild IIGHD, dissociated GH release (DGHR) and normal GH release (NGHR) and anthropometric birth data as adequate for gestational age (AGA) or small for gestational age (SGA). GH release after stimuli classifies AGA patients as IIGHD or as idiopathic short stature (ISS).

AIM

To compare height gain induced by GH therapy (31.8 ± 3.5 µg/kg/day, 7.7 ± 1.6 years) started at prepubertal age and stopped at near adult-height age.

METHODS

A retrospective longitudinal multicenter study including 184 short patients classified as severe IIGHD n = 25, mild IIGHD n = 75, DGHR n = 55 and NGHR n = 29; or as IIGHD n = 78, ISS n = 57 and SGA n = 49. Height gain was evaluated throughout GH therapy and at adult-height age.

RESULTS

Height-SDS gain at adult-height age was similar among severe IIGHD (1.8 ± 0.8 SDS), mild IIGHD (1.6 ± 0.6 SDS), DGHR (1.7 ± 0.7 SDS) and NGHR (1.6 ± 0.7 SDS), or among IIGHD (1.7 ± 0.7 SDS), ISS (1.7 ± 0.6 SDS) and SGA (1.6 ± 0.8 SD).

CONCLUSION

GH-release stimuli are of little help for deciding on GH therapy in the clinical management of prepubertal children with IIGHD, ISS or SGA.

Diagnosis of growth hormone deficiency in childhood

PURPOSE OF REVIEW

The diagnosis of growth hormone deficiency (GHD) in childhood is challenging, in large part because of the lack of a true gold standard and the relatively poor performance of available diagnostic testing. This review discusses the recent literature on this topic.

RECENT FINDINGS

Auxology and clinical judgment remain the foundation for the diagnosis of GHD. Provocative growth hormone testing is poorly reproducible, dependent on factors such as body composition and pubertal status, and further limited by significant variability among commercially available growth hormone assays. Measurement of insulin-like growth factor I and insulin-like growth factor-binding protein 3 is not diagnostically useful in isolation but is helpful in combination with other diagnostic measures. Neuroimaging is also useful to inform diagnosis, as pituitary abnormalities suggest a higher likelihood of GHD persisting into adulthood. Although genetic testing is not routinely performed in the diagnosis of GHD at the present time, multiple recent reports raise the possibility that it may play a more important role in diagnosing GHD in the future.

SUMMARY

Beyond physicians' integrated assessment of auxology, clinical presentation, and bone age, current tools to diagnose GHD are suboptimal. Recent literature emphasizes the need to reappraise our current practice and to consider new tools for diagnosis.