Brain Magnetic Resonance Imaging as First-Line Investigation for Growth Hormone Deficiency Diagnosis in Early Childhood

Diagnosis and management of congenital hypopituitarism in children

Hypopituitarism (or pituitary deficiency) is a rare disease with an estimated prevalence of between 1/16,000 and 1/26,000 individuals, defined by insufficient production of one or several anterior pituitary hormones (growth hormone [GH], thyroid-stimulating hormone [TSH], adrenocorticotropic hormone [ACTH], luteinizing hormone [LH], follicle-stimulating hormone [FSH], prolactin), in association or not with diabetes insipidus (antidiuretic hormone [ADH] deficiency). While in adults hypopituitarism is mostly an acquired disease (tumors, irradiation), in children it is most often a congenital condition, due to abnormal pituitary development. Clinical symptoms vary considerably from isolated to combined deficiencies and between syndromic and non-syndromic forms. Early signs are non-specific but should not be overlooked. Diagnosis is based on a combination of clinical, laboratory (testing of all hormonal axes), imaging (brain magnetic resonance imaging [MRI] with thin slices centered on the hypothalamic-pituitary region), and genetic (next-generation sequencing of genes involved in pituitary development, array-based comparative genomic hybridization, and/or genomic analysis) findings. Early brain MRI is crucial in neonates or in cases of severe hormone deficiency for differential diagnosis and to inform syndrome workup. This article presents recommendations for hormone replacement therapy for each of the respective deficient axes. Lifelong follow-up with an endocrinologist is required, including in adulthood, with multidisciplinary management for patients with syndromic forms or comorbidities. Treatment objectives include alleviating symptoms, preventing comorbidities and acute complications, and optimal social and educational integration.

Clinical, radiological, and molecular diagnosis of congenital pituitary diseases causing short stature

Short stature in children can be caused by congenital pituitary disorders involving at least one form of growth hormone deficiency. Clinical and radiological evaluations of the index case and family history assessments are essential to guide genetic diagnostic testing and interpret results. The first-line approach is panel testing of genes involved in pituitary development with variants known to be pathogenic in this context. It identifies a genetic cause in less than 10% of cases, however. Whole-exome and whole-genome sequencing techniques may provide original information but also raise new questions regarding the pathophysiological role of identified variants. These new tools can make genetic counselling more complex. The role of clinicians in these interpretations is therefore important. © 2022 French Society of Pediatrics. Published by Elsevier Masson SAS. All rights reserved.

Diagnosis of GH Deficiency Without GH Stimulation Tests

Growth hormone deficiency (GHD) is the most commonly affected pituitary hormone in childhood with a prevalence of 1 in 4000-10000 live births. GH stimulation testing (GHST) is commonly used in the diagnostic workup of GHD. However, GHD can be diagnosed in some clinical conditions without the need of GHST. The diagnosis of GHD in newborns does not require stimulation testing. Likewise infants/children with delayed growth and/or short stature associated with neuroradiological abnormalities and one or more additional pituitary hormone deficiencies may not need GHST. This review summarizes the current evidence on the diagnosis of GHD without stimulation tests.

Thyroid function in children with short stature accompanied by isolated pituitary hypoplasia

PURPOSE

Few studies have focused on thyroid function in children with isolated pituitary hypoplasia (IPH). The purpose of this study was to investigate thyroid function in children with short stature accompanied by IPH and evaluate the values of thyroid function for the diagnosis of IPH.

METHODS

This was a retrospective observational study. A total of 100 children with short stature accompanied by IPH were enrolled. Among them, 68 children presenting with isolated growth hormone deficiency (IGHD) were chosen as the IPH group. Sixty-eight age-matched and sex-matched IGHD children without pituitary abnormalities were chosen as the control group. Clinical, hormonal, and imaging parameters were analyzed. The diagnostic value of thyroid function for IGHD children with IPH was evaluated.

RESULTS

Children in the IPH group had significantly lower height standard deviation score (HSDS), HSDS-target height standard deviation score (THSDS), free thyroxine (FT4), insulin-like growth factor-1 standard deviation score (IGF-1SDS), and pituitary height than the control subjects (p = 0.027, p = 0.033, p < 0.001, p = 0.03, and p < 0.001, respectively). The value of the area under the curve (AUC) was 0.701 (95% CI 0.614-0.788, p < 0.001) when the cut-off value for FT4 was ≤ 16.43 pmol/L and the sensitivity and specificity were 72.1 and 61.8%, respectively. FT4 levels were positively correlated with FT3, GH peak, and IGF-1 SDS levels in all children with short stature accompanied by IPH (p < 0.001, p = 0.009, and p = 0.01, respectively).

CONCLUSION

IGHD children with IPH had lower FT4 levels than IGHD children without pituitary abnormalities. FT4 levels may have diagnostic value for IGHD children with IPH.

Questioning the Value of Brain Magnetic Resonance Imaging in the Evaluation of Children with Isolated Growth Hormone Deficiency

BACKGROUND

Isolated growth hormone deficiency (IGHD) is a relatively common disorder. Current diagnostic protocol requires a brain magnetic resonance imaging (MRI) study of the hypothalamus and the hypophysis to determine the cause after establishment of the diagnosis. This study aimed to examine the yield of brain MRI in the evaluation of children with IGHD and to define clinical and laboratory parameters that justify its performance.

METHODS

A retrospective chart review of all children (<18 years) diagnosed with IGHD was conducted at 3 pediatric endocrinology units between 2008 and 2018.

RESULTS

The study included 192 children (107 boys) with confirmed IGHD. The mean age ± standard deviation (SD) at diagnosis was 8.2 ± 3.7 years (median 8.5 years, range 0.8-15.9). The mean height SD score (SDS) at diagnosis was -2.25 ± 0.73. The mean height deficit SDS (defined as the difference between height SDS at diagnosis and mid-parental height SDS) was -1.7 ± 0.9. Fifteen children (7.8%) had pathological MRI findings. No space-occupying lesion was detected. Children with pathological MRIs had greater height deficit SDS and lower peak growth hormone levels on provocative tests compared to children with normal MRIs: -2.3 ± 1.2 vs. -1.6 ± 0.8 (p = 0.02) and 4.4 ± 1.9 vs. 5.7 ± 1.3 (p = 0.01), respectively.

CONCLUSION

Our preliminary data indicate that most brain MRIs performed for routine evaluation of children with IGHD are not essential for determining cause. Further studies with larger cohorts are needed in order to validate this proposed revision of current protocols.

Brain MRIs may be of low value in most children diagnosed with isolated growth hormone deficiency

OBJECTIVES

Brain MRIs are considered essential in the evaluation of children diagnosed with growth hormone deficiency (GHD), but there is uncertainty about the appropriate cut-off for diagnosis of GHD and little data about the yield of significant abnormal findings in patients with peak growth hormone (GH) of 7-10 ng/mL. We aimed to assess the frequency of pathogenic MRIs and associated risk factors in relation to peak GH concentrations.

METHODS

In this retrospective multicenter study, charts of patients diagnosed with GHD who subsequently had a brain MRI were reviewed. MRIs findings were categorized as normal, incidental, of uncertain significance, or pathogenic (pituitary hypoplasia, small stalk and/or ectopic posterior pituitary and tumors). Charges for brain MRIs and sedation were collected.

RESULTS

In 499 patients, 68.1% had normal MRIs, 18.2% had incidental findings, 6.6% had uncertain findings, and 7.0% had pathogenic MRIs. Those with peak GH<3 ng/mL had the highest frequency of pathogenic MRIs (23%). Only three of 194 patients (1.5%) with peak GH 7-10 ng/mL had pathogenic MRIs, none of which altered management. Two patients (0.4%) with central hypothyroidism and peak GH<4 ng/mL had craniopharyngioma.

CONCLUSIONS

Pathogenic MRIs were uncommon in patients diagnosed with GHD except in the group with peak GH<3 ng/mL. There was a high frequency of incidental findings which often resulted in referrals to neurosurgery and repeat MRIs. Given the high cost of brain MRIs, their routine use in patients diagnosed with isolated GHD, especially patients with peak GH of 7-10 ng/mL, should be reconsidered.

Growth hormone deficiency and replacement in children

Growth hormone deficiency (GHD) is a rare but treatable cause of short stature. The diagnosis requires a careful evaluation of clinical history, physical examination and appropriate interpretation of longitudinal growth, with specific features for each period of life. Other clinical findings, in addition to growth failure, may be present and can be related to the etiology and to associated hormone deficiencies. Despite more than 50 years since the first reports of provocative tests of growth hormone (GH) secretion for the diagnosis of GHD, the interpretation of the results remains a matter of debate. When GHD is confirmed, GH treatment is recommended. Treatment is effective and safe, but requires daily injections during many years, which can affect adherence. At the end of longitudinal growth, during the transition phase, it might be necessary to re-evaluate GH secretion. This review summarizes and updates the recent information related to GHD in children, as well the recommendations for treatment.

Prevalence of brain MRI findings in children with nonacquired growth hormone deficiency: a systematic review and meta-analysis

PURPOSE

To verify and integrate the prevalence and phenotype of abnormalities in the sellar region in patients with growth hormone deficiency (GHD) using MRI data.

METHODS

We searched PubMed and EMBASE up to December 14, 2020. The inclusion criteria were as follows: (1) pediatric patients diagnosed with nonacquired GHD and (2) detailed data sufficient to assess the proportion of sellar and parasellar abnormalities on brain MRI scans. Finally, thirty-two studies with 39,060 children (mean or median age, 3.4-14.1 years) were included. The number and type of MRI findings from all included studies were pooled by two authors. The heterogeneity across studies was evaluated with the Q test or the inconsistency index (I²) statistic. Subgroup analyses were performed according to the type of GHD (isolated GHD [IGHD] vs. multiple pituitary hormone deficiency [MPHD]), MRI magnet, geographical region, and cutoff serum growth hormone (GH) level.

RESULTS

The pooled proportion of sellar and parasellar abnormalities was 58.0% (95% CI, 47.1-68.6%; I², 98.2%). The MPHD group showed a higher proportion of sellar and parasellar abnormalities and pituitary stalk interruption syndrome than the IGHD group (91.4% vs. 40.1%, P<0.001; 65.3% vs. 20.1%, P<0.001). The patients in studies with low peak GH levels on stimulation tests were more associated with severe MR abnormalities (cutoff GH ≤ 5 μg/l vs. cutoff GH = 10 μg/l; 72.8 % vs. 38.0%; P<0.001).

CONCLUSION

The types and incidence of MRI abnormalities of the sellar region differ significantly between the IGHD and MPHD groups.

Pituitary stalk interruption syndrome

Pituitary stalk interruption syndrome (PSIS) is a distinct developmental defect of the pituitary gland identified by magnetic resonance imaging and characterized by a thin, interrupted, attenuated or absent pituitary stalk, hypoplasia or aplasia of the adenohypophysis, and an ectopic posterior pituitary. The precise etiology of PSIS still remains elusive or incompletely confirmed in most cases. Adverse perinatal events, including breech delivery and hypoxia, were initially proposed as the underlying mechanism affecting the hypothalamic-pituitary axis. Nevertheless, recent findings have uncovered a wide variety of PSIS-associated molecular defects in genes involved in pituitary development, holoprosencephaly (HPE), neural development, and other important cellular processes such as cilia function. The application of whole exome sequencing (WES) in relatively large cohorts has identified an expanded pool of potential candidate genes, mostly related to the Wnt, Notch, and sonic hedgehog signaling pathways that regulate pituitary growth and development during embryogenesis. Importantly, WES has revealed coexisting pathogenic variants in a significant number of patients; therefore, pointing to a multigenic origin and inheritance pattern of PSIS. The disorder is characterized by inter- and intrafamilial variability and incomplete or variable penetrance. Overall, PSIS is currently viewed as a mild form of an expanded HPE spectrum. The wide and complex clinical manifestations include evolving pituitary hormone deficiencies (with variable timing of onset and progression) and extrapituitary malformations. Severe and life-threatening symptomatology is observed in a subset of patients with complete pituitary hormone deficiency during the neonatal period. Nevertheless, most patients are referred later in childhood for growth retardation. Prompt and appropriate hormone substitution therapy constitutes the cornerstone of treatment. Further studies are needed to uncover the etiopathogenesis of PSIS.

Short and Long-Term Effects of Growth Hormone in Children and Adolescents With GH Deficiency

The syndrome of impaired GH secretion (GH deficiency) in childhood and adolescence had been identified at the end of the 19^th century. Its non-acquired variant (naGHD) is, at childhood onset, a rare syndrome of multiple etiologies, predominantly characterized by severe and permanent growth failure culminating in short stature. It is still difficult to diagnose GHD and, in particular, to ascertain impaired GH secretion in comparison to levels in normally-growing children. The debate on what constitutes an optimal diagnostic process continues. Treatment of the GH deficit via replacement with cadaveric pituitary human GH (pit-hGH) had first been demonstrated in 1958, and opened an era of therapeutic possibilities, albeit for a limited number of patients. In 1985, the era of recombinant hGH (r-hGH) began: unlimited supply meant that substantial long-term experience could be gained, with greater focus on efficacy, safety and costs. However, even today, the results of current treatment regimes indicate that there is still a substantial fraction of children who do not achieve adult height within the normal range. Renewed evaluation of height outcomes in childhood-onset naGHD is required for a better understanding of the underlying causes, whereby the role of various factors - diagnostics, treatment modalities, mode of treatment evaluation - during the important phases of child growth - infancy, childhood and puberty - are further explored.

Differences between patients with isolated GH deficiency based on findings in brain magnetic resonance imaging

INTRODUCTION

Protocol for prescribing hormone replacement therapy in isolated growth hormone (GH) deficiency includes magnetic resonance imaging of the brain. There is controversy on the frequency of structural pituitary abnormalities and on the importance of abnormal MRI findings on prognosis and response to GH replacement.

METHODS

A descriptive, retrospective study of children of both sexes aged 0-14 years, who had undergone brain MRI, diagnosed with isolated GH deficiency at a tertiary hospital in the past 14 years, aimed at reporting the frequency of abnormal MRI findings in isolated GH deficiency, and to establish whether differences exist in height diagnosis and evolution according to MRI findings. MRI findings were also compared with the findings reported in healthy children in order to establish incidence.

RESULTS

96 patients were studied, of whom 74/96 (77%) reached adult age. Abnormal MRI findings were seen in 11.5% of them (8/11 of pituitary origin). No brain or pituitary tumor was seen in any case. Patients with abnormal images had a mean age at treatment start of 8 years, a target height of -0.8SD, and a final height of 1.04SD, while patients with normal MRI findings had an age at treatment start of 10 years old, a target height of -1.44SD, and a final height of -1.75SD, with statistically significant differences.

CONCLUSIONS

Patients with abnormal MRI findings show a more favorable response to GH replacement therapy.

Development and Validation of a Prediction Rule for Growth Hormone Deficiency Without Need for Pharmacological Stimulation Tests in Children With Risk Factors

INTRODUCTION

Practice guidelines cannot recommend establishing a diagnosis of growth hormone deficiency (GHD) without performing growth hormone stimulation tests (GHST) in children with risk factors, due to the lack of sufficient evidence.

OBJECTIVE

Our goal was to generate an evidence-based prediction rule to diagnose GHD in children with growth failure and clinically identifiable risk factors.

METHODS

We studied a cohort of children with growth failure to build the prediction model, and a second, independent cohort to validate the prediction rule. To this end, we assessed the existence of: pituitary dysgenesis, midline abnormalities, (supra)sellar tumor/surgery, CNS infection, traumatic brain injury, cranial radiotherapy, chemotherapy, genetic GHD, pituitary hormone deficiencies, and neonatal hypoglycemia, cholestasis, or hypogenitalism. Selection of variables for model building was performed using artificial intelligence protocols. Specificity of the prediction rule was the main outcome measure in the validation set.

RESULTS

In the first cohort (n=770), the resulting prediction rule stated that a patient would have GHD if (s)he had: pituitary dysgenesis, or two or more anterior pituitary deficiencies, or one anterior pituitary deficiency plus: neonatal hypoglycemia or hypogenitalism, or diabetes insipidus, or midline abnormalities, or (supra)sellar tumor/surgery, or cranial radiotherapy ≥18 Gy. In the validation cohort (n=161), the specificity of the prediction rule was 99.2% (95% CI: 95.6-100%).

CONCLUSIONS

This clinical rule predicts the existence of GHD with high specificity in children with growth disorders and clinically identifiable risk factors, thus providing compelling evidence to recommend that GHD can be safely diagnosed without recurring to GHST in neonates and children with growth failure and specific comorbidities.

Diagnosis, Genetics, and Therapy of Short Stature in Children: A Growth Hormone Research Society International Perspective

The Growth Hormone Research Society (GRS) convened a Workshop in March 2019 to evaluate the diagnosis and therapy of short stature in children. Forty-six international experts participated at the invitation of GRS including clinicians, basic scientists, and representatives from regulatory agencies and the pharmaceutical industry. Following plenary presentations addressing the current diagnosis and therapy of short stature in children, breakout groups discussed questions produced in advance by the planning committee and reconvened to share the group reports. A writing team assembled one document that was subsequently discussed and revised by participants. Participants from regulatory agencies and pharmaceutical companies were not part of the writing process. Short stature is the most common reason for referral to the pediatric endocrinologist. History, physical examination, and auxology remain the most important methods for understanding the reasons for the short stature. While some long-standing topics of controversy continue to generate debate, including in whom, and how, to perform and interpret growth hormone stimulation tests, new research areas are changing the clinical landscape, such as the genetics of short stature, selection of patients for genetic testing, and interpretation of genetic tests in the clinical setting. What dose of growth hormone to start, how to adjust the dose, and how to identify and manage a suboptimal response are still topics to debate. Additional areas that are expected to transform the growth field include the development of long-acting growth hormone preparations and other new therapeutics and diagnostics that may increase adult height or aid in the diagnosis of growth hormone deficiency.

Congenital Hypopituitarism

Mutations of growth hormone genes and pituitary transcription factors account for a small proportion of cases of severe congenital hypopituitarism. Most cases show characteristic MRI findings of pituitary stalk interruption syndrome. Clinical suspicion should prompt assessment of cortisol, free T4, thyroid-stimulating hormone, and growth hormone levels together with MRI of the hypothalamic and pituitary regions.

Growth Hormone Deficiency in Children: From Suspecting to Diagnosing

Isolated Growth hormone deficiency is an important and treatable cause of short stature. However, it is often difficult to diagnose the condition with certainty due to the lack of a single robust diagnostic test. Short children, other than those with the classical phenotype of immature chubby facies, truncal obesity and micropenis in boys, or those with history of cranial lesions with known association with hypopituitarism, should be evaluated for growth hormone deficiency only after excluding the other more common conditions. These children typically have height markedly below that expected for their midparental height with low height velocity and delayed bone age. Growth hormone levels should be checked by provocative testing, after ensuring that the child is euthyroid, and after priming with sex steroids if indicated. Low levels of Insulin-like growth factor 1 and Insulin-like growth factor binding protein 3 and pituitary abnormalities on neuroimaging provide important corroborative evidence to the diagnosis.

Classical and non-classical causes of GH deficiency in the paediatric age

Growth hormone deficiency (GHD) may result from a failure of hypothalamic GHRH production or release, from congenital disorders of pituitary development, or from central nervous system insults including tumors, surgery, trauma, radiation or infiltration from inflammatory diseases. Idiopathic, isolated GHD is the most common sporadic form of hypopituitarism. GHD may also occur in combination with other pituitary hormone deficiencies, and is often referred to as hypopituitarism, combined pituitary hormone deficiency (CPHD), multiple pituitary hormone deficiency (MPHD) or panhypopituitarism. Children without any identifiable cause of their GHD are commonly labeled as having idiopathic hypopituitarism. MRI imaging is the technique of choice in the diagnosis of children with hypopituitarism. Marked differences in MRI pituitary gland morphology suggest different etiologies of GHD and different prognoses. Pituitary stalk agenesis and ectopic posterior pituitary (EPP) are specific markers of permanent GHD, and patients with these MRI findings show a different clinical and endocrine outcome compared to those with normal pituitary anatomy or hypoplastic pituitary alone. Furthermore, the classic triad of ectopic posterior pituitary gland, pituitary stalk hypoplasia/agenesis, and anterior pituitary gland hypoplasia is generally associated with permanent GHD. T2 DRIVE images aid in the identification of pituitary stalk without the use of contrast medium administration. Future developments in imaging techniques will undoubtedly reveal additional insights. Mutations in a number of genes encoding transcription factors - such as HESX1, SOX2, SOX3, LHX3, LHX4, PROP1, POU1F1, PITX, GLI3, GLI2, OTX2, ARNT2, IGSF1, FGF8, FGFR1, PROKR2, PROK2, CHD7, WDR11, NFKB2, PAX6, TCF7L1, IFT72, GPR161 and CDON - have been associated with pituitary dysfunction and abnormal pituitary gland development; the correlation of genetic mutations to endocrine and MRI phenotypes has improved our knowledge of pituitary development and management of patients with hypopituitarism, both in terms of possible genetic counseling, and of early diagnosis of evolving anterior pituitary hormone deficiencies.

Diagnosis and management of growth disorders in Gulf Cooperation Council (GCC) countries: Current procedures and key recommendations for best practice

Diagnosis and management of growth disorders comprises an important area of pediatric practice. Current procedures in the different stages of the identification, referral, investigation, and treatment of growth disorders in the Gulf Cooperation Council (GCC) countries have been summarized. Evidence-based procedures, relating specifically to height screening for identification of short stature, auxological criteria for patient referral from primary to secondary pediatric care, and general and endocrine investigations and diagnosis have been discussed and outlined. The management issues related to key disorders that are licensed for growth hormone (hGH) therapy, namely GH deficiency, Turner syndrome, short stature related to birth size small for gestational age (SGA), and idiopathic short stature are discussed with recommendations described for best practice. Finally, two key components of short stature management, namely transitional care for the transfer of patients from pediatric to adult endocrinology services and adherence to recommended therapy with hGH, have been addressed with current practice outlines and recommendations presented.

Pituitary stalk interruption syndrome: cause, clinical manifestations, diagnosis, and management

PURPOSE OF REVIEW

Pituitary stalk interruption syndrome (PSIS) is characterized by a thin or absent pituitary stalk, hypoplasia of the adenohypophysis, and ectopic neurohypophysis. PSIS manifestations include a wide spectrum of clinical phenotypes and pituitary hormone deficiencies of variable degree and timing of onset. In this review, recent advances with respect to the cause of PSIS, clinical characteristics leading to earlier diagnosis, and management are outlined.

RECENT FINDINGS

Diagnosis of PSIS is often delayed probably because clinical findings such as neonatal hypoglycemia, cholestasis, and/or micropenis as well as decreasing growth velocity are not appropriately and timely validated. Recently, molecular defects in various genes have been associated with PSIS albeit in a small number of cases. These findings suggest that PSIS belongs to the spectrum of holoprosencephaly-related defects. Phenotype-genotype discordance and the existence of asymptomatic carriers of a given molecular aberration indicate that penetrance may be modified favorably or unfavorably by the presence of other genetic and/or environmental factors.

SUMMARY

PSIS constitutes an antenatal anatomical defect. Neonatal hypoglycemia, cholestasis, and/or micropenis with or without growth deficit should raise the possibility of combined pituitary hormone deficiency, a life-threatening condition in cases of coexisting cortisol deficiency. It is important to search for molecular defects in all PSIS cases, as precise identification of the cause is a prerequisite for genetic counseling.