Hypothalamic-pituitary dysfunction in growth hormone-deficient patients with pituitary abnormalities

Advances in differential diagnosis and management of growth hormone deficiency in children

Growth hormone (GH) deficiency (GHD) in children is defined as impaired production of GH by the pituitary gland that results in growth failure. This disease might be congenital or acquired, and occurs in isolation or in the setting of multiple pituitary hormone deficiency. Isolated GHD has an estimated prevalence of 1 patient per 4000-10,000 live births and can be due to multiple causes, some of which are yet to be determined. Establishing the correct diagnosis remains key in children with short stature, as initiating treatment with recombinant human GH can help them attain their genetically determined adult height. During the past two decades, our understanding of the benefits of continuing GH therapy throughout the transition period from childhood to adulthood has increased. Improvements in transitional care will help alleviate the consequent physical and psychological problems that can arise from adult GHD, although the consequences of a lack of hormone replacement are less severe in adults than in children. In this Review, we discuss the differential diagnosis in children with GHD, including details of clinical presentation, neuroimaging and genetic testing. Furthermore, we highlight advances and issues in the management of GHD, including details of transitional care.

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.

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.

Chronic prenatal heat stress alters growth, carcass composition, and physiological response of growing pigs subjected to postnatal heat stress

Postnatal heat stress (HS) effects on pig physiology and performance are widely studied but prenatal HS studies, albeit increasing, are still limited. The objective of this study was to evaluate the chronic prenatal HS effects in growing pigs raised in postnatal thermoneutral (TN) or in HS environment. For prenatal environment (PE), mixed-parity pregnant sows were exposed to either TN (PTN; cyclic 18 to 24 °C; n = 12) or HS (PHS; cyclic 28 to 34 °C; n = 12) conditions from day 9 to 109 of gestation. Two female offspring per sow were selected at 10 wk of age and allotted to one of two postnatal growing environments (GE): GTN (cyclic 18 to 24 °C; n = 24) and GHS (cyclic 28 to 34 °C; n = 24). From 75 to 140 d of age, GTN pigs remained in GTN conditions, while GHS pigs were in GTN conditions from 75 to 81 d of age and in GHS conditions from 82 to 140 d of age. Regardless of PE, postnatal HS increased rectal and skin temperatures (+0.30 and +1.61 °C on average, respectively; P < 0.01) and decreased ADFI (-332 g/d; P < 0.01), resulting in lower ADG and final BW (-127 g/d and -7.9 kg, respectively; P < 0.01). The GHS pigs exhibited thicker backfat (P < 0.01), lower carcass loin percentage (P < 0.01), increased plasma creatinine levels (P < 0.01), and decreased plasma glucose, nonesterified fatty acids, T3, and T4 levels (P < 0.05). Prenatal HS increased feed intake in an age-dependent manner (+10 g·kg BW-0.60·d-1 for PHS pigs in the last 2 wk of the trial; P = 0.02) but did not influence BW gain (P > 0.10). Prenatal HS decreased the plasma levels of superoxide dismutase on day 3 of GHS (trend at P = 0.08) and of T4 on day 49 (P < 0.01) but did not affect T3 on day 3 nor 49 (P > 0.10). Prenatal HS increased rectal and skin temperatures and decreased temperature gradient between rectal and skin temperatures in GTN pigs (+0.10, +0.33 and -0.22 °C, respectively; P < 0.05) but not in GHS pigs (P > 0.10). There were also PE × GE interactions found with lower BW (P = 0.06) and higher backfat (P < 0.01) and perirenal adiposity (P < 0.05) for GHS-PHS pigs than the other groups. Overall, increased body temperature and altered thyroid functions and physiological stress responses suggest decreased heat tolerance and dissipation ability of pigs submitted to a whole-gestation chronic prenatal HS. Postnatal HS decreased growth performance, increased carcass adiposity, and affected metabolic traits and thyroid functions especially in pigs previously submitted to prenatal HS.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY GUIDELINES FOR MANAGEMENT OF GROWTH HORMONE DEFICIENCY IN ADULTS AND PATIENTS TRANSITIONING FROM PEDIATRIC TO ADULT CARE

Objective: The development of these guidelines is sponsored by the American Association of Clinical Endocrinologists (AACE) Board of Directors and American College of Endocrinology (ACE) Board of Trustees and adheres with published AACE protocols for the standardized production of clinical practice guidelines (CPG). Methods: Recommendations are based on diligent reviews of clinical evidence with transparent incorporation of subjective factors, according to established AACE/ACE guidelines for guidelines protocols. Results: The Executive Summary of this 2019 updated guideline contains 58 numbered recommendations: 12 are Grade A (21%), 19 are Grade B (33%), 21 are Grade C (36%), and 6 are Grade D (10%). These detailed, evidence-based recommendations allow for nuance-based clinical decision-making that addresses multiple aspects of real-world care of patients. The evidence base presented in the subsequent Appendix provides relevant supporting information for the Executive Summary recommendations. This update contains 357 citations of which 51 (14%) are evidence level (EL) 1 (strong), 168 (47%) are EL 2 (intermediate), 61 (17%) are EL 3 (weak), and 77 (22%) are EL 4 (no clinical evidence). Conclusion: This CPG is a practical tool that practicing endocrinologists and regulatory bodies can refer to regarding the identification, diagnosis, and treatment of adults and patients transitioning from pediatric to adult-care services with growth hormone deficiency (GHD). It provides guidelines on assessment, screening, diagnostic testing, and treatment recommendations for a range of individuals with various causes of adult GHD. The recommendations emphasize the importance of considering testing patients with a reasonable level of clinical suspicion of GHD using appropriate growth hormone (GH) cut-points for various GH-stimulation tests to accurately diagnose adult GHD, and to exercise caution interpreting serum GH and insulin-like growth factor-1 (IGF-1) levels, as various GH and IGF-1 assays are used to support treatment decisions. The intention to treat often requires sound clinical judgment and careful assessment of the benefits and risks specific to each individual patient. Unapproved uses of GH, long-term safety, and the current status of long-acting GH preparations are also discussed in this document. LAY ABSTRACT This updated guideline provides evidence-based recommendations regarding the identification, screening, assessment, diagnosis, and treatment for a range of individuals with various causes of adult growth-hormone deficiency (GHD) and patients with childhood-onset GHD transitioning to adult care. The update summarizes the most current knowledge about the accuracy of available GH-stimulation tests, safety of recombinant human GH (rhGH) replacement, unapproved uses of rhGH related to sports and aging, and new developments such as long-acting GH preparations that use a variety of technologies to prolong GH action. Recommendations offer a framework for physicians to manage patients with GHD effectively during transition to adult care and adulthood. Establishing a correct diagnosis is essential before consideration of replacement therapy with rhGH. Since the diagnosis of GHD in adults can be challenging, GH-stimulation tests are recommended based on individual patient circumstances and use of appropriate GH cut-points. Available GH-stimulation tests are discussed regarding variability, accuracy, reproducibility, safety, and contraindications, among other factors. The regimen for starting and maintaining rhGH treatment now uses individualized dose adjustments, which has improved effectiveness and reduced reported side effects, dependent on age, gender, body mass index, and various other individual characteristics. With careful dosing of rhGH replacement, many features of adult GHD are reversible and side effects of therapy can be minimized. Scientific studies have consistently shown rhGH therapy to be beneficial for adults with GHD, including improvements in body composition and quality of life, and have demonstrated the safety of short- and long-term rhGH replacement. Abbreviations: AACE = American Association of Clinical Endocrinologists; ACE = American College of Endocrinology; AHSG = alpha-2-HS-glycoprotein; AO-GHD = adult-onset growth hormone deficiency; ARG = arginine; BEL = best evidence level; BMD = bone mineral density; BMI = body mass index; CI = confidence interval; CO-GHD = childhood-onset growth hormone deficiency; CPG = clinical practice guideline; CRP = C-reactive protein; DM = diabetes mellitus; DXA = dual-energy X-ray absorptiometry; EL = evidence level; FDA = Food and Drug Administration; FD-GST = fixed-dose glucagon stimulation test; GeNeSIS = Genetics and Neuroendocrinology of Short Stature International Study; GH = growth hormone; GHD = growth hormone deficiency; GHRH = growth hormone-releasing hormone; GST = glucagon stimulation test; HDL = high-density lipoprotein; HypoCCS = Hypopituitary Control and Complications Study; IGF-1 = insulin-like growth factor-1; IGFBP = insulin-like growth factor-binding protein; IGHD = isolated growth hormone deficiency; ITT = insulin tolerance test; KIMS = Kabi International Metabolic Surveillance; LAGH = long-acting growth hormone; LDL = low-density lipoprotein; LIF = leukemia inhibitory factor; MPHD = multiple pituitary hormone deficiencies; MRI = magnetic resonance imaging; P-III-NP = procollagen type-III amino-terminal pro-peptide; PHD = pituitary hormone deficiencies; QoL = quality of life; rhGH = recombinant human growth hormone; ROC = receiver operating characteristic; RR = relative risk; SAH = subarachnoid hemorrhage; SDS = standard deviation score; SIR = standardized incidence ratio; SN = secondary neoplasms; T3 = triiodothyronine; TBI = traumatic brain injury; VDBP = vitamin D-binding protein; WADA = World Anti-Doping Agency; WB-GST = weight-based glucagon stimulation test.

Role of MRI T2-DRIVE in the assessment of pituitary stalk abnormalities without gadolinium in pituitary diseases

OBJECTIVE

To investigate the role of T2-DRIVE MRI sequence in the accurate measurement of pituitary stalk (PS) size and the identification of PS abnormalities in patients with hypothalamic-pituitary disorders without the use of gadolinium.

DESIGN

This was a retrospective study conducted on 242 patients who underwent MRI due to pituitary dysfunction between 2006 and 2015. Among 135 eligible patients, 102 showed eutopic posterior pituitary (PP) gland and 33 showed 'ectopic' PP (EPP).

METHODS

Two readers independently measured the size of PS in patients with eutopic PP at the proximal, midpoint and distal levels on pre- and post-contrast T1-weighted as well as T2-DRIVE images; PS visibility was assessed on pre-contrast T1 and T2-DRIVE sequences in those with EPP. The length, height, width and volume of the anterior pituitary (AP), PP height and length and PP area were analyzed.

RESULTS

Significant agreement between the two readers was obtained for T2-DRIVE PS measurements in patients with 'eutopic' PP; a significant difference was demonstrated between the intraclass correlation coefficient calculated on the T2-DRIVE and the T1-pre- and post-contrast sequences. The percentage of PS identified by T2-DRIVE in EPP patients was 72.7% compared to 30.3% of T1 pre-contrast sequences. A significant association was found between the visibility of PS on T2-DRIVE and the height of AP.

CONCLUSION

T2-DRIVE sequence is extremely precise and reliable for the evaluation of PS size and the recognition of PS abnormalities; the use of gadolinium-based contrast media does not add significant information and may thus be avoided.

Correlation between adrenal function, growth hormone secretion, and insulin sensitivity in children with idiopathic growth hormone deficiency

PURPOSE

Patients with growth hormone deficiency (GHD) demonstrate an increased cortisol/cortisone ratio which could potentially explain the metabolic features of GHD, while GH treatment (GHT) could increase the cortisol metabolism.

METHODS

In 35 children (27 M, mean age 10.1 years) with idiopathic GHD at baseline and after 12 months of GHT and in 25 controls, in addition to metabolic parameters, we assessed adrenal function by morning serum cortisol, its peak, and its area under the curve (AUC_COR) during insulin tolerance test (ITT).

RESULTS

A cortisol peak <18 µg/dl was shown in 22 and 31% of GHD children at baseline and after GHT, respectively. At baseline, GHD children had lower fasting glucose (p < 0.001) and ISI-Matsuda (p = 0.042), with concomitant higher Homa-IR (p = 0.006) and morning cortisol (p = 0.012) than controls. Morning cortisol was negatively correlated with GH (p < 0.001), fasting glucose (p < 0.001) and ISI-Matsuda (p < 0.001) and positively with Homa-IR (p = 0.010). Both cortisol peak and AUC_COR were negatively correlated with GH (all p < 0.001) and ISI-Matsuda (p = 0.016 and p = 0.001, respectively). After 12 months of GHT, a significant increase in fasting glucose (p < 0.001), and Homa-IR (p = 0.011) was documented, with a concomitant decrease in morning cortisol (p = 0.002), AUC_COR (p = 0.038), total (p = 0.003) and LDL-cholesterol (p = 0.016). No significant correlations were found among cortisol levels and all parameters were investigated.

CONCLUSIONS

Cortisol levels correlate with GH secretion and with many metabolic parameters in GHD children, while the metabolic effects during GHT are mainly due to GHT per se and less to cortisol reduction.

Progression from isolated growth hormone deficiency to combined pituitary hormone deficiency

Growth hormone deficiency (GHD) can present at any time of life from the neonatal period to adulthood, as a result of congenital or acquired insults. It can present as an isolated problem (IGHD) or in combination with other pituitary hormone deficiencies (CPHD). Pituitary deficits can evolve at any time from GHD diagnosis. The number, severity and timing of occurrence of additional endocrinopathies are highly variable. The risk of progression from IGHD to CPHD in children varies depending on the etiology (idiopathic vs organic). The highest risk is displayed by children with abnormalities in the Hypothalamo-Pituitary (H-P) region. Heterogeneous data have been reported on the type and timing of onset of additional pituitary hormone deficits, with TSH deficiency being most frequent and Diabetes Insipidus the least frequent additional deficit in the majority, but not all, of the studies. ACTH deficiency may gradually evolve at any time during follow-up in children or adults with childhood onset IGHD, particularly (but not only) in presence of H-P abnormalities and/or TSH deficiency. Hence there is a need in these patients for lifelong monitoring for ACTH deficiency. GH treatment unmasks central hypothyroidism mainly in patients with organic GHD, but all patients starting GH should have their thyroid function monitored closely. Main risk factors for development of CPHD include organic etiology, H-P abnormalities (in particular pituitary stalk abnormalities, empty sella and ectopic posterior pituitary), midline brain (corpus callosum) and optic nerves abnormalities, genetic defects and longer duration of follow-up. The current available evidence supports longstanding recommendations for the need, in all patients diagnosed with IGHD, of a careful and indefinite follow-up for additional pituitary hormone deficiencies.

Extra-pituitary Cerebral Anomalies in Pediatric Patients of Ectopic Neurohypophysis: An Uncommon Association

Context:

Ectopic neurohypophysis (EN) refers to an interrupted, nonvisualized, and thinned out pituitary stalk with ectopic location of the posterior pituitary gland. Concurrent extra-pituitary cerebral and extra-cranial anomalies have been rarely reported in patients of EN.

Aim:

The aim of this study was to evaluate the magnetic resonance imaging (MRI) findings of extra-pituitary cerebral anomalies in pediatric patients of EN.

Settings and Design:

A hospital-based cross-sectional study was conducted in a tertiary care center.

Subjects and Methods:

The study group comprised eight pediatric patients of EN associated with extra-pituitary cerebral or vascular anomalies. Clinical and biochemical assessment was done in all patients.

Results:

Out of the total eight patients with EN, MRI showed interrupted pituitary stalk in five patients (62.5%) and nonvisible pituitary stalk in three patients (37.5%). Ectopic posterior pituitary bright spot was demonstrated in median eminence in six patients (75%), faintly visualized in one patient (12.5%) and nonvisualized in another one patient. Statistical significant association was noted between pituitary gland height and patient's body height with the pituitary gland volume (P < 0.001). Varied extra-pituitary cerebral anomalies encountered in our patients ranged from isolated anomalies such as optic nerve hypoplasia in three patients (37.5%), corpus callosum dysplasia in four patients (50%), agyria-pachygyria complex in two patients (25%), and intracranial vascular anomalies in two patients to syndromic association of tuberous sclerosis in one patient.

Conclusion:

Identifying and reporting of associated extra-pituitary cerebral anomalies in patients with EN are crucial in assessing the overall neurological outcome of such patients.

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.

Neuroradiologia funzionale della ghiandola ipofisaria

Lo studio sequenziale dell'afflusso del mezzo di contrasta a carico del parenchima ipofisario è stato di recente valutato da diversi autori, utilizzando apparecchiature operanti a 1,5 T. Tutta-via, con l'eccezione di 3 casi di macroadenoma, non sono state mai valutate le possibili alterazioni di flus-so ghiandolare nelle diverse affezioni interessanti l'ipofisi. Sono stati esaminati 27 volontari non affetti da patologia ipofisaria e 47 pazienti, in età pediatrica o adulti, affetti da alterazioni ipofisarie su base congenita o acquisita. I pazienti sono stati valutati mediante apparecchiatura operante a medio campo, compa-rando i risultati, ottenuti in tempi diversi, di una valutazione ipofisaria standard versus un esame di tipo sequenziale.

Il nostro studio ha dimostrato un modello di accentuazione delle differenti componenti ghiandolari perfettamente corrispondente all'organizzazione microvascolare della ghiandola stessa, con un incremen-to dell'intensità di segnale apprezzabile prima a livello neuroipofisario, poi a carico del peduncolo e della parte prossimale dell'adenoipofisi, ed infine a carico della pars distalis adenoipofisaria. I microadenomi hanno dimostrato un modello di accentuazione di tipo <arterioso>, in rapporto alla neoangiogenesi esi-stente. I macroadenomi hanno dimostrato un modello differente, nelle aree esaminate, in dipendenza del-l'estensione. Nessuna alterazione è stata riscontrata nei pazienti affetti da sella vuota parziale. I pazienti affetti da deficit di ormone della crescita hanno dimostrato una riduzione del potenziamento del peduncolo ipofisario, in possibile relazione a danno del sistema vascolare portale.

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

BACKGROUND/AIMS

The diagnosis of growth hormone (GH) deficiency (GHD) in infancy and early childhood is not straightforward. GH stimulation tests are unsafe and unreliable in infants, and normative data are lacking. This study aims to investigate whether brain magnetic resonance imaging (MRI) may replace GH stimulation tests in the diagnosis of GHD in children younger than 4 years.

METHODS

We examined a retrospective cohort, with longitudinal follow-up, of 68 children consecutively diagnosed with GHD before the age of 4 years. The prevalence of hypothalamic-pituitary (HP) alterations at MRI and the associations with age and either isolated GHD (IGHD) or multiple pituitary hormone deficiency (MPHD) were assessed.

RESULTS

The prevalences of IGHD and MPHD were 54.4 and 45.6%, respectively. In the first group, brain MRI showed abnormalities in 83.8%: isolated pituitary hypoplasia in 48.7% and complex defects in 35.1%. In patients with MPHD, MRI showed complex alterations in 100%. All children younger than 24 months showed HP MRI abnormalities, regardless of the diagnosis. Complex defects were found in 94% of patients younger than 12 months and in 75% of patients between 13 and 24 months.

CONCLUSION

Our data suggest that brain MRI may represent the first-line investigation for diagnosing GHD in infancy and early childhood.

MRI findings of coexistence of ectopic neurohypophysis, corpus callosum dysgenesis, and periventricular neuronal heterotopia

Ectopic neurohypophysis is a pituitary gland abnormality, which can accompany growth hormone deficiency associated with dwarfism. Here we present magnetic resonance imaging (MRI) findings of a rare case of ectopic neurohypophysis, corpus callosum dysgenesis, and periventricular neuronal heterotopia coexisting, with a review of the literature.

Anti-mullerian hormone deficiency in girls with congenital multiple pituitary hormone deficiency

CONTEXT

Anti-Mullerian hormone (AMH) is believed to validly reflect the ovarian reserve. We wanted to test whether congenital absence of gonadotropin stimulation of the ovaries affects AMH production.

OBJECTIVE

The objective of the study was to test the validity of AMH as a marker for the ovarian reserve in females with congenital multiple pituitary hormone deficiency (MPHD; deficiency of three or more axes).

DESIGN

This was a retrospective laboratory study.

SETTING

The study was conducted in the Department of Pediatric Endocrinology in a tertiary center.

PATIENTS

The AMH serum levels were assessed in females with congenital (n = 16; median age 12.5 y, range 0.7-31 y) or acquired (n = 20; 18.5 y, range 2-33 y) MPHD and in controls with short stature (n = 100; 9.7 y, range 2-17 y).

MAIN OUTCOME MEASURE

AMH was measured by AMH Gen II ELISA from Beckmann Coulter.

RESULTS

In the controls, AMH ranged between 1.8 (P3) and 67.8 pmol/L (P97). Three patients with a severe form of congenital MPHD were AMH deficient, whereas the other 33 patients with MPHD had normal AMH levels. There was significantly more AMH deficiency in congenital than in acquired MPHD (P < .05).

CONCLUSIONS

Most girls with MPHD have normal serum AMH levels. However, some females with severe congenital MPHD are AMH deficient. This deficiency might be the result of the total absence of gonadotropins. In these females, AMH is unlikely to be an accurate prognostic parameter of the efficacy of fertility treatment.

Congenital Growth Hormone Deficiency - A Review with a Focus on Neuroimaging

Growth hormone deficiency is an important cause of short stature in childhood. It is characterised by low growth velocity in childhood and is diagnosed by stimulation testing. Individuals with growth hormone deficiency may have other pituitary hormone deficits in addition to growth hormone deficiency. When multiple pituitary hormone deficiencies are present, abnormal pituitary anatomy, as visualised on magnetic resonance imaging (MRI), is a frequent finding. The classic triad (ectopic posterior pituitary, hypoplastic or aplastic anterior pituitary and absent/thin pituitary stalk) or variants of the classic triad are commonly seen in these patients. Volumetric sequencing allows all three planes of visualisation to be reconstructed in post-processing, allowing the radiologist to more fully evaluate pituitary anatomy. The normal dimensions of the pituitary gland vary by age and precise definitions of what constitutes a hypoplastic gland are not clearly defined in the medical literature. Having an experienced neuroradiologist interpret the MRI in patients with pituitary dysfunction is very important.

Pituitary stalk transection syndrome: Comparison of clinico-radiological features in adults and children with review of literature

Hypo-pituitarism results from impaired production of one or more of anterior pituitary trophic hormones. A rare cause of hypo-pituitarism is pituitary stalk transection syndrome. The MRI features of this condition in children and its association with hormonal deficiencies have been reported earlier. Reports on adults with this disorder are scarce, with only one small case series published in the recent literature. We studied the hormonal deficiency pattern and MRI findings of 12 patients with pituitary stalk transection syndrome who presented to our department between 2004 and 2011. Six patients were children and six were adults (≥18 years). This article compares the adult clinico-radiological phenotype of pituitary transection syndrome with the pediatric group of patients with same condition.

A retrospective review of pituitary MRI findings in children on growth hormone therapy

BACKGROUND

Patients with congenital hypopituitarism might have the classic triad of pituitary stalk interruption syndrome, which consists of: (1) an interrupted or thin pituitarys talk, (2) an absent or ectopic posterior pituitary (EPP), and (3) anterior pituitary hypoplasia or aplasia.

OBJECTIVE

To examine the relationship between pituitary anatomy and the degree of hormonal dysfunction.

MATERIALS AND METHODS

This study involved a retrospective review of MRI findings in all children diagnosed with congenital growth hormone deficiency from 1988 to 2010 at a tertiary-level pediatric hospital.

RESULTS

Of the 52 MRIs reviewed in 52 children, 26 children had normal pituitary anatomy and 26 had one or more elements of the classic triad. Fourteen of fifteen children with multiple pituitary hormone deficiencies had structural anomalies on MRI. Twelve of 37 children with isolated growth hormone deficiency had an abnormal MRI.

CONCLUSION

Children with multiple pituitary hormone deficiencies were more likely to have the classic triad than children with isolated growth hormone deficiency. A normal MRI was the most common finding in children with isolated growth hormone deficiency.

The use of neuroimaging for assessing disorders of pituitary development

Magnetic resonance imaging (MRI) is the radiological examination method of choice for evaluating hypothalamo-pituitary-related endocrine disease and is considered essential in the assessment of patients with suspected hypothalamo-pituitary pathology. Physicians involved in the care of such patients have, in MRI, a valuable tool that can aid them in determining the pathogenesis of their patients' underlying pituitary conditions. Indeed, the use of MRI has led to an enormous increase in our knowledge of pituitary morphology, improving, in particular, the differential diagnosis of hypopituitarism. Specifically, MRI allows detailed and precise anatomical study of the pituitary gland by differentiating between the anterior and posterior pituitary lobes. MRI recognition of pituitary hyperintensity in the posterior part of the sella, now considered a marker of neurohypophyseal functional integrity, has been the most striking finding in the diagnosis and understanding of certain forms of 'idiopathic' and permanent growth hormone deficiency (GHD). Published data show a number of correlations between pituitary abnormalities as observed on MRI and a patient's endocrine profile. Indeed, several trends have emerged and have been confirmed: (i) a normal MRI or anterior pituitary hypoplasia generally indicates isolated growth hormone deficiency that is mostly transient and resolves upon adult height achievement; (ii) patients with multiple pituitary hormone deficiencies (MPHD) seldom show a normal pituitary gland; and (iii) the classic triad of ectopic posterior pituitary, pituitary stalk hypoplasia/agenesis and anterior pituitary hypoplasia is more frequently reported in MPHD patients and is generally associated with permanent GHD. Pituitary abnormalities have also been reported in patients with hypopituitarism carrying mutations in several genes encoding transcription factors. Establishing endocrine and MRI phenotypes is extremely useful for the selection and management of patients with hypopituitarism, both in terms of possible genetic counselling and in the early diagnosis of evolving anterior pituitary hormone deficiencies. Going forward, neuroimaging techniques are expected to progressively expand and improve our knowledge and understanding of pituitary diseases.

Usefulness of magnetic resonance findings of the hypothalamic-pituitary region in the management of short children with growth hormone deficiency: evidence from a longitudinal study

PURPOSE

The purpose of this study is to assess the relationship between magnetic resonance images (MRI) of the hypothalamic-pituitary (H-P) region and response to recombinant human growth hormone (rhGH) treatment in short children with growth hormone deficiency, basing on changes of auxologic parameters, as well as to answer the question if MRI may serve for selecting and monitoring the rhGH responders.

PATIENTS AND METHODS

The study group comprised 85 children treated with rhGH, aged 7.3-18.7 years, followed for the mean period of 3.2 years (range, 2.1-9.5 years). Auxologic parameters (height deficit hSDS, deviation from the mid-parental height hSDS-mpSDS, bone delay index bone age/chronological age ratio (BA/CA)) were assessed before, during and at the end of rhGH treatment; growth velocity was calculated before and during rhGH therapy. Parameters were correlated with the MRI of the H-P region.

RESULTS

Structural anomalies of the H-P region were found in 22 (25.9%) children: empty sella syndrome (ESS) in 12 (14.1%) patients, ectopic posterior pituitary (EPP) in ten (11.8%). Patients' height deficit and their deviation from parental height before rhGH therapy was significantly greater in the EPP group (median hSDS = -3.8; hSDS-mpSDS = -2.5), bone age delay was the greatest in the ESS group (median BA/CA = 0.69), after therapy - in the EPP group (median BA/CA = 0.82). Growth velocity improved in the first year of the rhGH therapy in all groups; however, the most significant acceleration was observed in the EPP group (median delta hSDS = 0.9), then stabilised and was comparable in all groups.

CONCLUSIONS

MRI may be helpful in predicting response to the rhGH treatment, providing midline abnormalities are taken into account.

Oral manifestation associated with multiple pituitary hormone deficiency and ectopic neurohypophysis

Multiple pituitary hormone deficiency (MPHD) is the diminished secretion of all the hormones produced in the anterior lobe of the pituitary gland. The oral manifestation of this condition includes delayed eruption and prolonged retention of primary teeth, delayed formation and eruption of permanent teeth, delay in development and growth of the jaws, tendency towards development of deep bite and enamel disturbances. This paper reports the case of an adolescent patient with MPHD. Clinical examination revealed partial ankylosis and prolonged retention ofprimary second molars, primary maxillary canines and deep bite. Dental treatment included extraction of all molars with prolonged retention preceded by the necessary medical care with clinical and radiographic follow-up afterwards. The patient was also referred to an orthodontist for orthodontic treatment. Patients' medical condition should always be investigated by clinicians when faced with cases of delayed tooth eruption and bone development.

The accuracy of the glucagon test compared to the insulin tolerance test in the diagnosis of adrenal insufficiency in young children with growth hormone deficiency

CONTEXT

The accuracy of the glucagon test in the diagnosis of central adrenal insufficiency in young children has not yet been definitively established.

OBJECTIVE

The aim of this study was to investigate the diagnostic accuracy of the glucagon test as an alternative to the insulin tolerance test (ITT) in children with GH deficiency under 6 yr of age.

DESIGN AND SETTING

This was a prospective study conducted in two Pediatric Endocrinology Centers.

PATIENTS AND METHODS

Forty-eight children (median age, 4.2 yr) with GH deficiency confirmed by a peak GH to ITT and arginine less than 10 microg/liter were enrolled: 24 with normal hypothalamic-pituitary anatomy, seven with isolated anterior pituitary hypoplasia, and 17 with structural hypothalamic-pituitary abnormalities at magnetic resonance imaging. Twelve subjects had central adrenal insufficiency defined by a peak cortisol response of less than 20 microg/dl to ITT. All children underwent a glucagon stimulation test with blood sampling for cortisol and glucose (time 0 to 180 min) after the im administration of 30 microg/kg of glucagon.

RESULTS

The mean peak cortisol after glucagon was not significantly different from that obtained after ITT in the whole cohort (25.9 vs. 26.0 microg/dl; P = 0.908), and it was significantly reduced in patients with structural hypothalamic-pituitary abnormalities (P < 0.001). Receiver operating characteristic curve analysis showed that the best diagnostic accuracy was obtained with a peak cortisol cutoff to glucagon of 14.6 microg/dl (sensitivity, 66.67%; specificity, 100%; area under the curve = 0.91; 95% confidence interval, 0.82-0.99). Using this cutoff, 91.67% of the patients were correctly classified.

CONCLUSIONS

This study shows that glucagon is an accurate and safe diagnostic test for adrenal function in young children who are at risk for adrenal insufficiency.

Gonadotrophic status in adolescents with pituitary stalk interruption syndrome

OBJECTIVE

Pituitary stalk interruption syndrome (PSIS) is a frequent cause of GH deficiency (GHD) and is commonly associated with other PH deficiencies (PHDs). Although previous reports have correlated multiple PHDs with severe anatomical lesions, the status of the gonadotrophic axis has not yet been thoroughly analysed.

METHODS

We retrospectively reviewed the medical records of 27 patients (15 males, 12 females) with GHD and PSIS defined by MRI findings. The status of the gonadotrophic axis was evaluated in children who were at least 14.5 years (boys) or 13 years (girls).

RESULTS

Out of 27 patients, five displayed spontaneous full pubertal development with normal hormonal values at the final evaluation, whereas 22 of 27 patients (81%) had complete (n = 18) or partial pubertal deficiency. Three girls had primary amenorrhoea with normal gonadotrophin values, raising the possibility of subtle disturbances of gonadotrophin pulsatility. Of the 21 patients with TSH or ACTH deficiency, 17 (81%) had complete gonadotrophin deficiency. Two of our six patients with apparently isolated GHD during childhood had gonadotrophin deficiency. Cryptorchidism was present at birth in six boys (40%). Of these six boys, one had normal pubertal development. Ten of 11 boys with micropenis at birth had gonadotrophin deficiency.

CONCLUSIONS

Gonadotrophin deficiency is a common finding in adolescents with PSIS and is frequently associated with other PHDs. However its severity is variable, ranging from complete gonadotrophin deficiency to normogonadotrophic amenorrhoea. The occurrence of gonadotrophin deficiency in 33% of children with apparently isolated GHD and PSIS has important implications for the counselling and follow-up of these patients.

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

CONTEXT

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

OBJECTIVES

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

DESIGN AND SETTING

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Clinical, hormonal and imaging findings in 27 children with central diabetes insipidus

Clinical, auxological, biological and neuroradiological characteristics of 27 children with central diabetes insipidus (CDI) were retrospectively analysed. Median age at diagnosis was 8.6 years (range: 0.3-16.1 years). Final aetiologies were postsurgical infundibulo-hypophyseal impairment (n=7), cerebral tumour (n=8), Langerhans cell histiocytosis (n=3), septo-optic dysplasia (n=1), ectrodactyly ectodermal dysplasia clefting syndrome (n=1), and idiopathic (n=7). In the non-postsurgical CDI patients, major cumulative and often subtle presenting manifestations were: polyuria (n=20), polydipsia (n=19), fatigue (n=11), nycturia (n=10), growth retardation (n=9), and headache (n=9). An associated antehypophyseal insufficiency, mainly somatotropic, was documented in 11 children. All patients except one who initially had a cerebral tomography, underwent magnetic resonance imaging revealing the lack of the physiological posterior pituitary hyperintense signal. One third of the idiopathic patients initially had a thickened pituitary stalk. All patients with idiopathic CDI were intensively followed up with 3-monthly physical examination, antehypophyseal evaluation, search for tumour markers, and cerebral MRI every 6 months. In one of them the pituitary stalk had normalized after 4.3 years. In one patient Langerhans cell histiocytosis was diagnosed after 7 months of follow-up, and in another patient a malignant teratoma was found after 2.4 years of follow-up.

CONCLUSION

CDI may be the early sign of an evolving cerebral process. The association of polyuria-polydipsia should incite a complete endocrine evaluation and a meticulous MRI evaluation of the hypothalamo-hypophyseal region. A rigorous clinical and neuroradiologic follow-up is mandatory to rule out an evolving cerebral process and to detect associated antehypophyseal insufficiencies.

Hypothalamic-pituitary magnetic resonance imaging in growth hormone deficiency

The accurate analysis of the hypothalamic-pituitary area is essential in the diagnosis of endocrine-related diseases. High-quality magnetic resonance imaging represents the examination modality of choice in the evaluation of hypothalamic-pituitary morphology. Indeed, the advent of molecular biology and neuroimaging techniques has led to significant progress in the understanding of the pathogenesis of disorders affecting the pituitary gland, specifically by demonstrating a clear phenotype-genotype relationship. Animal studies, along with the correlation of a particular genetic profile to certain endocrine and magnetic resonance imaging phenotypes in humans, have yielded great insights into pituitary development. Today, there is convincing evidence to support the hypothesis that marked magnetic resonance imaging differences in pituitary morphology indicate a variety of disorders that affect anterior pituitary gland organogenesis and function with a variety of diverse prognoses.

Long-term follow-up of a girl with primary aldosteronism: effect of potassium supplement

We followed up a girl with primary aldosteronism for 8 y, which was diagnosed at 6 y of age when she was referred to us for evaluation of heart murmur and growth failure. The diagnosis of bilateral adrenal hyperplasia was made by selective adrenal venous sampling. Following potassium supplement, her retarded growth was corrected dramatically, and she attained a normal adult height. Puberty developed normally and menarche occurred at 12 y of age. Blood pressure was also controlled adequately. Myocardial hypertrophy associated with aortic damage was noted at 13 y of age. Chronic renal failure developed with proteinuria and enlarged renal cysts.

CONCLUSION

Serum electrolytes should be included in the evaluation of children with impaired growth. Although primary aldosteronism is a rare occurrence in children, the condition appears to deserve special attention not only from the viewpoint of growth failure and hypokalaemia but from the occurrence of late organ damage to the kidney and heart.

Evaluation of adrenal function in patients with growth hormone deficiency and hypothalamic-pituitary disorders: comparison between insulin-induced hypoglycemia, low-dose ACTH, standard ACTH and CRH stimulation tests

OBJECTIVES

Patients with organic growth hormone deficiency (GHD) or with structural hypothalamic-pituitary abnormalities may have additional anterior pituitary hormone deficits, and are at risk of developing complete or partial corticotropin (ACTH) deficiency. Evaluation of the integrity of the hypothalamic-pituitary-adrenal axis (HPA) is essential in these patients because, although clinically asymptomatic, their HPA cannot appropriately react to stressful stimuli with potentially life-threatening consequences.

DESIGN AND METHODS

In this study we evaluated the integrity of the HPA in 24 patients (age 4.2-31 years at the time of the study) with an established diagnosis of GHD and compared the reliability of the insulin tolerance test (ITT), short synacthen test (SST), low-dose SST (LDSST), and corticotropin releasing hormone (CRH) test in the diagnosis of adrenal insufficiency.

RESULTS

At a cortisol cut-off for a normal response of 550 nmol/l (20 microg/dl), the response to ITT was subnormal in 11 subjects, 6 with congenital and 5 with acquired GHD. Four patients had overt adrenal insufficiency, with morning cortisol concentrations ranging between 66.2-135.2 nmol/l (2.4-4.9 microg/dl) and typical clinical symptoms and laboratory findings. In all these patients, a subnormal cortisol response to ITT was confirmed by LDSST and by CRH tests. SST failed to identify one of the patients as adrenal insufficient. In the seven asymptomatic patients with a subnormal cortisol response to ITT, the diagnosis of adrenal insufficiency was confirmed in one by LDSST, in none by SST, and in five by CRH tests. The five patients with a normal cortisol response to ITT exhibited a normal response also after LDSST and SST. Only two of them had a normal response after a CRH test. In the seven patients with asymptomatic adrenal insufficiency mean morning cortisol concentration was significantly higher than in the patients with overt adrenal insufficiency. ITT was contraindicated in eight patients, and none of them had clinical symptoms of overt adrenal insufficiency. One of these patients had a subnormal cortisol response to LDSST, SST, and CRH, and three exhibited a subnormal response to CRH but normal responses to LDSST and to SST.

CONCLUSION

We conclude that none of these tests can be considered completely reliable for establishing or excluding the presence of secondary or tertiary adrenal insufficiency. Consequently, clinical judgment remains one of the most important issues for deciding which patients need assessment or re-assessment of adrenal function.

Evaluation of anterior pituitary gland volume in childhood using three-dimensional MRI

BACKGROUND

Three-dimensional MRI (3D-MRI) is a reliable tool for the evaluation of anatomical volumes. Volumetric measurement of the normal anterior pituitary gland in childhood has been performed in the past by 2D-MRI calculations, but has inherent inaccuracies.

OBJECTIVE

To obtain accurate normal anterior pituitary gland volume in childhood using 3D-MRI coronal sections.

MATERIALS AND METHODS

The anterior pituitary gland was measured using coronal T1-weighted 3D-gradient-echo sequences (section thickness 0.75 mm). The study group was composed of 95 prepubertal children (age range 2 months-10 years) with clinically normal pituitary function and no pituitary or brain abnormalities.

RESULTS

A measurement error of 0.2-0.4% was assessed by using a phantom study. Volumetric evaluation of the anterior pituitary gland showed progressive growth of the gland from a mean 131+/-24 mm(3) at 2-12 months, to 249+/-25 mm(3) at 1-4 years and 271+/-29 mm(3) at 5-10 years.

CONCLUSIONS

These data may be useful for paediatricians in the evaluation of patients with neuroendocrine diseases, in particular growth hormone deficiency.

Magnetic resonance imaging of the hypothalamus-pituitary unit in childrensuspected of hypopituitarism: who, how and when toinvestigate

The magnetic resonance (MR) identification of pituitary hyperintensity in the posterior part of the sella has been the most striking recent finding contributing to the diagnosis of "idiopathic" and permanent GH deficiency (GHD). Moreover, advancements in DNA technology have shed new light on the study of the genetic causes of hypopituitarism. Abnormalities in two genes, the GH-N encoding the GH and the GHRH receptor (GHRH-R), have been identified, while mutations in five other gene-encoding transcription factors such as Pit-1, Prop-1, Hesx-1, Lhx-3 and Lhx-4 involved in anterior pituitary development, have also been described. MR imaging shows marked differences in pituitary morphology indicating different GHD etiologies and different prognoses. Ectopic posterior pituitary is a specific marker of permanent GHD. These patients do not have Pit-1, Prop-1, or Lhx-3 mutations and should be carefully monitored for evolving pituitary hormone defects, though they do not require GH re-evaluation in adulthood; selected cases may have Hesx-1 or Lhx-4 mutations. MR evidence of normal or small anterior pituitary gland, enlarged empty sella, pituitary hyperplasia and/or intrasellar or suprasellar mass when associated with combined pituitary hormone deficiency call for molecular analysis of Pit-1, Prop-1, Hesx-1, or Lhx-3. Limitation of neck rotation and Chiari-I malformation may suggest Lhx-3 or Lhx-4 mutations (exceedingly rare). In "idiopathic" isolated GHD, evidence of normal anterior or small anterior pituitary size with normal location of posterior pituitary and normal connection between the hypothalamus and pituitary gland is suggestive of "transitory" or false positive GHD; patients with such characteristics should be re-evaluated well before reaching adult height. In selected cases, anterior pituitary height that is 2 SD below age-adjusted normal pituitary height could be suggestive of GHRH-R gene defect; it is worth pointing out that normal pituitary MR together with severe GHD has been observed, though rarely, in subjects with a genetic origin of GHD.

MRI findings of the pituitary gland in short children born small for gestational age (SGA) in comparison with growth hormone-deficient (GHD) children and children with normal stature

BACKGROUND

Disturbances in the GH/IGF-I axis are reported in 25-60% of short children born small for gestational age (SGA). We hypothesized that these abnormalities might be related to abnormalities in the pituitary region. Therefore, the results of magnetic resonance imaging (MRI) of short SGA children were compared to MRI results of other groups of short children and to normal controls.

PATIENTS AND METHODS

MRI was performed in four groups of short children: SGA children without GH deficiency (SGA group; n = 17), SGA children with isolated GH deficiency (SGA + IGHD group; n = 10), non-SGA children with isolated GH deficiency (IGHD group; n = 24) and non-SGA children with multiple pituitary hormone deficiencies (MPHD group; n = 15). MRI was also performed in children with normal stature (control group; n = 13). Pituitary height (PH) and thickness of the pituitary stalk (PS) were measured and their relationship with the maximum GH peak during a GH stimulation test, serum IGF-I and IGFBP-3 levels was evaluated.

RESULTS

Short SGA children either with or without IGHD did not show major anatomical abnormalities in the hypothalamic-pituitary region in contrast to 58% of the non-SGA IGHD children and 87% of the MPHD children who had anatomical abnormalities. PH in SGA children without GHD was normal whereas it was significantly lower in SGA children with IGHD. The lowest PHs were measured in non-SGA children with MPHD. A moderate decrease in PH was associated with significantly lower maximum serum GH peaks and lower serum IGF-I and IGFBP-3 levels.

CONCLUSION

Measuring PHs in children with less severe GHD, who underwent MRI as part of the diagnostic process, might support the diagnosis of GHD even in the absence of anatomical abnormalities. Our study demonstrates that there is no indication to perform MRI of the pituitary region in short children born SGA without GHD.

The spectrum of hypopituitarism caused by PROP1 mutations

Mutations in the PROP1 gene are responsible for a high proportion of cases of multiple or combined anterior pituitary hormone deficiencies in humans. The physical and hormonal phenotypes of affected individuals are not uniform. The diagnosis is seldom considered during the first year of life. Growth failure is usually evident later in childhood. Deficiency of growth hormone (GH) tends to precede deficiency of thyroid-stimulating hormone (TSH). While most affected individuals fail to enter puberty without sex hormone replacement, some enter puberty but then develop pubertal arrest with a loss of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) responses to GnRH. Partial deficiency of corticotrophin (ACTH) is a late finding. Imaging of the pituitary may disclose either a small anterior pituitary gland or an intrapituitary mass. The mechanisms responsible for delayed loss of hormone production and the occasional overgrowth of the pituitary represent important areas for future research.

Height velocity and IGF-I assessment in the diagnosis of childhood onset GH insufficiency: do we still need a second GH stimulation test?

OBJECTIVE

The diagnosis of GH insufficiency (GHI) in childhood is not straightforward. Our aim was to test the sensitivity and specificity of height velocity (HV), IGF-I, IGFBP-3 and GH stimulation tests alone or in combination in the diagnosis of GHI.

DESIGN

A retrospective review of patients with GHI and idiopathic short stature (ISS) diagnosed in our centre and followed up to the completion of linear growth.

PATIENTS

Thirty-three GHI children and 56 children with ISS were evaluated. GHI diagnosis was based on fulfilment of anthropometric, endocrine and neuroradiological criteria: stature < or = -2 z-score, delayed bone age (at least 1 year), GH peak response to at least two different provocative tests < 10 micro g/l (20 mU/l), brain MRI positive for hypothalamus-pituitary abnormalities, catch-up growth during the first year of GH replacement therapy > or = 75th centile, peak GH response to a third provocative test after growth completion < 10 micro g/l (20 mU/l). Children with anthropometry resembling that of GHI but with peak GH responses > 10 micro g/l (20 mU/l) were diagnosed as ISS.

MEASUREMENTS

All subjects underwent standard anthropometry. GH secretory status was assessed by clonidine, arginine and GHRH plus arginine stimulation tests. IGF-I and IGFBP-3 circulating levels were measured by immunoradiometric assay (IRMA). The following cut-off values were chosen to discriminate between GHI and nonGHI short children: HV < 25th centile over the 6-12 months prior to the initiation of GH therapy, peak GH responses < 10 or < 7 micro g/l (< 20 or < 14 mU/l) and IGF-I and IGFBP-3-values < -1.9 z-score. Sensitivity (true positive ratio) and specificity (true negative ratio) were evaluated.

RESULTS

Taking 10 micro g/l (20 mU/l) as the cut-off value, sensitivity was 100% and specificity 57% for GH provocative tests, whereas taking 7 as the cut-off value, sensitivity was 66% and specificity rose to 78%. Sensitivity was 73% for IGF-I and 30% for IGFBP-3 measurement, whilst specificity was 95% for IGF-I and 98% for IGFBP-3 evaluation. HV assessment revealed a sensitivity of 82% and a specificity of 43%. When HV and IGF-I evaluations were used in combination, sensitivity reached 95% and specificity 96%. When both HV and IGF-I are normal (26% of our subjects) GHI may be ruled out, whereas when both the indices are subnormal (23%) GHI is so highly likely that the child may undergo only one GH provocative test and brain MRI and, thereafter, may begin GH therapy without any further test. In case of discrepancy, when IGF-I is normal and HV < 25th centile (44% of children), due to the relatively low sensitivity of IGF-I assessment and low specificity of HV, the patient should undergo GH tests and brain MRI. Finally, in the rare case of HV > 25th centile and subnormal IGF-I-values (7%), due to the high specificity of IGF-I measurement, the child should undergo one provocative test and brain MRI for the high suspicion of GHI.

CONCLUSIONS

Our results suggest that a simple assessment of HV and basal IGF-I may exclude or, in association with only one stimulation test, confirm the diagnosis of GH insufficiency in more than half of patients with short stature.

Late onset of adrenocortical failure in GH deficiency with invisible pituitary stalk: a case report of a 48-year-old Japanese man and review of the literature

ACTH deficiency gradually develops in patients with growth hormone deficiency (GHD) who have abnormalities of the pituitary stalk on magnetic resonance imaging (MRI) following perinatal complications. We report here a rare case of GHD manifesting ACTH deficiency in middle age. A 48-year-old male patient was admitted to our hospital due to fever and hyponatremia. He was diagnosed as GHD and hypothyroidism at the age of 9, and had received lysine treatment until age 20, which was then replaced by thyroid hormone. He was not mentally retarded, but was the shortest in his class throughout his schooldays, reaching a final height of 148 cm. Hormonal examination revealed the presence of hypoadrenalism as indicated by poor responses of plasma cortisol to intravenous administration of corticotropin-releasing hormone (CRH) and insulin-induced hypoglycemia. Plasma ACTH responded well to CRH, but not to insulin-induced hypoglycemia, indicating that his hypoadrenalism was of hypothalamic origin. MRI showed an invisible pituitary stalk and relatively small pituitary gland. Since he had a perinatal abnormality, the damage around the pituitary and GHD could have originated from birth. In the literature, around 60% of GHD patients with pituitary stalk abnormalities develop hypoadrenalism due to ACTH deficiency, and more than 90% of such cases are diagnosed by age 30. We suggest that the appearance of hypoadrenalism should be carefully monitored in GHD patients with pituitary stalk abnormalities even after they reach middle age.

Diagnostic value of pituitary MRI in differentiation of children with normal growth hormone secretion, isolated growth hormone deficiency and multiple pituitary hormone deficiency

Pituitary height, volume and morphology were investigated by MRI in patients aged 3.5-24.9 years with growth hormone deficiency (GHD) in relation to birth history and hormonal findings. Three groups with comparable age, sex and pubertal stage were studied: group I (n=42)--patients with isolated growth hormone deficiency (IGHD); group II (n=22)-- patients with multiple pituitary hormone deficiency (MPHD); and group III (n=30)--healthy controls. Pituitary height and volume differed significantly between the three groups, with the smallest in group II and largest in group III (p <0.001 for both). Both variables correlated significantly with peak GH value in the patient groups (p <0.001). The specificity of pituitary dysmorphology in the determination of GHD was 100% and its sensitivity in differentiation of IGHD and MPHD was 95%. Ectopic neurohypophysis was present in 75% of breech births and 27% of head-presenting patients (p <0.01). This study emphasizes the differential diagnostic value of pituitary MRI and its contribution to the understanding of the pathogenesis and prognosis in GHD.

Magnetic resonance imaging of the hypothalamic-pituitary axis in the diagnosis of growth hormone deficiency

In order to investigate the relationship between pituitary appearance and the diagnosis of growth hormone deficiency (GHD), we have assessed magnetic resonance imaging (MRI) scans and GH status during provocation tests in 110 patients (78 males; median age 9.8, range 0.1-20 yr), evaluated for possible GH disorders. On the basis of pituitary function tests, patients were divided into GH deficient (GH peak < 15 mIU/l [5.8 ng/ml]) (n = 82) or GH sufficient (GH peak > 15 mIU/l) (n = 28). The former were further divided into those with multiple hormone deficits (MPHD) (n = 19) or isolated GHD - severe IGHD (peak GH < 8 mIU/l [3.1 ng/ml]) or partial IGHD (8-15 mIU/l). The appearance of the hypothalamic-pituitary (H-P) axis was classified as: (1) normal, (2) isolated hypoplastic stalk (HPS), (3) isolated hypoplastic anterior lobe (HPAL) (PHT SDS < -2.0), (4) HPS + HPAL or (5) ectopic posterior lobe (EPL). The last two were considered severe abnormalities. PHT SDS (mean +/- SD -2.0 +/- 2.2) was correlated to log peak GH levels in the whole group (r = 0.45; p < 0.0001) and in the GHD group (r = 0.39; p < 0.0001). Sixty-five out of 82 in the GHD group had a H-P axis abnormality (45 severe abnormalities), while 13 out of the 28 patients in the GH sufficient group also had an abnormality (3 severe, but none with an EPL). All patients with MPHD had a MRI abnormality, most commonly an EPL (79%). Thus the presence of any MRI abnormality as a marker for GHD would generate a sensitivity of 79%, but a specificity of only 54%, indicating that this could not be used to confirm GHD. However, the presence of either an EPL or HPS + HPAL on MRI is highly specific (100% and 89% respectively) and predictive of GHD (positive predictive value 100% and 79% respectively), indicating that these abnormalities provide confirmation of the diagnosis. We recommend that if clinical, auxological and biochemical data indicate a diagnosis of GHD, then a MRI scan should be undertaken to define the pituitary anatomy and to help confirm the diagnosis.

Posterior pituitary ectopy in children with idiopathic growth hormone deficiency

AIMS

To evaluate the underlying pathogenesis in children with pituitary hormone deficiency by means of high resolution MRI of the brain.

PATIENTS/METHODS

Thirty-seven children with short stature and isolated GH deficiency (IGHD, n = 17) or multiple pituitary hormone deficiency (MPHD, n = 20) were subjected to an MRI of the brain at the age of 1.0-17.3 years. The anatomic condition of the hypothalamo-pituitary area was analyzed and the height of the pituitary gland was measured and compared to the data of age-matched healthy subjects.

RESULTS

Seventy percent of the patients had a characteristic anomaly: the adenohypophysis was hypoplastic, the infundibulum was absent and the posterior pituitary lobe was ectopic at the bottom of the median eminence. The height of the anterior pituitary was significantly reduced in these patients (1.9 +/- 0.1 mm; mean +/- SD) when compared to age-matched healthy controls (4.1 +/- 0.8 mm, p<0.001) or hypopituitary patients with a normal MRI (4.3 +/- 0.8 mm). MPHD was found in 62% of patients with the pituitary anomaly whereas only 27% of children with a normal MRI had MPHD (p<0.05).

CONCLUSIONS

The pathogenesis of the pituitary anomaly is unknown; a disorder during embryonal development or perinatal events have been discussed as causal factors. MRI should have a prominent position in the work-up of hypopituitary children. When an anatomical malformation is visualized by MRI, the diagnostic terminology should be adapted accordingly.

Sequential contrast-enhanced magnetic resonance imaging in the diagnosis of growth hormone deficiencies

The purpose of the present study was to assess the presence and the time-course of contrast-enhancement in the pituitary gland and pituitary stalk of 24 patients with isolated growth hormone (GH) deficiency and multiple pituitary hormone deficiency. The patients were evaluated clinically (auxological measurements), endocrinologically (spontaneous GH secretion and GH stimulation tests) and with conventional MRI scans. In addition, fast-framing dynamic magnetic resonance imaging (MRI) with Gd-DTPA enhancement was used to quantitate the time course of contrast enhancement within the neurohypophysis, pituitary stalk, postero-superior adenohypophysis and antero-inferior adenohypophysis. In 3 patients without evidence of abnormalities at normal conventional MRI scans (normal anterior lobe and pituitary stalk, normal posterior lobe) and a high response to the GRF provocation test, sequential time-resolved Gd-enhanced MRI demonstrates reduced contrast enhancement in the pituitary stalk. These findings are consistent with impairment in stalk vasculature, presumably located at the level of the portal venous system, and could play a role in the pathogenesis of pituitary hormonal deficiency.

Hypothalamic Peptides in Human Brain Diseases

The human hypothalamus is subdivided into some 20 well-defined nuclei that have a multitude of specific functions from the time of birth to the moment we die. Hypothalamic nuclei show structural and functional differences not only in relation to classic neuroendocrine disorders, such as diabetes insipidus, climacteric flushes and Kallman's syndrome, but also in relation to gender and sexual orientation, to adaptive processes such as non-thyroidal illness and in psychiatric disorders such as depression.

Hypopituitarism in Two Brothers Born by Breech Delivery

OBJECTIVE

To describe two brothers with hypopituitarism who had been born by breech delivery and to discuss whether this condition corresponds to a familial form or to a pituitary stalk section as a result of the breech delivery.

METHODS

We present the clinical, biochemical, and magnetic resonance imaging (MRI) characteristics of two Mexican brothers, 19 and 21 years old, with hypopituitarism and a history of breech delivery.

RESULTS

Physical examination of both patients showed short stature with normal body proportions, an obviously younger appearance than that expected for their chronologic age, high-pitched voice, irregularly positioned teeth, no axillary or pubic hair, and prepubertal genitalia. Biochemical testing showed low thyroxine and free thyroxine values with inadequate or normal thyrotropin, low basal testosterone, and mildly increased serum prolactin levels. Stimulation tests showed a normal and a delayed thyrotropin response to thyrotropin-releasing hormone, subnormal serum cortisol, considerably blunted growth hormone (GH) response to insulin-induced hypoglycemia, and absence of GH response to GH-releasing hormone in both cases. MRI showed an ectopic neuropituitary gland. In case 1, a caudal portion of a very thin pituitary stalk was observed, suggesting the preservation of a vascular component of the stalk. Because both parents of these brothers shared the major histocompatibility complex haplotype HLA-A*2301, B*3501, DRB1*0407, DQA1*03, DQB1*0201, consanguinity was suggested.

CONCLUSION

The phenotype of these patients differs from that described in families with POU1F1 (Pit-1) and PROP1 mutations. These cases are most likely related to an autosomal recessive gene mutation that warrants further research. To our knowledge, this is the first report of hypopituitarism in two brothers born by breech delivery.

Growth hormone (GH) deficiency (GHD) of childhood onset: reassessment of GH status and evaluation of the predictive criteria for permanent GHD in young adults

GH secretion was reevaluated after completion of GH treatment at a mean age of 19.2 +/- 3.2 yr in 35 young adults with childhood-onset GH deficiency (GHD). The patients were subdivided into 4 groups according to their first pituitary magnetic resonance imaging (MRI) findings: group I, 11 patients with isolated GHD (IGHD) and normal pituitary volume (280 +/- 59.4 mm3); group II, 7 patients with IGHD and small pituitary gland (163.1 +/- 24.4 mm3; P = 0.0009 vs. group I); group III, 13 patients (5 with IGHD and 8 with multiple pituitary hormone deficiency) with congenital hypothalamic-pituitary abnormalities such as pituitary hypoplasia (95.8 +/- 39.3 mm3; P < 0.00001 vs. group I and P = 0.003 vs. group II), pituitary stalk agenesis, and posterior pituitary ectopia; and group IV, 4 patients with multiple pituitary hormone deficiency secondary to craniopharyngioma. Pituitary MRI and GH secretory status were reevaluated after GH withdrawal using arginine, insulin induced-hypoglycemia, and sequential arginine-insulin tests. Serum insulin-like growth factor I (IGF-I) and IGF-binding protein-3 (IGFBP-3) were determined at the time of retesting and 6, 12, and 24 months after discontinuation of treatment in the patients with permanent GHD and after 6 months in those with normal GH responses to stimulation. The patients in groups I and II showed a normal response to stimulation after completion of GH treatment regardless of pituitary size, whereas all patients in groups III and IV still had a GH response of less than 3 microg/L to any of the tests. Pituitary volume normalized in 6 of 7 patients in group II, whereas in all patients in group III MRI studies confirmed the initial findings. Mean IGF-I and IGFBP-3 concentrations at the time of retesting were significantly higher in groups I and II than in groups III and IV. In patients of groups III and IV, mean IGF-I was significantly decreased after 6 and 12 months, whereas IGFBP-3 was significantly decreased 12 months after treatment withdrawal. Our results confirm that a high proportion of children with IGHD and normal or small pituitary show normalization of GH secretion at the completion of GH treatment, whereas GHD is permanent in all patients with pituitary hypoplasia, pituitary stalk agenesis, and posterior pituitary ectopia. IGF-I and IGFBP-3 determinations shortly after GH withdrawal had limited value in the diagnosis of GHD of childhood onset associated with congenital hypothalamic-pituitary abnormalities, but became accurate after 6-12 months. We suggest that patients with GHD and congenital hypothalamic-pituitary abnormalities do not require further investigation of GH secretion, whereas patients with IGHD and normal or small pituitary gland should be retested well before the attainment of adult height.

The human hypothalamo-neurohypophysial system in health and disease

The present paper reviews the changes observed in the human supraoptic (SON) and paraventricular (PVN) nuclei, and their projections to the neurohypophysis, median eminence and to other brain areas in health and disease.

Failure to increase insulin-like growth factor-I synthesis is involved in the mechanisms of growth retardation of children with inherited liver disorders

OBJECTIVE

Growth retardation is a prominent secondary feature of chronic liver disease. We investigated the hypothalamic-pituitary-liver axis in six patients with inherited liver disease and growth failure. The objectives were to determine (1) whether there were any abnormalities in the GH/IGF-I/IGFBPs/GH binding protein (GHBP) axis, (2) whether any abnormalities were nutrition-dependent, and (3) whether recombinant human (rh) GH could be efficaciously and safely administered.

MEASUREMENTS

The evaluation included two standard GH provocative tests, GHRH test, night-time GH secretion, GHBP; and IGF-I, IGFBP-3 and IGFBP-1 before and after 0.1 and 0.3 U/kg/day of rhGH given i.m., for 4 days. Two patients were enrolled for rhGH treatment.

RESULTS

Quantitative nutritional assessment showed the patients' calorie and protein intake to be compatible with the recommended daily allowance in liver disease. The mean baseline GH level was higher in patients than in controls (8.4 +/- 3.8 vs 2.6 +/- 2.0 mU/l, P < 0.005) and the GH response to stimuli was normal; spontaneous GH secretion was apparently normal. The mean baseline IGF-I value in the patients was significantly below the mean of controls (31.6 +/- 16.4 vs 260 +/- 35.2 micrograms/l, P = 0.00001) and similar to that of children with GH-deficiency (40.8 +/- 18.4 micrograms/l). The mean peak IGF-I response after 0.1 U/kg/day of rhGH increased (84.9 +/- 28.2 micrograms/l, P = 0.009) but remained lower than the mean IGF-I response in GH-deficient patients and in controls (P = 0.00001). The mean peak IGF-I response after 0.3 U/kg/day (113.3 +/- 52.3 micrograms/l) was significantly higher than that after 0.1 U/kg/day (P = 0.002). The mean standard deviation score (SDS) peak for IGF-I response to 0.1 and 0.3 U/kg/day of rhGH decreased significantly from -1.7 to -1.0 (P = 0.02) and from -1.9 to -0.9 (P = 0.005), respectively. There was no difference between patients and controls in serum GHBP activity or in mean baseline IGFBP-3 and IGFBP-1 levels. IGFBP-3 levels did not change significantly in response to rhGH at either 0.1 or 0.3 U/kg/day, while IGFBP-1 significantly decreased after 0.3 U/kg/day (56.3 +/- 35.6 vs 45.9 +/- 33.1 micrograms/l, P = 0.04). A significant positive correlation was present between albumin and peak IGF-I responses to rhGH at the dose of 0.1 and 0.3 U/kg/day (R = 0.83, P = 0.03; R = 0.78, P = 0.03 respectively), as well as between height SDS and baseline or stimulated IGF-I after rhGH 0.1 U/kg/day (R = 0.81, P = 0.04; R = 0.88, P = 0.01 respectively). In the two patients treated with rhGH at 22-25 U/m2/week, the growth rate doubled in one and trebled in the other during the first year of treatment, and in both was maintained in the second year without acceleration of bone maturation or evidence of adverse effects.

CONCLUSIONS

The underlying cause of growth retardation in patients with inherited liver disease seems to be a progressive failure to increase IGF-I synthesis (at the conventional rhGH dose) and the consequent lack of its growth-promoting effect. The moderate increase in baseline GH values, the greater IGF-I response to the higher rhGH dose and the improvement in growth rate following rhGH administration suggest at least a degree of sensitivity to rhGH which could be of therapeutic value.

[Pituitary stalk transection syndrome]

BACKGROUND

Pituitary stalk transection is a non-negligible cause of growth hormone (GH) deficiency.

POPULATION AND METHODS

We studied 22 children (13 boys, nine girls) aged at the first clinical manifestations from 2 days to 10 years (average = 5.33 +/- 2 years). Pituitary stalk transection was assessed by the means of magnetic resonance imaging (MRI). The children's past history showed fetal distress in 12 cases (54.5%), cranial trauma in three (13%) and a midline anomaly in three (13%). The first clinical manifestations were neonatal hypoglycemia (two cases), decreased growth velocity (18 cases) and diabetes insipidus (two cases).

RESULTS

GH deficiency was complete, present from the onset in 19 of 22 cases and isolated in four. Fifteen of 22 cases had adreno-corticotrophic hormone (ACTH) and thyroid stimulating hormone (TSH) deficiency. Diabetes insipidus was present in six cases and revealed the syndrome in two. All children older than normal age of puberty (n = 10) had gonadotropin deficiency. In our study, these hormonal anomalies progressed from isolated GH deficiency to multiple hormonal deficiencies.

CONCLUSION

The recently described stalk transection syndrome is relatively frequent and should be suspected after cranial trauma or fetal distress syndrome. The outcome is progressive evolution towards panhypopituitarism and these patients require regular clinical survey and hormonal controls.

Perfusion MRI in normal and abnormal pituitary gland. A preliminary study

Perfusion MRI (magnetic resonance imaging) of the pituitary gland was performed in 20 healthy volunteers and 63 patients with various lesions involving the pituitary gland. All patients underwent sequential contrast-enhanced MRI using spoiled gradient recalled sequences with high temporal resolution (7 seconds). Four pituitary areas (pituitary stalk, posterior lobe, postero-superior, and antero-inferior adenohypophysis) were tested with a selected region of interest. Maximal contrast percentual variation was calculated. The timing of enhancement in normal patients matched perfectly with normal pituitary vascularization. Abnormal timing in pathological condition was investigated.

Is the persistence of isolated GH deficiency in adulthood predicted by anatomical hypothalamic-pituitary alterations?

The aim of this study was to verify the persistence in adulthood of GH deficiency diagnosed in childhood and treated with hGH in childhood and to study whether anatomical hypothalamic-pituitary alterations evaluated by magnetic resonance (MR) imaging could predict it. To this goal, in six GHD adults (3 males and 3 females aged 17.2-24.5 yr, BMI 21.8 +/- 1.3), we studied anterior pituitary hormone response to GHRH (1 microgram/kg iv)+pyridostigmine (120 mg po)+ GnRH (100 micrograms iv) +TRH (400 micrograms iv)+hCRH (100 micrograms iv) as well as brain MR imaging. In childhood, the diagnosis of severe isolated GHD had been done based on auxological findings as well as on GH response < 7 micrograms/L after two classical provocative stimuli. In the present study, hormonal responses showed the persistence of severe isolated GHD in 4 out of 6 patients (peak, mean +/- SEM: 3.8 +/- 0.6, range 2.6-4.8 micrograms/L). In these patients, IGF-I levels were found low or low-normal. In other 2 patients, a clear GH response to stimulation (peak: 51.3 and 43.0 micrograms/L, respectively) together with normal IGF-I levels were found. No other anterior pituitary hormone deficiency was present in all subjects. MR imaging showed pituitary hypoplasia in all patients with persistent GHD; in 2 out of them, pituitary stalk interruption and ectopic neurohypophysis was also present. On the other hand, MR imaging showed normal hypothalamo-pituitary morphology in the 2 subjects with normal somatotrope response. In conclusion, our present data indicate that testing with a potent stimulus such as GHRH+pyridostigmine is a reliable method to assess the persistence of GH deficiency which associates with anatomical hypothalamic-pituitary alterations at the MR imaging. Patients with transient GH deficiency in childhood and normal pituitary GH reserve in adulthood have normal hypothalamic-pituitary MR imaging.