High Resolution CT Scanning of the Pituitary Gland in Growth Disorders

ABSTRACT. We have performed 217 GEC 8800 CT scans of the hypothalamus and pituitary glands of 202 children with disorders of growth and development. Pituitary morphological abnormalities were common. Intrapituitary low density lesions were found in 17 % of the whole series and in 58% of children with tall stature. Seventy-seven children with idiopathic growth hormone deficiency could be divided on the basis of pituitary morphology seen on CT scan into pituitary aplasia (n = 11) and pituitary hypoplasia (n = 53). Patients with pituitary aplasia had an absent adenohypophysis which probably dated from early intrauterine life and therefore could not be related to birth trauma. We have found a high incidence of evolving endocrinopathy in children with pituitary insufficiency: thus, if a short child is investigated the initial endocrine findings need to be repeated as the pattern of pituitary insufficiency changes with time. An evolving endocrinopathy starting in later childhood is suggestive of the presence of a cerebral tumour. Children with subnormal growth velocities and a normal growth hormone response to pharmacological tests have a wide spectrum of pituitary morphological abnormalities which may be associated with growth hormone neurosecretory dysfunction.     

Hypopituitarism and neurodevelopmental abnormalities in relation to central nervous system structural defects in children with optic nerve hypoplasia

OBJECTIVE: Optic nerve hypoplasia (ONH) is a heterogeneous disease with variable findings of pituitary insufficiency, CNS and neurodevelopmental abnormalities. We characterized the spectrum of endocrinopathy in a cohort of children with ONH and attempted to correlate the presence of different midline CNS findings with the degree of hypopituitarism. The correlation of variable CNS abnormalities with the presence of a seizure disorder and neurodevelopmental delay was also examined. METHODS: Charts of 56 patients with ONH referred to our endocrine clinics between 1990 and 2000 were reviewed. Neurodevelopmental assessment was based on questionnaires sent to families during the study period. RESULTS: Forty-six patients (82%) had hypopituitarism, with growth hormone deficiency being the most common endocrinopathy. All patients with diabetes insipidus, hypocortisolism, and hypogonadotropin hypogonadism also had combined pituitary hormone deficiency. Evolving pituitary hormone deficiency was observed in two of 37 patients diagnosed with hypopituitarism in the first 3 years of life. No single midline CNS finding correlated with the presence of hypopituitarism or a seizure disorder. However, hydrocephalus or a seizure disorder was more commonly seen in patients with developmental delay. CONCLUSION: ONH is a heterogeneous disorder with possible multifactorial etiologies. All patients with this diagnosis deserve a comprehensive endocrine and neurodevelopmental evaluation.     

Growth hormone deficiency in patients with 22q11.2 deletion: expanding the phenotype

The list of findings associated with the 22q11.2 deletion is quite long and varies from patient to patient. The hallmark features include: conoruncal cardiac anomalies, palatal defects, thymic aplasia or hypoplasia, T cell abnormalities, mild facial dysmorphia, and learning disabilities. The 22q11.2 deletion has been seen in association with the DiGeorge sequence, velocardiofacial syndrome (VCFS), conotruncal anomaly face syndrome, isolated conotruncal cardiac anomalies, and some cases of autosomal dominant Optiz G/BBB syndrome. Short stature has been seen in one to two thirds of children reported in the literature with a diagnosis of VCFS, but growth hormone deficiency (GHD) has not been described in conjunction with this diagnosis. We present 4 patients with a 22q11.2 deletion and short stature who were found to have abnormalities in the growth hormone-insulin-like growth factor I axis. All had growth factors less than -2 SD for age and failed provocative growth hormone testing. Two patients were found to have abnormal pituitary anatomy. In our population, the incidence of GHD in 4 or 95 children with 22q11 deletion is significantly greater than the estimated incidence of GHD in the general population. Children with a 22q11.2 deletion appear to be at a greater risk for pituitary abnormalities. Therefore, those children with the 22q11.2 deletion and short stature or poor growth should be evaluated for GHD, as replacement growth hormone therapy may improve their growth velocity and final height prediction.     

Endocrinological and auxological abnormalities in young children with optic nerve hypoplasia: a prospective study

OBJECTIVE: To determine the prevalence of endocrinopathies, neuroradiographical findings, and growth derangements in young children with optic nerve hypoplasia (ONH). STUDY DESIGN: A prospective observational study examined the prevalence of endocrinopathies at study enrollment and growth patterns in children with ONH. Subjects (n = 47, mean +/- SD 15.2 +/- 10.6 months) were followed until 59.0 +/- 6.2 months of age. RESULTS: The prevalence of endocrinopathies was 71.7%: 64.1% of subjects had growth hormone (GH) axis abnormalities, 48.5% hyperprolactinemia, 34.9% hypothyroidism, 17.1% adrenal insufficiency, and 4.3% diabetes insipidus (DI). Endocrinopathies were not associated with ONH laterality, absence of the septum pellucidum, or pituitary abnormalities on neuroimaging. End height standard deviation score (SDS) was similar to start length SDS independent of GH surrogate status. A significant increase in end weight SDS was found for the cohort (p < .001). A body mass index (BMI) >85th percentile was noted in 44.4% of the cohort and in 52.1% of subjects with GH axis abnormalities. Initial hyperprolactinemia was positively associated with increased end BMI SDS (p = .004). CONCLUSIONS: These prospective findings confirm the high prevalence of pituitary endocrinopathies in children with ONH reported in previous retrospective studies. Our data reveal that some of these children maintain normal height velocity despite GH axis abnormalities, and, as a group, they are at high risk for increased BMI.     

Endocrine disorders in septo-optic dysplasia (De Morsier syndrome) — evaluation and follow up of 18 patients

Septo-optic dysplasia (SOD) is characterized by hypoplasia of the optic nerve, various types of forebrain defects and hormonal deficiencies. We have studied the clinical and endocrinological characteristics of 18 such patients retrospectively to: (1) better define the endocrine abnormalities in children with SOD; and (2) to find approaches for the interdisciplinary long-term care of children with SOD. The children were seen at the Children's Hospital of the University of Munich from 1976 to 1992 (8 boys, 10 girls; age at initial presentation: 1 day–13 years of age, mean 1.9 years). Unilateral hypoplasia of the optic nerve was found in 7 cases, bilateral hypoplasia in 11. Sonographic, CCT or MRI yielded the following results: 4 of the patients had a cavum septum pellucidum, 3 patients had hypoplasia of the cerebellum, 1 aplasia of the corpus callosum and 1 aplasia of the fornix. An empty sella with or without an ectopic pituitary was seen in 4 cases. Height standard deviation score (SDS) at time of diagnosis was –4.0 to +0.4, mean –2.92. Endocrine deficiencies were present in all 11 patients who had undergone endocrinological investigations. Seven patients suffered from isolated growth hormone (GH) deficiency or multiple hypopituitarism. One had diabetes insipidus centralis, 2 had hypogonadotropic hypogonadism, 1 had hypothyroidism and 2 adrenal insufficiency. Hypothalamic testing was performed only in a subset of patients: in 5 of 11 children tested a thyrotropin releasing hormone (TRH test), in two out of nine a gonadotropin releasing hormone (GnRH) test, and in three out of six GH releasing hormone (GHRH) test yielded abnormal results. High prolactin levels were measured in two out of five patients.Conclusion SOD is characterized by optic nerve hypoplasia and a variety of endocrine deficiencies. In addition, forebrain malformations are present in most SOD patients. Hormonal disorders are present in some SOD patients which may be of hypothalamic origin and need to be investigated systematically.     

Clinico-radiological correlation in childhood hypopituitarism

Non-tumor etiology constitutes a major group of childhood hypopituitarism. Magnetic resonance imaging has enormously complimented hormonal assessment in these patients. We describe clinico-radiological correlates in thirtyone children (23 boys), aged 1–17 years with a peak GH (growth hormone) levels <7 ng/mL after pharmacological stimuli. Hypoplastic pituitary gland was the most frequent abnormality in children with isolated growth hormone deficiency (IGHD) as compared to stalk abnormalities in children with multiple pituitary hormone deficiencies. MRI tetrad (hypoplastic/absent pituitary, hypoplastic stalk, absent/ectopic posterior pituitary bright spot and empty sella) was more prevalent in IGHD. MRI abnormalities correlated with the severity of growth hormone deficiency.     

Hypothalamo-pituitary-adrenal axis integrity after cranial irradiation for childhood posterior fossa tumours

BACKGROUND: The evolution of anterior pituitary deficits after treatment for pituitary tumours has been largely attributed to local irradiation, but may be influenced as much by tumour mass or surgery. Other than growth hormone (GH) insufficiency, the late endocrinopathies after survival from non-central brain tumours have been little documented. The aim of this study was to investigate the hypothalamic-pituitary-adrenal (HPA) axis in long-term survivors of cranial irradiation for childhood posterior fossa tumours. PROCEDURE: We studied long-term data in patients treated prepubertally for posterior fossa brain tumours and systematically referred by radiation oncologists for growth and pubertal monitoring to the London Centre for Paediatric Endocrinology over the last 25 years. They must have undergone HPA axis assessment twice, first prepubertally at documentation of growth failure, and second at completion of growth and puberty. Data on sixteen patients (12 males, 4 females; median age: 5.7 years, range: 2.5-8.8 years), who had undergone excision surgery with high dose cranial irradiation and/or chemotherapy for childhood posterior fossa tumours, were examined. Patients were followed for a median of 11.0 (range: 6.8-21.4) years after radiotherapy. HPA axis assessment was undertaken with the insulin-induced hypoglycaemia test (ITT). Basal thyroid, cortisol and gonadal function tests were undertaken annually throughout the follow-up period and any deficits replaced. RESULTS: At each ITT, all patients mounted an inadequate GH response. By the end of the follow-up period all patients remained severely GH deficient, two (12.5%) had partial ACTH insufficiency, one (6.3%) had secondary hypothyroidism but none were gonadotropin deficient or hyperprolactinaemic. CONCLUSIONS: Unlike the severe, evolving multiple pituitary deficits after treatment of pituitary or central tumours in adults, these findings in children with posterior fossa tumours suggest that, with the exception of GH, neurotoxicity due to irradiation per se is associated with a low prevalence of anterior pituitary hormone deficiencies, even at a long follow-up. Since the children in this study were selected for assessment on the basis of growth failure, the high prevalence of GH insufficiency at first testing is to be expected; however, the early onset (within 1-3 years of irradiation) and permanence we have identified supports the view that GH is the most sensitive hormone to radiation injury.     

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 pituitary stalk, (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.     

Magnetic resonance imaging in the diagnosis of growth hormone deficiency.

Forty-six patients with idiopathic growth hormone deficiency were examined by magnetic resonance imaging at a mean (+/- SEM) age of 9 +/- 1 years (range 15 days to 20 years). They were classified into two groups according to MRI images: group 1 (n = 29) had pituitary stalk interruption syndrome and group 2 (n = 17) had normal pituitary anatomy. All patients with pituitary stalk interruption had a pituitary height at less than -2 SD for age; three had no visible anterior pituitary lobe. By contrast, the pituitary height was less than normal in only 10 patients (60%) with normal pituitary anatomy. Growth hormone deficiency was transient in one of the seven patients with normal pituitary anatomy and height. The group with pituitary stalk interruption had the first symptom of growth hormone deficiency at an earlier age (2.8 +/- 0.6 vs 5.5 +/- 1.2 years; p less than 0.001), were of smaller stature (-4 +/- 0.2 vs -3 +/- 0.2 SD; p less than 0.01) and had lower GH peak response to provocative testing (3 +/- 0.4 vs 5 +/- 0.5 ng/ml; p less than 0.001) than did the group with normal pituitary anatomy. Their pituitary gland was also shorter (2.5 +/- 0.2 vs 3.5 +/- 0.2 mm; p less than 0.01). All the patients with multiple pituitary deficiencies except one (n = 19) belonged to this group. One girl with pituitary stalk interruption and deficiencies in growth hormone and thyroid-stimulating hormone had advanced central precocious puberty. We conclude that the evaluation of the shape and height of the pituitary gland by MRI is an additional tool for the diagnosis of growth hormone deficiency. The presence of pituitary stalk interruption confirms this diagnosis and is predictive of multiple anterior pituitary deficiencies. The lack of a significant increase in perinatal abnormalities in this group and the association of pituitary stalk interruption with microphallus and with facial or sella abnormalities suggest that this appearance may have an early antenatal origin. The finding of a familial case of pituitary stalk interruption suggests a genetic origin.     

Endocrinopathies associated with midline cerebral and cranial malformations

We systematically reviewed a series of patients (n = 85) with midline cerebral and cranial malformations to correlate the endocrinopathy with the neuroanatomic defect. Midline cleft lip and palate was associated not only with growth hormone deficiency (GHD) but also with diabetes insipidus (DI); holoprosencephaly and optic nerve hypoplasia with absence of the septum pellucidum had a similar incidence of GHD and DI. Optic nerve hypoplasia with absence of the septum pellucidum had the highest incidence of multiple pituitary endocrinopathies and of neonatal hypoglycaemia. Unilateral, although more commonly bilateral, optic nerve hypoplasia was associated with GHD.     

Endocrine function and morphological findings in patients with disorders of the hypothalamo-pituitary area: a study with magnetic resonance.

Evaluation of the sellar area was performed with magnetic resonance imaging in 101 patients (age range 0.8-27 years) with hypopituitarism, isolated diabetes insipidus, hypogonadotrophic hypogonadism, and central precocious puberty. The hypopituitary patients (n = 70) included multiple pituitary deficiency (n = 23), pituitary deficiency with diabetes insipidus (n = 5), and isolated growth hormone deficiency (n = 42). The patients with multiple pituitary deficiency showed pathological morphological findings in all cases, with stalk and posterior lobe always involved. The group with associated diabetes insipidus had abnormal stalk in four of five cases and posterior lobe not visible in all cases. Only five of 42 (12%) patients with isolated growth hormone deficiency had abnormalities of the sellar area. In two out of four patients with isolated diabetes insipidus posterior lobe was not seen. All patients with hypogonadotrophic hypogonadism (three with Kallmann''s syndrome, one Prader-Willi syndrome, and two idiopathic hypogonadism) appeared normal. In precocious puberty (n = 21) the three patients with onset of symptoms before age 2 years exhibited a hypothalamic hamartoma, whereas in the others with onset of puberty between age 2 and 7 the magnetic resonance image was normal in 17 of 18 patients. The probability of finding a pathological magnetic resonance image was considerably high in our patients with multiple pituitary deficiency, isolated diabetes insipidus, and precocious puberty with very early onset of symptoms. On the contrary, purely functional abnormality is suggested in most patients with isolated growth hormone deficiency, hypogonadotrophic hypogonadism, and precocious puberty with later onset of symptoms.     

High proportion of pituitary abnormalities and other congenital defects in children with congenital nasal pyriform aperture stenosis

We aimed to determine the occurrence of pituitary dysfunction and additional malformations in patients with congenital nasal pyriform aperture stenosis (CNPAS) and to predict which patients are at risk of pituitary dysfunction. Among the 40 studied patients, hypothalamo-pituitary (HP) axis abnormalities were found in 16 patients (40%), with endocrine dysfunction (n = 9) and/or abnormal HP MRI findings (n = 15). A normal HP axis on MRI was highly predictive of normal endocrine function. Of the 40 patients, 31 had additional abnormalities in the cranio-facial area (n = 26), the brain (n = 12), the vertebrae (n = 5), the limbs (n = 4), the heart (n = 7) and the kidney (n = 3). Six patients had syndromic associations: VACTERL (n = 4), CHARGE (n = 1) and RHYNS (n = 1) syndromes. Craniofacial and brain malformations were more common in patients with HP axis abnormalities than in patients with normal HP axis. Familial history of midline defects and/or consanguinity were found in 30% of patients. In conclusion, HP axis abnormalities are frequent in patients with CNPAS and justify MRI of the brain early in life and clinical evaluation to screen for patients with pituitary insufficiency. CNPAS may be a genetically heterogeneous condition with a large phenotypic variability that shares common etiological mechanisms with the various forms of the holoprosencephaly phenotype.     

Hypothalamic-pituitary dwarfism: Comparison between MR imaging and CT findings

Magnetic Resonance (MR) imaging was carried out on 33 patients with idiopathic growth hormone deficiency, in 22 of whom CT scan had been carried-out previously. Twenty-one patients presented some complications at birth. Both MR and CT were positive in the evaluation of the sella. MR imaging exhibited a higher degree of accuracy than CT in the evaluation of pituitary gland, pituitary stalk and brain anomalies.On the basis of pituitary morphology demonstrated by MR imaging, and perinatal histories, a classification is proposed which divides our patients into three group: A) a first group of 13 patients presenting severe hypoplasia of the anterior pituitary lobe, hypoplasia of the stalk and ectopia of posterior lobe. The underlying cause of these anatomic defects might be developmental in origin, and date from early intrauterine life, probably worsened at birth. B) a second group of 10 patients presenting severe hypoplasia of the anterior pituitary lobe. A perinatal event and birth trauma might be responsible for pituitary damage. C) a third group of 10 patients with no morphological abnormalities of the pituitary gland. A derangement of the neuroendocrine mechanism which control the growth hormone secretion might account for these patients.Presented at the ESPR meeting in Dublin 1989. Selected for publication by an International Group of the ESPR     

Midline brain lesions in children with hormone insufficiency indicate early prenatal damage

The relationships between midline brain morphology, anterior visual pathway morphology and hormonal status in children with impaired growth were studied. Intracranial morphology was studied by magnetic resonance imaging in 47 children (14F, 33M), median age 9.7y (range 2.6–18.7y) undergoing growth hormone treatment (GH; 0.1 U/kg/d). They were chosen to represent various birth sizes and a spectrum of hormone insufficiencies. There was a relationship between GH secretion and the morphology of the neurohypophysis, the pituitary stalk and the anterior visual pathways, i.e. the greater the GH insufficiency, the more abnormal were these structures. The children with anterior visual pathway abnormalities had the lowest GH levels and the smallest adenohypophysis. The association between abnormalities of the anterior visual pathways and the hypothalamo-pituitary structures may reflect a common prenatal neural damage in embryologically and anatomically closely related structures.     

Congenital optic nerve hypoplasia with hypothalamic-pituitary dysplasia. A review of 16 cases

Sixteen children had congenital optic nerve hypoplasia and hypothalamic-pituitary dysplasia. Investigation disclosed an extremely variable spectrum of neuroendocrinological findings that ranged from deficiency to hypersecretion of trophic hormone. Neuroendocrine abnormalities consisted mainly of trophic hormone deficiencies, the most common being growth hormone deficiency, but trophic hormone hypersecretion, including growth hormone, corticotropin, and prolactin was found as well. The extent of anterior pituitary hormone deficiency was variable. Anti-diuretic hormone deficiency was presented in two patients. Our findings support the concept of hypothalamic defect as the major cause for the pituitary dysfunction in this syndrome. Physicians should be aware of this syndrome as a common cause for growth failure and multiple pituitary hormone deficiencies in visually impaired children, which would facilitate the diagnosis and early institution of therapy for this treatable but potentially serious entity.     

MRI findings and genotype analysis in patients with childhood onset growth hormone deficiency--correlation with severity of hypopituitarism

AIM: To evaluate the relationship between pituitary size, PIT1 and PROP1 genotype, and the severity of childhood onset growth hormone deficiency (coGHD). PATIENTS: Forty-four patients with coGHD (34 M; 9.7 +/- 4.1 years): severe isolated (SI) GHD (n = 14); partial isolated (PI) GHD (n=13); multiple pituitary hormone deficiencies (MPHD) (n=17). RESULTS: Pituitary abnormalities were found in 7/14 patients with SIGHD (50%), 16/17 patients with MPHD (94.1%), and no patient with PIGHD. Mean pituitary height (PHT SDS) was significantly lower in MPHD than in SIGHD and PIGHD. Pituitary height SDS and pituitary volume (PV) SDS correlated with IGF-I SDS and stimulated GH peaks in the SIGHD and MPHD groups. No PIT1 mutation was identified. The PROP1 AG deletion (301-302) was present in five related patients with MPHD and more severe phenotype than the other patients with MPHD. CONCLUSIONS: Pituitary abnormalities corresponded to the severity of coGHD. Genetic alterations were identified in five related patients with MPHD.     

Growth hormone deficiency associated with 22q11.2 deletion: a case report

The 22q11.2 microdeletion produces many syndromes, characterized by similar phenotypical features. The most known syndromes are: the DiGeorge syndrome, the velocardiofacial syndrome, the conotruncal anomaly face syndrome. The hallmark features are represented by cardiac anomalies, palate defects, immune and cognitive deficiencies, facial dysmorphisms. Less common disorders include: genito-urinary abnormalities, visual defects, autoimmune disorders and pituitary anomalies, being the last represented by growth hormone and/or insulin growth factor-I deficiency. We present the case of a 8 years old male admitted to our Division for failure to thrive. We found growth hormone deficiency and pituitary hypoplasia associated with some of the anomalies shown above, thus we suspected and confirmed the 22q11.2 deletion syndrome. In literature few cases of associated 22q11.2 deletion syndrome with growth hormone deficiency are described, while short stature between children with and children without cleft palate is reported to be more frequent in the first ones, suggesting that the 22q11.2 deletion syndrome remains undetected in many affected children and that the growth hormone deficiency prevalence in affected children has to be investigated. The wide phenotypical presentation of 22q11.2 deletion syndrome requires a multidisciplinary approach to the affected subject and, from the auxologic point of view, is good to monitoring the growing trend and, if short stature is present, check for the growth hormone deficiency.     

Traumatic brain injury is a rarely reported cause of growth hormone deficiency

We determined the frequency of traumatic brain injury (TBI)-related growth hormone deficiency (GHD) from a large registry of growth hormone-deficient subjects and compared these subjects' clinical characteristics with those of children with idiopathic growth hormone deficiency (IGHD). A surprisingly small number of subjects with TBI-induced GHD (n = 141) were registered compared with those with IGHD (n = 23,722). At onset of treatment, the subjects with TBI-induced GHD were older (P = .045), had lower height velocity (P < .001), had a greater number of other pituitary hormone deficiencies (P < .001) and, after a year of recombinant human GH treatment, demonstrated a greater change in height velocity (P = .016). We speculate that TBI-induced GHD may be a neglected phenomenon in childhood, and recommend prospective longitudinal studies to explore its natural history and frequency.     

Russell-Silver syndrome and hypopituitarism. Patient report and literature review

Russell-Silver syndrome (RSS) is a sporadic form of prenatal onset dwarfism with typical facial features, variable asymmetry, and linear growth 3 to 4 SDs below the mean. Endocrinologic studies are usually normal; however, six cases of RSS with growth hormone deficiency have been reported, three of which had additional pituitary abnormalities. We describe another case, a 7-year-old girl with RSS and deficiencies of growth hormone, corticotropin, and thyroid-stimulating hormone. Replacement therapy including growth hormone resulted in an improved growth velocity, though twice the usual dose of growth hormone was required and short stature persisted. Since growth hormone secretion is usually normal in RSS, the existence of individuals with RSS phenotype and hypopituitarism including growth hormone deficiency suggests etiologic heterogeneity. We recommend that those individuals with RSS phenotype and a continuous significant decline in height velocity be investigated for pituitary abnormalities. Unusually high replacement doses of growth hormone may be required to overcome deficiency.     

GONADOTROPIN RESPONSIVENESS TO LUTEINIZING HORMONE RELEASING HORMONE IN PREPUBERTAL AND PUBERTAL PATIENTS WITH GROWTH HORMONE DEFICIENCY

ABSTRACT. Gonadotropin response to 100 μg/m² LHRH was determined in 31 patients with growth hormone deficiency. According to their bone ages the patients were divided into a "prepubertal" ( n =18) and a "pubertal" ( n =13) group. The results were compared with the LHRH tests from 16 healthy prepubertal boys and girls and 32 healthy adult probands, respectively. The maximum increment of LH and FSH was evaluated. In the "prepubertal" group five patients had an insufficient rise of LH and FSH, four of them having additional anterior pituitary hormone deficiencies. In the "pubertal" group nine patients were found to be gonadotropin deficient, all of them had additional hormone deficiencies, TSH being the most frequently affected hormone. Only one of 14 gonadotropin-deficient patients had no other than growth hormone deficiency in addition. An isolated decreased FSH increment without LH deficiency was found in 6 male and 2 female patients and is not thought to be of diagnostic value. No influence of growth hormone treatment or growth velocity on the gonadotropin responsiveness was found. Patients with an additional thyreotropic defect could be classified as pituitary or hypothalamic disorder due to their reaction in the TRH test. These groups could not be differentiated by a single bolus LHRH test, indicating the need of prolonged stimulation to recover the pituitary hyporesponsiveness. Due to methodological problems the diagnosis of gonadotropin deficiency in an individual patient of the prepubertal age group might be questioned. However, a normal gonadotropin response to LHRH can be expected in prepubertal patients with growth hormone deficiency and may indicate a normal gonadotropin function.