Anna Elsa Maria Allegri

Diabetes insipidus--diagnosis and management.

Central diabetes insipidus (CDI) is the end result of a number of conditions that affect the hypothalamic-neurohypophyseal system. The known causes include germinoma/craniopharyngioma, Langerhans cell histiocytosis (LCH), local inflammatory, autoimmune or vascular diseases, trauma resulting from surgery or an accident, sarcoidosis, metastases and midline cerebral and cranial malformations. In rare cases, the underlying cause can be genetic defects in vasopressin synthesis that are inherited as autosomal dominant, autosomal recessive or X-linked recessive traits. The diagnosis of the underlying condition is challenging and raises several concerns for patients and parents as it requires long-term follow-up. Proper etiological diagnosis can be achieved via a series of steps that start with clinical observations and then progress to more sophisticated tools. Specifically, MRI identification of pituitary hyperintensity in the posterior part of the sella, now considered a clear marker of neurohypophyseal functional integrity, together with the careful analysis of pituitary stalk shape and size, have provided the most striking findings contributing to the diagnosis and understanding of some forms of ‘idiopathic’ CDI. MRI STIR (short-inversion-time inversion recovery sequencing) is a promising technology for the early identification of LCH-dependent CDI.

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.

Central Diabetes Insipidus in Children and Young Adults: Etiological Diagnosis and Long-Term Outcome of Idiopathic Cases

CONTEXTnCentral diabetes insipidus (CDI) is considered idiopathic in 20% to 50% of affected subjects.nnnOBJECTIVEnThe purpose of this study was to determine whether a systematic diagnostic workup could achieve better etiologic diagnosis in children and adolescents presenting with polyuria and polydipsia.nnnDESIGN AND SETTINGnThis is a prospective study conducted at a tertiary referral center. Patients underwent clinical and endocrine evaluations every 6 months and neuroimaging every 6 months for 2 years and yearly for 3 years. Endocrine function and neuroimaging were also reassessed after adult height achievement.nnnPARTICIPANTSnA total of 85 consecutive patients with CDI were enrolled at a median age of 7.5 years; those with idiopathic CDI were stratified based on pituitary stalk thickness.nnnMAIN OUTCOME MEASURESnTo establish the etiology of CDI, we determined the time lag between its onset and the specific diagnosis, the long-term impact on pituitary function, and the overall long-term outcomes.nnnRESULTSnOf the subjects, 24 (28.2%) received an etiologic diagnosis at presentation and 11 (13%) within 2.5 years (n = 7 germinomas and n = 4 Langerhans cell histiocytosis), 7 (8.2%) were lost to follow-up, and 43 (50.6%) were considered to have idiopathic disease and were followed until the median age of 17.3 years. Neuroimaging identified 40 of 43 patients with self-limited inflammatory/autoimmune pituitary stalk thickness within the first 6 months, the severity of which was significantly correlated to pituitary dysfunction. The probability of >10-year-survival without an anterior pituitary defect was related to the severity of pituitary stalk thickness, and 53% showed permanent anterior pituitary defects. Three patients developed Langerhans cell histiocytosis and 1 developed Hodgkin lymphoma after a median of 9 and 13 years, respectively.nnnCONCLUSIONSnA diagnostic etiology was achieved in 96% of patients with CDI. Risk stratification based on the degree of pituitary stalk thickness is of prognostic value for long-term outcomes including permanent pituitary dysfunction. New guidance is provided for the management of these patients.

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

CONTEXTnThe accuracy of the glucagon test in the diagnosis of central adrenal insufficiency in young children has not yet been definitively established.nnnOBJECTIVEnThe 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.nnnDESIGN AND SETTINGnThis was a prospective study conducted in two Pediatric Endocrinology Centers.nnnPATIENTS AND METHODSnForty-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.nnnRESULTSnThe 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.nnnCONCLUSIONSnThis study shows that glucagon is an accurate and safe diagnostic test for adrenal function in young children who are at risk for adrenal insufficiency.

Posterior pituitary (PP) evaluation in patients with anterior pituitary defect associated with ectopic PP and septo-optic dysplasia

OBJECTIVEnControversies exist about posterior pituitary (PP) function in subjects with ectopic PP (EPP) and with cerebral midline defects and/or their co-occurrence. We investigate water and electrolyte disturbances in patients at risk for PP dysfunction.nnnDESIGNnThe study was conducted in a single Pediatric Endocrinology Research Unit.nnnMETHODSnForty-two subjects with childhood-onset GH deficiency were subdivided into five groups: normal magnetic resonance imaging (n=8, group 1); EPP (n=15, group 2); septo-optic dysplasia (SOD) with normal PP (n=4, group 3); EPP and SOD without (n=7, group 4), and with additional midline brain abnormalities (n=8, group 5). At a mean age of 16.0±1.1 years, they underwent a 120u200amin i.v. infusion with hypertonic 5% saline and evaluation of plasma osmolality (Posm), arginine vasopressin (AVP), thirst score (in groups 1 and 2), and urinary osmolality were performed.nnnRESULTSnMean Posm and AVP significantly increased from baseline scores (284.7±4.9u200amosm/kg and 0.6±0.2u200apmol/l) to 120u200amin after saline infusion (300.5±8.0u200amosm/kg and 10.3±3.3u200apmol/l, P<0.0001). Group 5 showed higher mean Posm and lower mean AVP at all time points (P<0.0001). Mean thirst score did not show a significantly different trend between the groups 1 and 2. Urine osmolality was above 750u200amosm/kg in all but seven patients after osmotic challenge.nnnCONCLUSIONSnPatients with midline brain abnormalities and EPP have defective osmoregulated AVP. Patients with EPP and congenital hypopituitarism have normal PP function.

Age- and sex-matched reference curves for serum collagen type I C-telopeptides and bone alkaline phosphatase in children and adolescents: An alternative multivariate statistical analysis approach

Abstract Introduction The availability of pediatric age- and sex-matched reference curves for bone markers is essential for appropriate assessment of bone turnover and treatment follow-up of bone disorders. The aim of this work was to obtain updated reference equations for collagen type I C-telopeptides (CTX-1) and bone alkaline phosphatase (BAP) by using an alternative statistical approach. The study included 1502 Italian pediatric subjects from 6xa0months to 16xa0years of age (686 females and 816 males) subjected to CTX-1 and BAP measurement during a six-year period. Methods The unselected population of patients was used for the calculation of age- and sex-matched reference curves by using a multivariate statistical analysis after an appropriate validation with a selected population of 184 healthy subjects (6xa0months-16xa0years; 88 females and 96 males). The effect of age, sex, puberty based on Tanner stage evaluation and anthropometrics on the variations of the two bone markers was then studied. Results Pediatric reference curves were obtained for CTX-1 and BAP from 3465 results retrieved by our Laboratory Information System. The equations for the calculation of reference values were obtained for boys and girls. The two bone markers markedly varied according to age, sex and pubertal stage with females displaying higher values during Tanner stages II and III and males during stages III and IV. Conclusions The application of a novel statistical approach provided reference curves for CTX-1 and BAP. This method, moreover, could be applied in pediatrics to obtain reference intervals for other biomarkers.