Síndrome de interrupción del tallo pituitario: Relaciones clínicas, bioquímicas y neurorradiológicas / Pituitary stalk interruption syndrome: Clinical, biochemical and neuroradiological relationships

El síndrome de interrupción del tallo pituitario (PSIS) se caracteriza por la demostración neurorradiológica de un tallo pituitario ausente, interrumpido o hipoplásico, adenohipófisis aplásica/hipoplásica o neurohipófisis ectópica. Este síndrome se ha relacionado con formas severas de hipopituitarismo congénito (HPC), asociado a múltiples deficiencias de hormonas pituitarias (MPHD). Evaluamos a pacientes con HPC y PSIS, analizando los signos y los síntomas neonatales al diagnóstico, relacionándolos con las deficiencias hormonales pituitarias y signos neurorradiológicos presentes. Estudiamos retrospectivamente a 80 pacientes asistidos en el Hospital de Niños de Córdoba, con diagnóstico de HPC, de los cuales 42 (52%) presentaron PSIS; 22 mujeres y 20 varones, EC: 5 días-9,5 años. El 62% presentó MPHD y el 38% insuficiencia somatotrófica aislada (IGHD). El análisis de las variables perinatales demostró antecedentes de parto natural en el 52% (11/21) de las MPHD vs. 13% (2/15) de las IGHD. Cuatro pacientes, 2 con MPHD y 2 con IGHD presentaban antecedentes obstétricos consistentes en presentación podálica y transversa respectivamente, todos ellos resueltos mediante operación cesárea. Los signos y los síntomas perinatales fueron hipo- glucemia: 61% en MPHD vs. 19% en IGHD, p: 0,0105; ictericia: 38% en MPHD vs. 25% en IGHD; micropene: 77% en MPHD y colestasis: 19% en MPHD. Convulsiones neonatales se presentaron en el 75% de los niños con MPHD e hipoglucemia. EC media de consulta: 2,1 años en MPHD (30% en el período neonatal, 70% antes de 2 años) y 3,6 años en IGHD (44% en menores de 2 años). Los pacientes con MPHD presentaban: tallo no visible 81% (n: 21/26) vs. tallo hipoplásico: 19% (n: 5/26), p: 0,0001; en IGHD 56% (n: 9/16) vs. 44% (n: 7/16), p: 0,5067, respectivamente. El 100% de los neonatos con HPC tenían tallo pituitario ausente. Concluimos que la demostración de PSIS en niños con HPC proporciona información valiosa como predictor de la severidad fenotípica, la presencia de MPHD y de la respuesta al tratamiento. La baja frecuencia de antecedentes obstétricos posicionales potencialmente distócicos, como parte de los mecanismos fisiopatogénicos responsables de PSIS, indicaría la necesidad de analizar la importancia de posibles factores genéticos y epigenéticos involucrados. El diagnóstico precoz de HPC debe sospecharse en presencia de signos y síntomas clínicos, tales como hipoglucemia, colestasis, micropene y defectos asociados en la línea media facial. La resonancia magnética cerebral debe formar parte de los estudios complementarios en pacientes con esta presunción diagnóstica, especialmente a edades tempranas. El reconocimiento tardío de esta entidad puede aumentar la morbilidad y la mortalidad con efectos potenciales deletéreos y permanentes.

Pituitary stalk interruption syndrome (PSIS) is characterised by the combination of an interrupted or thin pituitary stalk, absent or ectopic posterior pituitary, and anterior pituitary hypoplasia. It is manifested as isolated (IGHD) or combined pituitary hormone deficiencies (CPHD) of variable degrees and timing of onset, with a wide spectrum of clinical phenotypes. PSIS may be an isolated morphological abnormality or be part of a syndrome. A retrospective evaluation is presented of clinical signs and symptoms present at early life stages, as well as an analysis of their relationship with hormone laboratory tests and diagnostic imaging in children with congenital hypopituitarism (CHP), and PSIS. This study was performed in a single centre on a sample of 42 children out of a total of 80 CHP patients, with a chronological age range between 5 days and 9.5 years from a database analysed over a period of 26 years. The study included 26/42 (62%) with CPHD and 16/42 (38%) with IGHD. The analysis of perinatal variables showed a natural delivery in 52% (11/21) of CPHD vs 13% (2/15) of IGHD. Four patients, two with CPHD and two IGHD had breech and transverse presentation respectively. All of them were resolved by caesarean section. The perinatal histories showed hypoglycaemia (61% CPHD vs 19% IGHD, P=.0105), jaundice (38% CPHDvs25% IGHD), micropenis (75%CPHD), hypoglycaemic seizures (75% CPHD), and cholestasis (19% CPHD). The mean CA of consulting for CPHD patients was 2.1 years, 30% in neonatal period and 70% before 2 years. The mean chronical age (CA) was 3.6 years in IGHD patients, with 44% of them less than 2 years. MRI showed that 81% of CPHD patients had absence of pituitary stalk vs 19% with thin pituitary stalk (P=.0001); Patients with IGHD presented 56% absence of pituitary stalk vs 44% with thin pituitary stalk (P=.5067). All (100%) of the patients diagnosed in the neonatal stage had absent pituitary stalk. The characterisation of GH deficient patients by presence and type of hypothalamic-pituitary imaging abnormality provides valuable information as a predictor of phenotypic severity, treatment response, and the potential to develop additional hormonal deficiencies. We conclude that demonstrating PSIS in children with HPC provides valuable information as a predictor of phenotypic severity, presence of MPHD, and response to treatment. The low frequency of potentially dysfunctional positional obstetric history, as part of the pathophysiological mechanisms responsible for PSIS, would indicate the need to analyse the importance of possible genetic and epigenetic factors involved. Early diagnosis of HPC should be suspected in the presence of clinical signs and symptoms, such as hypoglycaemia, cholestasis, micropenis, and associated facial midline defects. MRI should be part of complementary studies in patients with this diagnostic suspicion, especially at an early age. Late recognition of this entity may increase morbidity and mortality with potential permanent deleterious effects.

Talla baja: Tratamiento con hormona de crecimiento humana recombinante / Short stature: Treatment with recombinant human growth hormone

La talla baja es causa de preocupación en los niños y sus padres. Asimismo, puede representar el primer signo de una enfermedad subyacente. Es importante realizar una evaluación detallada del niño con talla baja para identificar su etiología. El tratamiento de la talla baja se direcciona a la causa primaria. La terapia con hormona de crecimiento humana recombinante (rhGH) está indicada solo en determinados pacientes. Se han aprobado ocho indicaciones de rhGH en niños con talla baja: Deficiencia de hormona de crecimiento, insuficiencia renal crónica, síndrome de Turner, síndrome de Prader Willi, antecedente de recién nacido pequeño para su edad gestacional sin crecimiento compensatorio, talla baja idiopática, alteración del gen SHOX y síndrome de Noonan. La identificación precoz y tratamiento adecuado de la talla baja se asocian a mejores resultados en los pacientes.

Short stature may cause concern for children and their parents; on the other hand, represent the first sign of an underlying disease. It is important to make a detailed assessment of children with short stature to identify its etiology. Treatment of short stature is aimed at the primary etiology; therapy with recombinant human growth hormone (rhGH) is indicated in certain patients. Eight indications of rhGH in children with short stature have been approved: Growth hormone deficiency, chronic kidney disease, Turner syndrome, Prader Willi syndrome, small for gestational age with failure to catch up to the normal height percentiles, idiopathic short stature, SHOX gene haploinsufficiency and Noonan syndrome. Early identification and appropriate treatment of short stature is associated with better outcomes for patients.

Melatonina y deficiencia de hormona de crecimiento: contribucin a la evaluacin de los desrdenes neuroendocrinos / Melatonin and growth hormone deficiency: a contribution to the evaluation of neuroendocrine disorders

La melatonina constituye un integrante fundamental del denominado "reloj biolgico" y las alteraciones hormonales sueo-dependientes. Siendo la secrecin fisiolgica de GH, predominantemente nocturna, evaluamos en un grupo de nios y adultos deficitarios de GH (GHD) sin y con tratamiento sustitutivo, la secrecin nocturna de melatonina. Estudiamos 44 pacientes GHD: Grupo a (Ga): Nios sin tratamiento; Grupo b (Gb): Nios con tratamiento con GH (0.16 mg/Kg/semana, dosis estable por mnimo de 6 meses); Grupo c (Gc): Adultos sin tratamiento y Grupo d (Gd): Adultos con tratamiento con GH (0.1- 0.8 mg/da, para mantener IGF1 entre 0 y +2 SDS, dosis estable por mnimo de 6 meses). Todos los pacientes con dficits hormonales asociados estaban adecuadamente sustituidos. La produccin de melatonina fue evaluada a travs de la medicin de su principal metabolito urinario: 6-Sulfatoximelatonina (6-SM), dosado por radioinmunoensayo, en muestras nocturnas (6PM a 8AM). Los niveles de 6-SM nocturna expresados como μg/unidad de tiempo fueron (media SEM) para el grupo peditrico: Ga = 6.50 ( 5.10) y Gb = 8.21 ( 5.31) (Test de Mann-Whitney, p = 0.82). Para los adultos fueron: Gc = 2.99 ( 1.17) y Gd = 6.60 ( 2.00) (Test de Mann-Whitney, p = 0.35). En algunas alteraciones hipotlamo-hipofisarias han sido descriptas modificaciones del patrn secretorio de melatonina, pero no se han caracterizado en forma completa an, las posibles variaciones en pacientes con GHD. Si bien en las condiciones de este estudio, no hallamos diferencias en la excrecin nocturna de 6-SM entre los GHD no tratados y los tratados en ambos grupos, ello no invalida la existencia de posibles diferencias que podran detectarse estudiando la secrecin diurna de melatonina y su diferencia con la secrecin nocturna. Todo ello podr contribuir al conocimiento de los posibles desrdenes cronobiolgicos involucrados en la deficiencia de GH.

Melatonin, a hormone secreted by the pineal gland, constitutes a landmark in neuroendocrine integration. The relationship between melatonin and different pituitary hormones and sex steroids has been studied; however, the relationship between growth hormone (GH) and melatonin remains unclear. Considering that melatonin is an essential component of the so-called "biological clock", related to circadian rhythm, day-night cycle, and sleep-dependent hormonal alterations, and knowing that physiological GH secretion occurs predominantly at night, we decided to evaluate nocturnal melatonin secretion in a group of GH-deficient children and adults on and off replacement therapy. Patients and Methods: We studied 44 patients with GH deficiency (GHD), duly confirmed by pharmacological tests, divided into 4 groups: Group a (Ga ): untreated GHD children; Group b (Gb): GHD children on GH replacement therapy (0.16 mg/Kg/week, stable dose for at least 6 months); Group c (Gc): untreated GHD adults and Group d (Gd): GHD adults on GH replacement therapy (0.1- 0.8 mg/day, to maintain IGF1 between 0 and +2 SDS, stable dose for at least 6 months). All associated hormonal deficits were adequately replaced. Melatonin production was evaluated by measuring the excretion of its major urinary metabolite: 6-Sulphatoxymelatonin (6-SM). Urinary 6-SM was measured (radioimmunoassay, Stockgrand Ltd, Guildford, UK) in nocturnal samples (6PM to 8AM) in all patients. Results: Nocturnal 6-SM levels expressed as μg/unit of time were (mean SEM) for the pediatric group: Ga = 6.50 ( 5.10) and Gb = 8.21 ( 5.31) (Mann Whitney test, p = 0.82). For adults: Gc = 2.99 ( 1.17) and Gd = 6.60 ( 2.00) (Mann Whitney test, p = 0.35). Discussion and Conclusions: It is difficult to characterize the relationship between melatonin and GH in healthy individuals; however, the administration of intravenous melatonin stimulates GH secretion in normal adults. In some hypothalamic-pituitary alterations, changes in the secretory pattern of melatonin have been reported, but possible variations in GHD patients have not been thoroughly characterized yet. This led us to evaluate 6-SM concentrations in GH deficient children and adults on and off adequate replacement therapy. One of the major aspects of this study has been the evaluation of baseline 6-SM concentrations, with no physiological or pharmacological stimulation. Even if under the conditions of this study we found no differences in nocturnal excretion of 6-SM between untreated and treated GHD individuals in both groups, this does not rule out the potential existence of differences that might be detected by studying diurnal melatonin secretion and its difference with nocturnal secretion. Such studies may contribute to an understanding of potential chronobiological disorders involved in GH deficiency.

La corrección de la sustitución excesiva de cortisol mejora la morbilidad en pacientes con hipopituitarismo: un estudio piloto / Correction of Cortisol Overreplacement Ameliorates Morbidities in Patients with Hypopituitarism: A pilot study

Context: Hyporituitarism in adults is known to be associated with deleterious effects on body composition, lipid profile and quality of life (QoL). This was attributed to GH deficiency. The potential role of glucocorticoid overreplacement had never been investigated. Objective: To investigate whether reduction in glucocorticoid replacement dose to more physiological one could ameliorate the "AO-GHD"-attributed symptomatology in patients with hypopituitarism. Design: Eleven patients with panhypopituitarism taking 20-30 mg/day of hydrocortisone, but on no GH replacement were switched to 10 to 15 mg of hydrocortisone daily. Both basally and 6-12 months later, their body mass index, body composition by dual-energy x-ray absorptiometry, lipid profile, and the score of quality of life, QOL-AGHDA were measured. Results: Within 6-12 months of lower hydrocortisone dose, subjects lost an average of 7.1 kg of total body fat and 4.1 kg of abdominal fat. No changes were seen in lean body mass, bone mineral content and HOMA-IR Plasma total cholesterol and triglyceride concentrations decreased significantly (<0.05) and the QoL improved (p=0.018). Conclusions: Our pilot study suggests that decreasing the glucocorticoid replacement dose to ~ 15 mg/ day is beneficial in terms of patients' body composition, lipid profile and quality of life.

Distribución de las frecuencias alélicas y genotípicas del polimorfismo GHRd3 en pacientes venezolanos con talla baja

Objetivos. La deleción (GHRd3) o inserción (GHRfl) del exón 3 es un polimorfismo común en el gen del receptor de la hormona de crecimiento (GHR) en los seres humanos. La presencia del alelo GHRd3 se ha asociado con el grado de respuesta de terapia con Hormona de Crecimiento Recombinante Humana (rhGH). El objetivo de este estudio fue determinar las frecuencias alélicas y genotípicas de este polimorfismo en un grupo de 69 niños venezolanos con talla baja que estaban recibiendo rhGH. Métodos. Se extrajo DNA a través de la técnica del método combinado Fenol/Sevag e Inorgánica. Se determinó el genotipo del exón 3 del gen GHR usando tanto PCR- monoplex como PCR-multiplex. Resultados. Entre los pacientes con talla baja la frecuencia genotípica se distribuyó de la siguiente manera: GHRfl/GHRfl (55%) GHRfl/GHRd3 (35%) y GHRd3/GHRd3 (10%) y la frecuencia alélica fue de 0,27 para GHRd3 y 0,73 para GHRfl. Para el grupo testigo la frecuencia genotípica se distribuyo así: GHRfl/GHRfl (56%), GHRfl/ GHRd3 (30%) y GHRd3/GHRd3 (14%) y la frecuencia alélica era de 0,29 para GHRd3 y 0,71 para GHRfl. Las características clínicas basales de los pacientes con talla baja eran similares entre los diferentes genotipos encontrados en el grupo de estudio. Conclusiones. La proporción del genotipo y los alelos del gen GHR fueron similares entre el grupo testigo y los pacientes con talla baja, lo que traduce que la etiología de la talla baja no obedece a este polimorfismo.

Objective. The deletion (GHRd3) or insertion (GHRfl) of exon 3 is a common polymorphism in the receptor growth hormone gene (GHR) in humans. The presence of the allele GHRd3 has been associated with the degree of responsiveness to therapy with recombinant human Growth Hormone (rhGH). The aim of this study was to determine the genotypic and allele frequencies of this polymorphism in a group of 69 Venezuelan children with short stature who were receiving rhGH. Methods. Genomic DNA was extracted from blood lymphocytes using combined method Fenol/SEVAG + Salting out. The GHR-exon 3 was genotyped using both PCR monoplex and multiplex assays. Results. Among patients with short stature, genotype frequency was distributed as follows: GHRfl/GHRfl (55%), GHRfl/GHRd3 (35%) and GHRd3/GHRd3 (10%) and allele frequency for GHRd3 and GHRfl was 0.27 and 0.73, respectively. For the control group, genotype frequency was distributed as follows: GHRfl/GHRfl (56%), GHRfl/GHRd3 (30%) and GHRd3/GHRd3 (14%) and allele frequency for GHRd3 and GHRfl was 0.29 and 0.71, respectively. The baseline clinical features of patients with short stature were similar among different genotypes found in the study group. Conclusions. The proportion of genotype and allele of the GHR gene were similar between the control group and patients with short stature, which translates that the etiology of short stature is not due to this polymorphism.

Anormalidades metabólicas en la deficiencia de la hormona de crecimiento / Metabolic Abnormalities in growth hormone deficiency

Increased cardiovascular morbidity and mortality has been reported in adult subjects with growth hormone deficiency (GHD). Long term follow up of a large cohort of patients with adult onset GHD, suggests that GH therapy may contribute to a reduced risk of nonfatal stroke, particularly in women and in a decline in nonfatal cardiac events in GHD men(1,2). Adult hypopituitary patients with untreated growth hormone deficiency have been shown to have a cluster of cardiovascular risk factors such as increased visceral adiposity, disturbances in lipoprotein metabolism, premature atherosclerosis, impaired fibrinolytic activity, increased peripheral insulin resistance, abnormal cardiac structure, impaired cardiac performance and endothelial dysfunction (3,4). Several of these risk factors have now been confirmed in double blind, randomized, placebo controlled trials (5,6). Metabolic changes in GH deficient children and adolescents have been evaluated only quite recently and superficially. In this article we will discuss these metabolic abnormalities and their underlying mechanism in untreated GHD subjects and we will review the beneficial effect of growth hormone therapy in adults, adolescents and children with GHD.

Se ha reportado un aumento en la morbilidad y mortalidad de pacientes adultos con deficiencia de la hormona de crecimiento (DHC). El seguimiento a largo plazo de una cohorte de pacientes con DHC sugiere que la administracion de hormona de crecimiento puede contribuir a una reducción en el número de los accidentes cerebrovasculares no fatales, particularmente en mujeres y de eventos cardíacos en hombres(1,2). Pacientes adultos con hipopituitarismo y una DHC cursan con un acúmulo de factores de riesgo cardiovascular tales como un aumento en la adiposidad visceral, alteraciones en el metabolismo lipoproteico, ateroesclerosis prematura, actividad fibrinolítica alterada, resistencia a la insulina, masa y función cardíaca alterada y disfunción endotelial (3,4). Varios de estos factores de riesgo han sido comprobados en estudios doble ciego, randomizados con placebo (5,6). Las alteraciones metabólicas en niños y adolescentes deficientes de hormona de crecimiento han sido evaluadas sólo recientemente y de manera aún superficial. En este manuscrito discutiremos estas anormalidades y los mecanismos etilógicos subyacentes en sujetos DHC no tratados y revisaremos el efecto beneficioso de la terapia con hormona de crecimiento en niños, adolescentes y adultos.

Aspectos genéticos de la talla baja: Revisión

La talla baja es una condición que afecta el crecimiento lineal en el proceso de desarrollo del individuo es ocasionada por múltiples factores pero con un fuerte componente genético. En los últimos años, se ha incrementado el conocimiento de las causas genéticamente determinadas de talla baja debido a reporte de pacientes con características especiales, quienes han ofrecido una excelente oportunidad para estudiar genes que juegan un papel crucial en el crecimiento. En esta revisión se delinea, desde la perspectiva de un médico genetista, un flujograma diagnóstico a ser considerado en todo paciente con talla baja.

Short stature is a condition affecting the body growth in the development process of an individual which is caused by multiples factors, but with a strong component genetic. In the last few years, our knowledge of genetically determined causes of short stature has greatly increased by reports of challenging patients, who offered the opportunity to study genes that play a role in growth. In this review, a diagnostic flow chart is delinead to consider in all patients with short stature from the perspective of a medical geneticist.