Horm Res
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Improvement of MRI diagnostic accuracy in the study of the hypothalamic-pituitary region provides precise anatomic details. In pituitary dwarfism, MRI reveals severe sella/pituitary gland and stalk hypoplasia with or without posterior pituitary ectopia, and empty sella, and this more frequently in patients with multiple pituitary hormone deficiency. Two main hypotheses have been proposed to explain these findings: traumatic stalk transection during breech delivery, and abnormal embryonic development of the pituitary gland. ⋯ In diabetes insipidus, MRI findings are normal picture, posterior lobe not visible, and thickened stalk (as expression of preclinical/initial histocytosis). Patients with central precocious puberty or hypogonadotropic hypogonadism rarely show morphologic abnormalities (hamartoma of the tuber cinereum, partially empty sella). So far, MRI permits one to identify morphologic pictures in diseases previously considered 'idiopathic'.
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Communication between the central components of the stress response and the immune system plays an important role in susceptibility to inflammatory disease. This communication occurs through hormonal and neuronal mechanisms. Hormonal mechanisms involve activation of the hypothalamic-pituitary-adrenal (HPA) axis by immune system products, e.g. cytokines. ⋯ Cytokine activation of the HPA axis and the resultant glucocorticoid-induced suppression of immune and inflammatory responses represent an important mechanism whereby the central stress response modulates peripheral inflammation. Interruption of this communication is associated with exacerbation of inflammatory disease. Conversely, intracerebroventricular transplantation of hypothalamic tissue from inflammatory resistant rats into susceptible rats reduces peripheral inflammation by more than 85%.
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Case Reports
Kinetics of the pituitary-thyroid axis and the peripheral thyroid hormones in 2 children with thyroxine intoxication.
Thyroxine intoxication is a benign, nonfatal condition, relatively common in the pediatric age group. We present here a detailed laboratory follow-up of all thyroidal hormones in 2 healthy girls who inadvertently ingested 2,500 micrograms of L-thyroxine. The two girls were hospitalized and treated with ipecac, gastric lavage, propranolol, prednisone, cholestyramin and propyl-thiouracil. ⋯ The T3/rT3 ratio decreased from a normal level of around 3 to as low as 1 and rose again after 13 days to extremely high levels (as high as 8). Tg serum levels dropped continuously with a half-life of 1-5 days and started rising again after 2-13 days. In conclusion, T4 intoxication in the child is combated primarily by a significant increase in T3 production and degradation, while meticulously maintaining relatively low T3 levels.