2,243 publications from this institution
No abstract is provided for this article.
No abstract is provided for this article.
First Department of Pediatrics, University of Athens, Athens, Greece (Chrousos) Department of Pathophysiology, University of Athens, Athens, Greece (Kaltsas)
The stress response is subserved by the stress system, which is located both in the central nervous system and the periphery. The principal effectors of the stress system include corticotropin-releasing hormone (CRH); arginine vasopressin; the proopiomelanocortin-derived peptides alpha-melanocyte-stimulating hormone and beta-endorphin, the glucocorticoids; and the catecholamines norepinephrine and epinephrine. Appropriate responsiveness of the stress system to stressors is a crucial prerequisite for a sense of well-being, adequate performance of tasks, and positive social interactions. By contrast, inappropriate responsiveness of the stress system may impair growth and development and may account for a number of endocrine, metabolic, autoimmune, and psychiatric disorders. The development and severity of these conditions primarily depend on the genetic vulnerability of the individual, the exposure to adverse environmental factors, and the timing of the stressful events, given that prenatal life, infancy, childhood, and adolescence are critical periods characterized by increased vulnerability to stressors.
The dexamethasone-suppressed CRH test (Dex-CRH test) differentiates patients with Cushing’s syndrome (CS) from those with pseudo-Cushing states, who have decreased ACTH responses to CRH because of negative feedback exerted by chronic hypercortisolism. Normal subjects, however, have not been studied with the Dex-CRH test, raising concern that this test might not separate patients with CS from patients with normal adrenal function. To determine whether the criterion that separates CS from pseudo-Cushing states also would differentiate patients with Cushing’s disease (CD) from individuals with eucortisolism, we studied 20 healthy volunteers during low-dose (2 mg/day) dexamethasone suppression, and then during the Dex-CRH test (CRH stimulation test performed 2 h after completion of low-dose dexamethasone suppression), and contrasted their results with those of 20 patients with surgically proven mild CD [urine free cortisol (UFC) <1000 nmol/day). Basal UFC was significantly greater in patients with CD (P < 0.001) but within the normal range (55–250 nmol/day) in 4 patients. During low-dose dexamethasone suppression, a UFC less than 100 nmol/day (36 μg/day) was found in all but 1 volunteer subject, and a urine 17-hydroxycorticosteroid excretion less than 14.6 μmol/day (5.3 mg/day) was found in all but 2 subjects. During the Dex-CRH test, plasma cortisol less than 38 nmol/L was found in all 20 normal volunteers until 30 min after CRH administration. By contrast, the 15-min CRH-stimulated plasma cortisol exceeded 38 nmol/L in all patients with CD (P < 0.001). Plasma dexamethasone measured just before CRH administration was similar in normal volunteers (13.0 ± 6.1 μmol/L) and patients with CD (16.4 ± 6.4 μmol/L). We conclude that cortisol measurements obtained during the Dex-CRH test are suppressed in normal volunteers below those found in mild CD. These results suggest that the Dex-CRH test may be useful in the evaluation of CS in patients without significant hypercortisoluria. However, its value in patients with episodic hormonogenesis has not been tested.