Prueba de supresión con Dexametasona 1mg en una población de individuos con normopeso, sobrepeso y obesidad: Estudio multicéntrico

the overnight oral dexamethasone test assesses the normal negative feedback of cortisol on the hypothalamic-pituitary-adrenal axis (h-p-a) 1. it is widely used in the screening of cushing？s syndrome (cs) 3,4,5. but the cut-off values for the normal response remains controversial: originally it was considered as 5 ug/dl and in the last years it was reported as 1.8 ug/dl 4. likewise, there is no agreement about the suppression values in obesity, where a hyperactivity of the h-p-a axis has been reported. therefore, the adrenal department of the argentine society of endocrinology and metabolism (saem) studied 80 healthy subjects recruited from ten hospitals of buenos aires in order to assess the normal response in our population. sixteen women and twenty men, aged 15-66 years old (x = 39.2ys), were classified into three groups, according to their body mass index (bmi): normal weight, bmi- 19-24.9 kg/m2 (n= 39); overweight, bmi- 25-29.9 kg/m2 (n=21) and obese subjects, bmi> 30 kg/m2 (n=20). they had to be euthyroid and free of corticosteroid treatment, contraceptive pills, hormone replacement therapy, rifampicin and psychotropic drugs at the time of the study. subjects referring drug abuse, alcoholism, depression, cardiovascular, and renal disorders and,obviously, adrenal diseases were excluded from the study. dexamethasone 1mg per os was administered at 11p.m. and blood was withdrawn at 8 a.m. on the next morning to determine plasma cortisol concentration. determinations were centralized in one laboratory and the ria-dsl (diagnostic system laboratories-radioimmunoassay) was used. additionally, in ten subjects plasma cortisol was also determined in the same blood samples by another radioimmunoassay kit, ria-dpc (diagnostic products corporation). the kruskall-dunn test was used to compare the plasma cortisol levels post-1mg dexamethasone among the three groups studied. in the 10 patients whose determinations were made in the same blood samples by two different ria-kits (d