The consideration of external steroid therapy history and skin bruising sign with morning serum cortisol measurement predicts better results of rapid ACTH stimulation test than morning serum cortisol only
Sun Ok Song, Se Hwa Kim & Hyeong Jin Kim
The morning serum cortisol measurement has long been used as an index of adrenal function in the unstressed patient, but does not necessarily differentiate normal subjects from those with adrenal dysfunction. We investigate causes and clinical findings of adrenocortical insufficiency in this study, and will propose a model predicting results of rapid ACTH stimulation test. A consecutive series of 363 subjects who were examined rapid ACTH stimulation were recruited. Adrenocortical insufficiency was diagnosed in 103 of 363 subjects. After adjusting sex and age, morning serum cortisol level (P<0.0001), external steroid therapy history (P=0.046), and skin bruising (P=0.01) were independent factors predicting adrenocortical insufficiency by rapid ACTH stimulation test in biliniary logistic regression analysis. When morning serum cortisol level were <3, 4, and 5 μg/dl, probabilities of adrenocortical insufficiency were 83.3, 76.4, and 70.8%. When morning serum cortisol level of subjects with external steroid therapy history and skin bruising was <5 μg/dl, probability of adrenocortical insufficiency was 100%. When morning serum cortisol level of subjects without external steroid therapy history or skin bruising were more than 10, 11, 14, and 19 μg/dl, probabilities of adrenocortical insufficiency were 91.4, 92.7, 95.4, and 92.9%. When morning serum cortisol level is used to predict the result of rapid ACTH stimulation test, it rases predictive power to take together external steroid therapy history and the presence of skin bruising into consideration.