A prospective analysis of the metyrapone short test using targeted and untargeted metabolomics

IntroductionThe present study aimed to prove the metyrapone short test in a day clinic to be suitable for examining the integrity of the hypothalamic-pituitary-adrenal (HPA) axis in patients with suspected secondary and tertiary adrenal insufficiency and to identify novel effector molecules in acute stress response. Methods44 patients were prospectively enrolled. Based on stimulated 11-deoxycortisol levels, patients were divided into a physiological (11-deoxycortisol >= 70 mu g/l) and a pathological (11-deoxycortisol <70 mu g/l) response group. Clinical follow-up examination was performed for validation. Ultra-performance-liquid-chromatography-tandem-mass-spectrometry and a Fourier-transform-ion-cyclotron-resonance-mass-spectrometry were used for targeted and untargeted steroid metabolomics. ResultsAt baseline, lower levels of cortisone (42 vs. 50 nmol/l, p=0.048) and 17-OH-progesterone (0.6 vs. 1.2 nmol/l, p=0.041) were noted in the pathological response group. After metyrapone administration, the pathological response group exhibited significantly lower 11-deoxycortisol (39.0 vs. 94.2 mu g/l, p<0.001) and ACTH (49 vs. 113 pg/ml, p<0.001) concentrations as well as altered upstream metabolites. Untargeted metabolomics identified a total of 76 metabolites to be significantly up- or downregulated by metyrapone. A significant increase of the bile acid glycochenodeoxycholic acid (GCDC, p<0.01) was detected in both groups with an even stronger increase in the physiological response group. After a mean follow-up of 17.2 months, an 11-deoxycortisol cut-off of 70 mu g/l showed a high diagnostic performance (sensitivity 100%, specificity 96%). ConclusionThe metyrapone short test is safe and feasible in a day clinic setting. The alterations of the bile acid GCDC indicate that the liver might be involved in the acute stress response of the HPA axis.