Background: Diagnosis of Congenital Adrenal Hyperplasia (CAH) is based on the quantification of 17-hydroxyprogesterone (17-OHP), usually by immunoassay. During the neonatal period the specificity of screening for CAH by blood spot 17-OHP immunoassay is low. High false-positive rates result in a relatively high demand for a second-tier serum confirmation test. A robust, specific and selective method for measurement of cortisol, 21-deoxycortisol, 11-deoxycortisol, 4-androstene-3,17-dione (A4) and 17-OHP in serum has been developed. The method involves a simple extraction procedure and a fast analysis using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC/MS/MS).
Methods: The steroids were extracted from 50microl of serum using methyl-tert-butyl-ether. Analysis was performed on a UPLC tandem quadrupole mass spectrometer system in positive mode electrospray ionization and multiple reaction monitoring acquisition.
Results: The assay was linear over each analyte concentration range with all correlation coefficients (r(2))>0.996. Inter- and intra-day CVs were <or=10% across the analytical range. In addition simultaneous measurement of the full range of steroids on the pathway to cortisol allows confirmation of the affected steroidogenic enzyme.
Conclusions: A second-tier test for the confirmation of CAH has been developed. The method allows for detection and quantification of 5 steroids related to CAH over the range of the clinical assay with good linearity, sensitivity and precision.
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