Department of Laboratory Medicine and Pathology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA. Congenital adrenal hyperplasia (CAH) is primarily caused by 21-hydroxylase deficiency and leads to an accumulation of 17-hydroxyprogesterone and reduced cortisol levels. Newborn screening for CAH is traditionally based on measuring 17-hydroxyprogesterone by different immunoassays. Despite attempts to adjust cutoff levels for birth weight, gestational age, and stress factors, the positive predictive value for CAH screening remains less than 1%. To improve this situation, we developed a method using liquid chromatography-tandem mass spectrometry to measure 17-hydroxyprogesterone, androstenedione, and cortisol simultaneously in blood spots. A total of 1222 leftover blood spots from six different screening programs using different immunoassays (fluorescent immunoassay and ELISA) were reanalyzed in a blinded fashion by liquid chromatography-tandem mass spectrometry. Thirty-one samples were from babies with CAH, 190 had yielded false-positive results by immunoassay, and the remaining 1001 samples were from babies with normal screening results. Steroid profiling allowed for an elimination of 169 (89%) of the false-positive results and for an improvement of the positive predictive value from the reported 0.5 to 4.7%.Although this method is not suitable for mass screening due to the length of the analysis (12 min), it can be used as a second-tier test of blood spots with positive results for CAH by the conventional methods. This would prevent unnecessary blood draws, medical evaluations, and stress to families. PMID: 15292289 [PubMed - indexed for MEDLINE]

Department of Paediatrics, Leiden University Medical Center, Leiden, The Netherlands. H.J.van_der_Kamp@LUMC.nl Congenital adrenal hyperplasia (CAH) is well suited for newborn screening, as it is a common and potentially fatal disease which can be easily diagnosed by a simple hormonal measurement in blood. Moreover, early recognition and treatment can prevent severe salt wasting, dehydration and death and shorten the time of male sex assignment in virilised females.In screening programmes, 17alpha-hydroxyprogesterone (17OHP) is measured in filter paper blood spots obtained by a heel puncture preferably between 2 and 4 days after birth. Three assay techniques are utilised for initial screening: radio-immunoassay (USA), enzyme-linked immunosorbent assay (Japan) and time-resolved fluoro-immunoassay (Europe). Preterm newborns have higher 17OHP concentrations in serum than babies born at term. Therefore, cut-off levels are based on gestational age (in Japan and Europe) or on birth weight (in the USA). There is a considerable variation in cut-off levels from one programme to another. This is most likely due to the different antibodies and reagents used, varying thickness and density of filter paper used for sample collection and, most significantly, the characteristics of the reference population (in terms of birth weight and gestational age).More than 30 million newborns have been screened. The prevalence of CAH in the USA and Europe is approximately 1:15 000-16 000, and slightly lower in Japan (1:19 000). In general, severe salt wasting can be prevented, but there is a remarkable variation in the number of false-positives and false-negatives among the various programmes. Ongoing refinement of cut-off levels is needed to improve specificity and sensitivity. PMID: 15554889 [PubMed - indexed for MEDLINE]