title: Pilot proficiency testing study for second tier congenital adrenal hyperplasia newborn screening.
abstract: BACKGROUND
  Congenital adrenal hyperplasia (CAH) is caused by inherited defects in steroid biosynthesis. The Newborn Screening Quality Assurance Program (NSQAP) initiated a pilot, dried-blood spot (DBS)-based proficiency testing program designed to investigate materials and laboratory performance for second tier CAH screening by tandem mass spectrometry (MS/MS).
  
  
  METHODS
  The ratio of 17-α-hydroxyprogesterone (17-OHP), androstenedione (4-AD) and cortisol is used as an indicator of CAH in laboratory protocols for second tier analysis of DBS specimens. DBS prepared by NSQAP contained a range of steroid concentrations resulting in different clinical ratios. Laboratories received blind-coded DBS specimens and reported results to NSQAP for evaluation.
  
  
  RESULTS
  Quantitative values reported by participants for 17-OHP, 4-AD, and cortisol, reflected small differences in their analytical methods. Average quantitative values for 17-OHP increased from 81% to 107% recovery over the 3.5-year period; cortisol recoveries increased from 61.9% to 89.5%; and 4-AD recoveries decreased from 184% to 68%.
  
  
  CONCLUSIONS
  Laboratory participation in the CAH second tier proficiency testing program has resulted in improved analyte recoveries and enhanced sample preparation methodologies. NSQAP services for the second tier CAH analysis in DBS demonstrate the need for surveillance to ensure harmonization and continuous improvements, and to achieve sustained high-performance of newborn screening laboratories worldwide.
authors.affiliation: Newborn Screening Quality Assurance Program, Centers for Disease Control and Prevention, Atlanta, GA, USA. vdejesus@cdc.gov
authors.forename: Víctor R
authors.initials: VR
authors.lastname: De Jesús
authors.forename: David A
authors.initials: DA
authors.lastname: Simms
authors.forename: Jarad
authors.initials: J
authors.lastname: Schiffer
authors.forename: Meredith
authors.initials: M
authors.lastname: Kennedy
authors.forename: Joanne V
authors.initials: JV
authors.lastname: Mei
authors.forename: W Harry
authors.initials: WH
authors.lastname: Hannon
mesh_terms: D019326:17-alpha-Hydroxyprogesterone / Q000032:analysis; D000312:Adrenal Hyperplasia, Congenital / Q000175:diagnosis*; D000735:Androstenedione / Q000032:analysis; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis; D007231:Infant, Newborn; D015997:Neonatal Screening / Q000379:methods* / Q000592:standards; D010865:Pilot Projects; D013256:Steroids / Q000032:analysis*; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D013256:Steroids; D000735:Androstenedione; D019326:17-alpha-Hydroxyprogesterone; D006854:Hydrocortisone