title: Newborn screening for hepatorenal tyrosinemia: Tandem mass spectrometric quantification of succinylacetone.
abstract: BACKGROUND
  False-positive and false-negative results occur in current newborn-screening programs for hepatorenal tyrosinemia, which measure tyrosine concentrations in blood spots, sometimes in combination with other metabolites, including succinylacetone. We present our experience with a newly described method for succinylacetone quantification in routine newborn screening.
  
  
  METHODS
  Succinylacetone was extracted from blood spots that had already been extracted with absolute methanol for acylcarnitine and amino acid analysis. The solvent was acetonitrile-water (80:20 by volume) containing formic acid, hydrazine hydrate, and 100 nmol/L 5,7-dioxooctanoic acid as internal standard. Analysis was performed by tandem mass spectrometry in a separate run.
  
  
  RESULTS
  Of 61,344 samples, 99.6% had succinylacetone concentrations < or =5 micromol/L. With a cutoff of 10 micromol/L, no false-positive results were obtained. In 2 patients, the succinylacetone concentrations in the dried blood spots from the 36th and 56th hours of life were 152 and 271 micromol/L, respectively, and the tyrosine concentrations were 54 and 129 micromol/L. Hepatorenal tyrosinemia was subsequently confirmed in both patients. Retrospective analysis of the neonatal screening samples of 2 additional known patients revealed increased succinylacetone concentrations of 46 and 169 micromol/L, respectively.
  
  
  CONCLUSIONS
  Tandem mass spectrometric quantification directly from residual blood spots is a useful method for the early detection of hepatorenal tyrosinemia in newborn-screening programs.
authors.affiliation: Screening Laboratory, Hannover, Germany. j.sander@metabscreen.de
authors.forename: Johannes
authors.initials: J
authors.lastname: Sander
authors.forename: Nils
authors.initials: N
authors.lastname: Janzen
authors.forename: Michael
authors.initials: M
authors.lastname: Peter
authors.forename: Stefanie
authors.initials: S
authors.lastname: Sander
authors.forename: Ulrike
authors.initials: U
authors.lastname: Steuerwald
authors.forename: Ute
authors.initials: U
authors.lastname: Holtkamp
authors.forename: Bernd
authors.initials: B
authors.lastname: Schwahn
authors.forename: Ertan
authors.initials: E
authors.lastname: Mayatepek
authors.forename: Friedrich K
authors.initials: FK
authors.lastname: Trefz
authors.forename: Anibh M
authors.initials: AM
authors.lastname: Das
mesh_terms: D001800:Blood Specimen Collection; D005260:Female; D006537:Heptanoates / Q000097:blood*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D015997:Neonatal Screening; D011446:Prospective Studies; D012189:Retrospective Studies; D020176:Tyrosinemias / Q000175:diagnosis*
chemical_list: D006537:Heptanoates; C020804:succinylacetone