Received on August 26, 2005
Accepted on December 22, 2005

Endocrinology and Metabolism

Newborn Screening for Hepatorenal Tyrosinemia: Tandem Mass Spectrometric Quantification of Succinylacetone

¹ Screening Laboratory, Hannover, Germany
² Department of General Paediatrics, University Children's Hospital, University of Düsseldorf, Düsseldorf, Germany
³ Department of Paediatrics, Klinikum am Steinenberg, Steinenberg, Germany
⁴ Department of Paediatrics, Medizinische Hochschule, Hannover, Germany

^* To whom correspondence should be addressed. E-mail: j.sander{at}metabscreen.de.

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 5 µmol/L. With a cutoff of 10 µmol/L, no false-positive results were obtained. In 2 patients, the succinylacetone concentrations in the dried blood spots from the 36th and the 56th hour of life were 152 and 271 µmol/L, respectively, and the tyrosine concentrations were 54 and 129 µmol/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 µmol/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.