PERFORMANCE OF SUCCINYLACETONE ASSAYS AND THEIR ASSOCIATED PROFICIENCY TESTING OUTCOMES
Published Date:Aug 11 2012
Source:Clin Biochem. 45(18):1658-1663.
Dried Blood Spots
Dried Blood Spot Testing
Laboratory Proficiency Testing
Tandem Mass Spectrometry
Tyrosinemia Type I
Pubmed Central ID:PMC4557813
Funding:CC999999/Intramural CDC HHS/United States
Succinylacetone (SUAC) is the primary metabolic marker for hepatorenal tyrosinemia.
Materials and Methods
We used results reported for dried-blood-spot proficiency testing (PT) specimens and hepatorenal tyrosinemia patients’ newborn screening (NBS) samples to demonstrate analytic biases in SUAC recoveries and differences in presumptive clinical classifications.
SUAC recoveries from non-kit and NeoBase™ kit tandem mass spectrometry methods were markedly different. Kit users that set high cutoff values submitted discordant clinical assessments of “within normal limits” for PT specimens enriched with 10–15 µmol SUAC/L blood. SUAC levels in tyrosinemia patients’ NBS samples analyzed by NeoBase™ kit were lower than those in samples analyzed by non-kit methods.
Analytic biases in SUAC recoveries were consistent from 2009–2011. Discordant clinical assessments of PT specimens were associated with high cutoff values for NeoBase™ kit results. Method-related differences in SUAC concentrations of tyrosinemia patients’ samples were consistent with those of PT specimens.
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