Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-2 (of 2 Records) |
Query Trace: Meredith NK[original query] |
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Performance of succinylacetone assays and their associated proficiency testing outcomes
Adam BW , Hall EM , Meredith NK , Lim TH , Haynes CA , De Jesus VR , Hannon WH . Clin Biochem 2012 45 (18) 1658-63 BACKGROUND: 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. RESULTS: 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 10-15mcmol SUAC/L in blood. SUAC levels in tyrosinemia patients' NBS samples analyzed by NeoBase kit were lower than those in samples analyzed by non-kit methods. CONCLUSIONS: From 2009 to 2011, analytic biases in SUAC recoveries were consistent. 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. |
Proficiency testing outcomes of 3-hydroxyisovalerylcarnitine measurements by tandem mass spectrometry in newborn screening
Lim TH , De Jesus VR , Meredith NK , Sternberg MR , Chace DH , Mei JV , Hannon WH . Clin Chim Acta 2010 412 631-5 BACKGROUND: The use of tandem mass spectrometry (MS/MS) for the analysis of amino acids and acylcarnitines from dried-blood spots (DBS) has become routine practice in newborn screening laboratories. The Newborn Screening Quality Assurance Program (NSQAP) added 3-hydroxyisovalerylcarnitine (C5OH) into its routine quality control and proficiency testing (PT) DBS materials for MS/MS to assure the quality of C5OH screening. We report the results from NSQAP evaluations for C5OH-enriched DBS, and summarize participant screening practices based on their analytical methods. METHODS: NSQAP prepared C5OH-enriched DBS materials for its participants. Laboratories reported quantitative and qualitative results. Bias plots of quantitative results were constructed using reported data and the results were sorted by analytical method. RESULTS: NSQAP participants reported PT specimen 3964 as outside of normal limits for C5OH. The mean C5OH value for derivatized and non-derivatized methods was 2.80 and 2.67mumol/l, respectively. Reported data from other specimens showed a similar trend in derivatized vs. non-derivatized assay results. Differences in C5OH quantitative values were observed among laboratories using different internal standards. CONCLUSIONS: C5OH MS/MS measurements in DBS assays varied by method and the choice of internal standards. The use of NSQAP's DBS materials allows harmonization of C5OH measurements by newborn screening laboratories worldwide. |
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