scholarly journals Tandem Mass Spectrometric Analysis for Amino, Organic, and Fatty Acid Disorders in Newborn Dried Blood Spots

2001 ◽  
Vol 47 (11) ◽  
pp. 1945-1955 ◽  
Author(s):  
Thomas H Zytkovicz ◽  
Eileen F Fitzgerald ◽  
Deborah Marsden ◽  
Cecilia A Larson ◽  
Vivian E Shih ◽  
...  
Keyword(s):  
Amino Acid ◽  
Multiple Reaction Monitoring ◽  
Dried Blood Spots ◽  
Spectrometric Analysis ◽  
Tandem Mass ◽  
Predictive Values ◽  
Screening Programs ◽  
Blood Spots ◽  
Chain Acyl ◽  
Tandem Mass Spectrometric

Abstract Background: Tandem mass spectrometry (MS/MS) is rapidly being adopted by newborn screening programs to screen dried blood spots for >20 markers of disease in a single assay. Limited information is available for setting the marker cutoffs and for the resulting positive predictive values. Methods: We screened >160 000 newborns by MS/MS. The markers were extracted from blood spots into a methanol solution with deuterium-labeled internal standards and then were derivatized before analysis by MS/MS. Multiple reaction monitoring of each sample for the markers of interest was accomplished in ∼1.9 min. Cutoffs for each marker were set at 6–13 SD above the population mean. Results: We identified 22 babies with amino acid disorders (7 phenylketonuria, 11 hyperphenylalaninemia, 1 maple syrup urine disease, 1 hypermethioninemia, 1 arginosuccinate lyase deficiency, and 1 argininemia) and 20 infants with fatty and organic acid disorders (10 medium-chain acyl-CoA dehydrogenase deficiencies, 5 presumptive short-chain acyl-CoA dehydrogenase deficiencies, 2 propionic acidemias, 1 carnitine palmitoyltransferase II deficiency, 1 methylcrotonyl-CoA carboxylase deficiency, and 1 presumptive very-long chain acyl-CoA dehydrogenase deficiency). Approximately 0.3% of all newborns screened were flagged for either amino acid or acylcarnitine markers; approximately one-half of all the flagged infants were from the 5% of newborns who required neonatal intensive care or had birth weights <1500 g. Conclusions: In screening for 23 metabolic disorders by MS/MS, an mean positive predictive value of 8% can be achieved when using cutoffs for individual markers determined empirically on newborns.

scholarly journals Quantification of Rifapentine, a Potent Antituberculosis Drug, from Dried Blood Spot Samples Using Liquid Chromatographic-Tandem Mass Spectrometric Analysis

2014 ◽  
Vol 58 (11) ◽  
pp. 6747-6757 ◽  
Author(s):  
Teresa L. Parsons ◽  
Mark A. Marzinke ◽  
Thuy Hoang ◽  
Erin Bliven-Sizemore ◽  
Marc Weiner ◽  
...  
Keyword(s):  
Whole Blood ◽  
Dried Blood Spots ◽  
Population Based ◽  
Spectrometric Analysis ◽  
Tandem Mass ◽  
Antituberculosis Drug ◽  
Dose Escalation Study ◽  
Drug Concentrations ◽  
Tandem Mass Spectrometric ◽  
Finger Stick

ABSTRACTThe quantification of antituberculosis drug concentrations in multinational trials currently requires the collection of modest blood volumes, centrifugation, aliquoting of plasma, freezing, and keeping samples frozen during shipping. We prospectively enrolled healthy individuals into the Tuberculosis Trials Consortium Study 29B, a phase I dose escalation study of rifapentine, a rifamycin under evaluation in tuberculosis treatment trials. We developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying rifapentine in whole blood on dried blood spots (DBS) to facilitate pharmacokinetic/pharmacodynamic analyses in clinical trials. Paired plasma and whole-blood samples were collected by venipuncture, and whole blood was spotted on Whatman protein saver 903 cards. The methods were optimized for plasma and then validated for DBS. The analytical measuring range for quantification of rifapentine and its metabolite was 50 to 80,000 ng/ml in whole-blood DBS. The analyte was stable on the cards for 11 weeks with a desiccant at room temperature and protected from light. The method concordance for paired plasma and whole-blood DBS samples was determined after correcting for participant hematocrit or population-based estimates of bias from Bland-Altman plots. The application of either correction factor resulted in acceptable correlation between plasma and whole-blood DBS (Passing-Bablok regression corrected for hematocrit;y= 0.98x+ 356). Concentrations of rifapentine may be determined from whole-blood DBS collected via venipuncture after normalization in order to account for the dilutional effects of red blood cells. Additional studies are focused on the application of this methodology to capillary blood collected by finger stick. The simplicity of processing, storage, shipping, and low blood volume makes whole-blood DBS attractive for rifapentine pharmacokinetic evaluations, especially in international and pediatric trials.

scholarly journals Measurement of total homocysteine in plasma and blood spots using liquid chromatography-tandem mass spectrometry: comparison with the plasma Abbott IMx method

2003 ◽  
Vol 40 (2) ◽  
pp. 161-165 ◽  
Author(s):  
Steven J. McCann ◽  
Scott Gillingwater ◽  
Brian G. Keevil ◽  
Donald P. Cooper ◽  
Michel R. Morris
Keyword(s):  
Sensitivity And Specificity ◽  
Plasma Concentrations ◽  
Dried Blood Spots ◽  
Dried Blood Spot ◽  
Tandem Mass ◽  
Blood Spots ◽  
Plasma Thcy ◽  
Total Homocysteine ◽  
Tandem Mass Spectrometric ◽  
Blood Spot

Background: Current sampling for total homocysteine (tHcy) is problematic, requiring plasma separation within 15 min. The aim of this study was to develop a liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method for the measurement of tHcy in plasma and dried blood spots and to determine whether the dried blood spot concentration could be used to predict plasma concentrations of tHcy. Methods: LC-MS/MS methodology was optimized to measure tHcy in plasma and dried blood spots. Fifty blood samples collected from heart transplant patients were used to form dried blood spots and for plasma analysis. Plasma tHcy was also measured using the Abbott IMx1 method and values were compared to the tHcy concentrations determined in plasma and dried blood spots using LC-MS/MS methodology. Results: The plasma tHcy LC-MS/MS results compared well with the IMx values: LC-MS/MS=1·18(IMx)-0·44 ( r2=0·915). The within-batch precision ( n =10) of the plasma LC-MS/MS method was < 2·0% at 14·6 and 37·7 µmol/L, respectively; the between-batch precision ( n=10) was 5·0 and 8·0%, respectively, at these concentrations. The method was found to be sensitive down to 1 µmol/L and linear up to at least 100 µmol/L. Dried blood spot LC-MS/MS results were considerably lower than the plasma IMx values ( P < 0·0001): dried blood spot LC-MS/MS=0·33IMx+1·77 ( r2=0·682). The within-batch precision ( n=20) of the dried blood spot LC-MS/MS method was 7·3% and 4·7% at concentrations of 4·0 and 7·9 µmol/L, respectively; the between-batch precision was 12·6% and 7·9% at concentrations of 5·1 and 8·0 µmol/L, respectively. To assess whether dried blood spots are suitable as a screening test to predict plasma tHcy concentrations, arbitary cut-off levels were compared. If it is assumed that a plasma tHcy concentration of >15 µmol/L is raised, a dried blood spot result of >6·8 µmol/L has a sensitivity and specificity in detecting a raised plasma tHcy of 83·3% and 96·2%, respectively, and a positive and negative predictive value of 95% and 86%, respectively, with an efficiency of 90%. Use of a dried blood spot cut-off concentration of 6·2 µmol/L for predicting high plasma tHcy concentrations (above 15 µmol/L) has a sensitivity and specificity of 95·8% and 73·1%, respectively, positive and negative predictive values of 76% and 95%, respectively, and an efficiency of 84%. Conclusions: We have developed a precise and accurate LC-MS/MS method for measuring plasma tHcy concentrations, which uses a small volume of plasma and is suitable for routine use. A satisfactory LC-MS/MS method for the measurement of tHcy in dried blood spots was also developed; this method might be useful in routine screening for raised plasma concentrations of tHcy.

scholarly journals Validation of Accuracy-based Amino Acid Reference Materials in Dried-Blood Spots by Tandem Mass Spectrometry for Newborn Screening Assays

1999 ◽  
Vol 45 (8) ◽  
pp. 1269-1277 ◽  
Author(s):  
Donald H Chace ◽  
Barbara W Adam ◽  
S Jay Smith ◽  
J Richard Alexander ◽  
Steven L Hillman ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Amino Acids ◽  
Amino Acid ◽  
Tandem Mass Spectrometry ◽  
Newborn Screening ◽  
Dried Blood Spots ◽  
Tandem Mass ◽  
Blood Spots ◽  
Amino Acid Contents ◽  
Amino Acid Concentrations

Abstract Background: Advances in technology and the earlier release of newborns from hospitals have pressed the demand for accurate calibration and improved interlaboratory performance for newborn screening tests. As a first step toward standardization of newborn screening aminoacidopathy tests, we have produced six-pool sets of multianalyte dried-blood-spot amino acid reference materials (AARMs) containing predetermined quantities of five amino acids. We describe here the production of the AARMs, validation of their amino acid contents, and characterization of their homogeneity and their stability in storage. Methods: To each of six portions of a pool of washed erythrocytes suspended in serum we added Phe (0–200 mg/L), Leu (0–200 mg/L), Met (0–125 mg/L), Tyr (0–125 mg/L), and Val (0–125 mg/L). Six-pool sets (1300) were prepared, dried, and packaged. We used isotope-dilution mass spectrometry to estimate the endogenous amino acid concentrations of the AARMs and validate their final amino acid concentrations. We used additional tandem mass spectrometry analyses to examine the homogeneity of amino acid distribution in each AARM, and HPLC analyses to evaluate the stability of the amino acid contents of the AARMs. Results: The absolute mean biases across the analytic range for five amino acids were 2.8–9.4%. One-way ANOVAs of the homogeneity results predicted no statistically significant differences in amino acid concentrations within the blood spots or within the pools (P &gt;0.05). Regression slopes (0 ± 0.01) for amino acid concentrations vs storage times and their P values (&gt;0.05) showed no evidence of amino acid degradation at ambient temperatures, 4 °C, or −20 °C during the intervals tested. Conclusion: The validation, homogeneity, and stability of these blood spots support their use as a candidate national reference material for calibration of assays that measure amino acids in dried-blood spots.

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

2006 ◽  
Vol 52 (3) ◽  
pp. 482-487 ◽  
Author(s):  
Johannes Sander ◽  
Nils Janzen ◽  
Michael Peter ◽  
Stefanie Sander ◽  
Ulrike Steuerwald ◽  
...  
Keyword(s):  
Newborn Screening ◽  
False Positive ◽  
False Negative ◽  
Internal Standard ◽  
Mass Spectrometric ◽  
Absolute Methanol ◽  
Tandem Mass ◽  
Screening Programs ◽  
Blood Spots ◽  
Tandem Mass Spectrometric

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 ≤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 56th hours 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.

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