Liquid chromatography–tandem mass spectrometry method for the simultaneous determination of δ-ALA, tyrosine and creatinine in biological fluids
2004; Elsevier BV; Volume: 350; Issue: 1-2 Linguagem: Inglês
10.1016/j.cccn.2004.08.009
ISSN1873-3492
AutoresNatalia Felitsyn, George N. Henderson, Margaret O. James, Peter W. Stacpoole,
Tópico(s)Neonatal Health and Biochemistry
ResumoSeveral acquired and congenital human disorders perturb the concentrations of delta-aminolevulinate (δ-ALA), creatinine and tyrosine in biological fluids. There is currently no facile, sensitive and specific method to measure these analytes simultaneously. We developed an LC-MS/MS method to quantify δ-ALA, creatinine and tyrosine in urine that requires minimal sample preparation and no derivatization. The method is also applicable to the analysis of tyrosine in plasma. All calibration plots were linear, with R2≥0.996. Intra- and interday CVs were <10%. The limit of quantitation for δ-ALA was ∼0.1 μmol/l, and for creatinine and tyrosine it was well below the lowest measured physiological concentrations. The method was applied to analyze urine from 75 healthy volunteers and 43 patients with hereditary tyrosinemia type I (HT I). The mean urinary concentration of δ-ALA in patients (38±35 μmol/l, 53±30 mg/g creatinine) was higher than that measured in healthy subjects (5.5±2.6 μmol/l, 0.9±0.2 mg/g creatinine; p<0.001). Treatment with 2-(2-nitro-4-trifluoromethylbenzyl)-1,3-cyclohexanedione (NTBC), an inhibitor of an early step in tyrosine catabolism, decreased urinary δ-ALA (6.4±4.8 μmol/l, 13±24 mg/g creatinine; p<0.001). The average plasma tyrosine concentration in healthy volunteers (56±14 μmol/l) was within normal reference interval used in clinical practice. The method is simple, specific and precise and allows simultaneous quantitation of δ-ALA, creatinine and tyrosine at concentrations present under physiological or pathophysiological conditions.
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