Yager Claire, Wehrli Suzanne, Segal Stanton
Metabolic Research Laboratory, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
Clin Chim Acta. 2006 Apr;366(1-2):216-24. doi: 10.1016/j.cca.2005.10.015. Epub 2005 Dec 5.
Measurements of urine galactitol have been used to monitor the adequacy of diet therapy in the treatment of galactosemia. We have devised a gas chromatographic mass spectrometry (GC/MS) isotope-dilution method for the simultaneous quantification of urine galactitol and another alternate pathway product, galactonate.
We prepared trimethylsilyl (TMS) derivatives and used D-[UL-13C]galactitol and D-[UL-13C]galactonate as the internal standard for GC/MS. Results obtained with this method were compared with those determined by the established GC method for galactitol and the NMR method for galactonate. Thirty-three normal urine specimens were analyzed by the isotope dilution technique for galactitol and galactonate. Results of galactitol in 6 of these urine specimens along with 18 from classic galactosemics and 19 variant galactosemics were compared with the established GC method. Results for galactonate in 15 urine specimens from galactosemics were compared to the established NMR technique.
The method was linear up to 200 nmol with lower limits of detection of 1.1 nmol (1.75 mmol/mol creatinine) (Cr) and 0.8 nmol (1.28 mmol/mol Cr) for galactitol and galactonate, respectively. Intra- and Interassay imprecision ranged from 2.1-6.7% for galactitol and 3.5-8.0% for galactonate. The excretion of both metabolites was age dependent in both normal and galactosemics. In 12 normal urines from subjects under 1 year, values for galactitol ranged from 8-107 mmol/mol Cr, and in 7 over age 6, ranged from 2-5 mmol/mol Cr. Under 1 year, the range for galactonate was non-detectable to 231 and in the over 6 years group non-detectable to 25 mmol/mol Cr. In galactosemics under 1 year, the value for galactitol ranged from 397-743 and for galactonate 92-132 mmol/mol Cr while in nine patients over age 6 the range was 125-274 mmol/mol Cr for galactitol and 17-46 mmol/mol Cr for galactonate.
The GC/MS method enables the simultaneous determination of urine galactitol and galactonate and is precise and useful over the wide range of concentrations needed to assess the galactose burden in patients with galactosemia.
尿半乳糖醇的测定已用于监测半乳糖血症饮食治疗的充分性。我们设计了一种气相色谱 - 质谱联用（GC/MS）同位素稀释法，用于同时定量尿半乳糖醇和另一种替代途径产物半乳糖酸。
我们制备了三甲基硅烷基（TMS）衍生物，并使用D-[UL-13C]半乳糖醇和D-[UL-13C]半乳糖酸作为GC/MS的内标。将该方法获得的结果与用于半乳糖醇的既定GC方法和用于半乳糖酸的核磁共振（NMR）方法所测定的结果进行比较。采用同位素稀释技术对33份正常尿液标本进行半乳糖醇和半乳糖酸分析。将其中6份尿液标本以及18份典型半乳糖血症患者和19份变异型半乳糖血症患者的半乳糖醇结果与既定的GC方法进行比较。将15份半乳糖血症患者尿液标本中的半乳糖酸结果与既定的NMR技术进行比较。
该方法在高达200 nmol时呈线性，半乳糖醇和半乳糖酸的检测下限分别为1.1 nmol（1.75 mmol/mol肌酐（Cr））和0.8 nmol（1.28 mmol/mol Cr）。批内和批间不精密度对于半乳糖醇为2.1 - 6.7%，对于半乳糖酸为3.5 - 8.0%。在正常人和半乳糖血症患者中，两种代谢物的排泄均与年龄有关。在12份1岁以下受试者的正常尿液中，半乳糖醇值范围为8 - 107 mmol/mol Cr，在7份6岁以上受试者的尿液中，范围为2 - 5 mmol/mol Cr。1岁以下时，半乳糖酸范围为未检测到至231，在6岁以上组中为未检测到至25 mmol/mol Cr。在1岁以下的半乳糖血症患者中，半乳糖醇值范围为397 - 743，半乳糖酸为92 - 132 mmol/mol Cr，而在9名6岁以上患者中，半乳糖醇范围为125 - 274 mmol/mol Cr，半乳糖酸为17 - 46 mmol/mol Cr。
GC/MS方法能够同时测定尿半乳糖醇和半乳糖酸，并且在评估半乳糖血症患者半乳糖负荷所需的广泛浓度范围内准确且有用。
