Clinical Chemistry Link to Randox Laboratories Web Site
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Clinical Chemistry 47: 575-583, 2001;
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Supplemental Tables
Right arrow Submit an electronic Letter to
the Editor about this paper
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via ISI Web of Science (4)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Venta, R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Venta, R.
Related Collections
Right arrow General Clinical Chemistry
Right arrow Pediatric Clinical Chemistry
Right arrow Nutrition
(Clinical Chemistry. 2001;47:575-583.)
© 2001 American Association for Clinical Chemistry, Inc.

Articles

Year-Long Validation Study and Reference Values for Urinary Amino Acids Using a Reversed-Phase HPLC Method

Rafael Venta1

1 Servicio de Análisis Clínicos, Hospital San Agustín, Avilés, and Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, Camino de Heros 4, 33400 Avilés, Asturias, Spain. Fax 34-985-123-025; e-mail r.venta.000{at}recol.es.

Background: Reversed-phase HPLC (RP-HPLC) has become an alternative to ion-exchange chromatography for amino acid analysis in biological fluids. However, validation studies for its urine application are limited, and the corresponding reference values have not been reported extensively. We studied the long-term performance of a commercial HPLC method for urine amino acid analysis and established specific age-related reference values for urine amino acid excretion.

Methods: Method performance was continuously assessed by recovery and precision studies with urine samples and controls, respectively. Healthy individuals were prospectively analyzed throughout a 5-year period. Excretion of individual amino acids, expressed as mmol/mol of creatinine, was included in six age-related groups for random urine samples (0–1 month, 1–12 months, 1–3 years, 3–8 years, 8–16 years, and >16 years) and in two groups for 24-h urine collections (8–16 years and >16 years).

Results: Over a 1-year period, CVs for retention times were <0.5% and 3.3% for within- and between-run imprecision, respectively. For amino acid concentrations, within-run CVs were 2.9–17% and between-run CVs were 7.1–46% for the same period. Amino acid recoveries were 78–122%. Reference intervals for 35 amino acids were calculated and compared with the concentrations observed in patients diagnosed with specific pathologies. A few statistically significant differences were found between the reference intervals derived using random and 24-h urine collections.

Conclusions: Long-term reliability of the RP-HPLC method for urine amino acid analysis has been demonstrated. Representative age-related reference intervals for the RP-HPLC method in both random urine and 24-h urine collections have been established, and their feasibility for diagnosis of aminoaciduria has been shown. These intervals could serve as a guide for laboratories changing to HPLC methods.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2001 by the American Association for Clinical Chemistry.