Abstract
Background: The main goal of this work was to describe the analytical characteristics of an enzymatic photometric test for carnitine determination and its automation using an Olympus analyzer.
Methods: We used a test from Roche intended for manual processing and tried to apply it for use on an Olympus AU 400 analyzer. The analytical parameters of our modified technique were determined using external quality controls and kit controls, and by measurements in venous blood samples from 85 chronically hemodialyzed patients (before and after hemodialysis) and from 68 healthy blood donors serving as controls.
Results: A reference value for free carnitine was estimated parametrically as 40.1±17.8μmol/L. The mean bias for eight control measurements was 5.1%. Sensitivity was calculated as the limit of quantification at 2.6μmol/L. The intra-assay coefficient of variation was 2.4%. The inter-assay coefficient of variation was 8.3%. Analytical recovery was 101.8%, 99.5% and 95.4%.
Conclusions: The main advantages of our automated method in comparison to the original manual method are the smaller amounts of samples, reagents and diluents required and the shorter analysis time. As hemodialysis patients often suffer from carnitine deficiency, we conclude that its determination may be helpful for diagnostic verification.
Clin Chem Lab Med 2006;44:983–6.
References
1. Bremer J. Carnitine – metabolism and functions. Physiol Rev 1983; 63:1420–80.10.1152/physrev.1983.63.4.1420Search in Google Scholar
2. Vaz FM, Wanders RJ. Carnitine biosynthesis in mammals. Biochem J 2002; 361:417–29.10.1042/bj3610417Search in Google Scholar
3. Cibulka R. Metabolic effects of carnitine and its role in medicine. Klin Biochem Metab 2005; 13:24–8.Search in Google Scholar
4. Savica V, Calvani M, Benatti P, Santoro D, Monardo P, Peluso G, et al. Carnitine system in uremic patients: molecular and clinical aspects. Semin Nephrol 2004; 24:464–8.10.1016/j.semnephrol.2004.06.023Search in Google Scholar
5. Battistella PA, Angelini C, Vergani L, Bertoli M, Lorenzi S. Carnitine deficiency induced during hemodialysis. Lancet 1978; 1:939.10.1016/S0140-6736(78)90714-6Search in Google Scholar
6. Bohmer T, Bergrem H, Eiklid K. Carnitine deficiency induced during intermittent haemodialysis for renal failure. Lancet 1978; 1:126–8.10.1016/S0140-6736(78)90422-1Search in Google Scholar
7. Evans AM, Faull R, Fornasini G, Lemanowicz EF, Longo A, Pace S, et al. Pharmacokinetics of L-carnitine in patients with end-stage renal disease undergoing long-term hemodialysis. Clin Pharmacol Ther 2000; 68:238–49.10.1067/mcp.2000.108850Search in Google Scholar
8. Goral S. Levocarnitine's role in the treatment of patients with end-stage renal disease: a review. Dial Transplant 2001; 30:530–8.Search in Google Scholar
9. Vesela E, Racek J, Trefil L, Jankovych V, Pojer M. Effect of L-carnitine supplementation in hemodialysis patients. Nephron 2001; 88:218–23.10.1159/000045993Search in Google Scholar
10. Wieland OH, Deufel T, Paetzke-Brunner I. Free and esterified carnitines: colorimetric method. In: Bergmeyer HU, editor. Methods of enzymatic analysis, Vol. VIII, 3rd ed. Weinheim: VCH Verlag, 1985:481–8.Search in Google Scholar
11. Roche Diagnostics GmbH. Roche Applied Science. http://www.roche-applied-science.com/pack-insert/11242008001a.pdf.Search in Google Scholar
12. Thomas L. Clinical laboratory diagnostics, 1st ed. Frankfurt: TH Books Verlagsgesellschaft mbH, 1998:203.Search in Google Scholar
13. Eknoyan G, Latos L, Lindberg J. Practice recommendations for the use of L-carnitine in dialysis-related carnitine disorder. Am J Kidney Dis 2003; 41:868–76.10.1016/S0272-6386(03)00110-0Search in Google Scholar
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