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This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: clinchem.2008.105841v1 54/8/1290    most recent Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Thienpont, L. M. Articles by Sluss, P. M. Search for Related Content PubMed PubMed Citation Articles by Thienpont, L. M. Articles by Sluss, P. M. Related Collections Endocrinology and Metabolism

State-of-the-Art of Serum Testosterone Measurement by Isotope Dilution–Liquid Chromatography– Tandem Mass Spectrometry

¹ Laboratory for Analytical Chemistry, Faculty of Pharmaceutical Sciences, Gent University, Gent, Belgium; ² Abbott Diagnostics, Dartford, Kent, UK; ³ Abbott Diagnostics, Abbott Park, IL; ⁴ Department of Biochemistry, University Hospital of South Manchester, Manchester, UK; ⁵ ARUP Laboratories, Salt Lake City, UT; ⁶ Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT; ⁷ Esoterix Inc., Calabasas Hills, CA; ⁸ Department of Clinical Biochemistry, Old Medical School, Leeds General Infirmary, Leeds, UK; ⁹ Clinical Pathology Core Laboratory, Massachusetts General Hospital, Boston, MA.

^aAddress correspondence to this author at: Laboratory for Analytical Chemistry, Faculty of Pharmaceutical Sciences, Gent University, Harelbekestraat 72, B-9000 Gent, Belgium. Fax +32-9-264.81.98; e-mail linda.thienpont{at}ugent.be.

Background: The recent interest of clinical laboratories in developing serum testosterone assays based on isotope dilution–liquid chromatography–tandem mass spectrometry (ID-LC-MS/MS) stems from the lack of accuracy of direct immunoassays. In this study, we assessed the accuracy and state of standardization (traceability) of 4 published ID-LC-MS/MS procedures in a method comparison with an ID–gas chromatography (GC)–MS reference measurement procedure listed in the database of the Joint Committee for Traceability in Laboratory Medicine.

Methods: The study used 58 specimens from different patient categories. Each specimen was measured in triplicate (ID-LC-MS/MS) and quadruplicate (ID-GC-MS) in independent runs.

Results: The testosterone concentrations by ID-GC-MS were 0.2–4.4 nmol/L (women), 0.2–2.0 nmol/L (hypogonadal man), and 10.1–31.3 nmol/L (normogonadal men). For ID-GC-MS, the CV was nearly constant, with a median of 1.0%; for ID-LC-MS/MS, it was concentration-dependent, with a median of up to 8%. Weighted Deming regression gave mean slopes, intercepts, and correlation coefficients of 0.90–1.11, –0.055–0.013 nmol/L, and 0.993–0.997, respectively. The % difference plot showed between 7% and 26% of the results outside a total error limit of 14%, with median deviations from ID-GC-MS between –9.6 and 0.4%.

Conclusions: This study demonstrated fairly good accuracy and standardization of the tested ID-LC-MS/MS procedures. Performance differences between procedures were evident in some instances, due to improper calibration and between-run calibration control. This emphasizes the need for thorough validation, including traceability, of new ID-LC-MS/MS procedures.

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