Stability of testosterone measured in male archival serum samples by two different methods

Abstract

Objective. To investigate testosterone stability in archival serum samples stored for etiological cancer research, and compare two methods for testosterone measurements. Design and measurements. Four sets of 130 serum samples were randomly selected from male blood donors, aged 40–49 years at the time of blood draw. The sets had been stored at –25°C for 1 month, 4, 17 and 29 years, respectively, and were analyzed for testosterone, sex hormone binding globuline, follicle stimulating hormone, luteinizing hormone, sodium, albumin and cotinine. Testosterone was measured by two methods, an electrochemiluminescence immunoassay, and a liquid chromatography tandem mass spectrometry method. Results. The mean level of testosterone in the samples with the longest storage time (29 years) was substantially higher than that of the fresh samples. The two techniques gave approximately equal results for testosterone values in the range 5–27.5 nmol/L, close to normal range. Conclusions. The high mean levels of testosterone in the oldest samples suggest a downward trend over the last three decades, as any degradation during storage would tend to give the opposite result. For archival serum samples, both electrochemiluminescence immunoassay and liquid chromatography tandem mass spectrometry are applicable methods for measurement of testosterone within the expected reference range.

Key Words::

• Biological specimen bank
• immunoassay
• mass spectrometry
• serum
• testosterone

Acknowledgements

We gratefully acknowledge the technical assistance of Astrid Steiro, Hildur Tannum and Laila Gjerdalen at Department of Medical Biochemistry, Oslo University Hospital, Norway and Unni Sirum at St. Olavs Hospital, Department of Medical Biochemistry, Trondheim University Hospital, Norway. The Janus Biobank, established by the Norwegian Cancer Society and today owned by The Norwegian Cancer Registry, provided the serum samples.

The study was approved by the Regional Committee for Research Ethics in Norway.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

This work was supported by The European Union project “Cancer Control using Population-based Registries and Biobanks”, Grant number LSHC-CT-2004-503465.