Sophie Hepburn (Presenter)
Prince of Wales Hospital
Bio: I trained as a Clinical Scientist specialising in Clinical Biochemistry between 2004 and 2007 achieving a Masters and professional registration in this discipline. I continued to work as a Clinical Scientist in three large teaching hospitals in the UK until my move to Australia in 2012. Since arriving in Australia I have worked at the national accreditation body for medical laboratories (NATA) and as a Clinical Scientist in private and public health departments. I have recently moved into a role as lead research officer for reference interval and endocrine-based research projects at a public health network in Sydney, with an emphasis on transferring methods from immunoassay to LC-MS/MS.
Authorship: Sophie Hepburn (1), Michael JP Wright (1), Conchita Boyder (2), Renee C Sahertian (1), Ben Lu (1), Rui Zhang (2), Chris P White (1), Andrea R Horvath (1)
(1) SEALS Clinical Chemistry and Endocrinology, Prince of Wales Hospital, Sydney, NSW, Australia. (2) PathWest, Queen Elizabeth II Medical Centre, Perth, WA, Australia
| Short Abstract We examined the stability of four sex steroids in serum stored at 4°C for up to 5 days. Serum collected into gel and non-gel containing tubes was analysed by LC-MS/MS for testosterone, androstenedione, 17-hydroxyprogesterone (n=20); and estradiol (n=27). Differences in measurand concentration at day 0 and following storage (day 1 and day 5) were evaluated for statistical / clinical significance. Androstenedione concentrations in gel-containing tubes were reduced by an average of 14% by day 5 (p<0.001), determined to be clinically significant. In addition, estradiol and testosterone concentrations were significantly increased in plain serum tubes by day 1 (p<0.01). |
Long Abstract
Introduction:
Consideration of pre-analytical factors is important in laboratory settings especially where delays in testing occur (due to transportation) or where add-on testing is acceptable practice. Pre-analytical error is often assumed to be negligible, but this is not always the case, and even a small change in measurand concentration could impact the final result if not all sources of error are identified and minimized. A pilot study showing a decrease in androstenedione concentration in serum collected into gel-containing serum tubes triggered an investigation of the effect of specimen collection tubes on steroid hormone stability.
Methods:
Two tube types were examined: BD Vacutainer® SST II Advance gel tube and BD Vacutainer® Serum Tube with no gel barrier. Forty-seven serum samples from apparently healthy volunteers (age range, 22-69 years; 19 males and 28 females) were collected and analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) for testosterone, androstenedione, 17-hydroxyprogesterone (n=20); and estradiol (n=27). Primary specimens were centrifuged once, maintained at room temperature and extracted within 2 hours for day 0 (d0) results. To assess stability at 4°C, aliquots were taken from the primary tube on day 1 (d1) and day 5 (d5) and analysed immediately. The differences in measurand concentration between tubes at d0 and following storage (d1 and d5) were evaluated for both statistical and clinical significance.
Results:
There was a progressive and statistically significant decrease in androstenedione concentration from d0 to d5 (p<0.001) in the serum gel tube compared to the plain serum tube at d0. In addition, there was a statistically significant reduction in concentration of testosterone, 17-hydroxyprogesterone and estradiol at d5 (p<0.01). Interestingly, estradiol and testosterone concentrations increased with time in plain serum tubes (p<0.01). The most stable of the measurands tested was 17-hydroxyprogesterone, which did not change by more than 4% throughout the conditions studied. Only the change in androstenedione at d5 in gel tubes was determined to be clinically significant.
Conclusions:
Serum tubes with or without a gel barrier cannot be used interchangeably for all steroid measurands. To optimize conditions and to reduce pre-analytical error we recommend the use of plain non-gel serum collection tubes for androstenedione and rapid separation of serum from cells when estradiol and testosterone are determined.
References & Acknowledgements:
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