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153 - To assay the concentration of Total and Free Testosterone may be harmful to health: the 2007 Position Statement of the Endocrine Society

Autor(s): Romolo M. Dorizzi

Issue: RIMeL - IJLaM, Vol. 3, N. 3, 2007 (MAF Servizi srl ed.)

Page(s): 153-163

Serum total testosterone and free testosterone levels are being measured in thousands laboratories worldwide, but since there is no universally recognized testosterone calibrating standard different laboratories frequently produce variable results. Since inaccurate results are unhelpful at best, or harmful in worst-case situations, the Endocrine Society, in order to improve this situation, appointed a panel of five experts, chaired by Dr. Rosner, to examine published data and to make the proper recommendations. They published in the February 2007 issue of the Journal of Clinical Endocrinology & Metabolism a Position Statement with the title “Utility, Limitations, and Pitfalls in Measuring Testosterone: An Endocrine Society Position Statement,” that underwent many rounds of review by the expert panel, review and approval by the Council, and peer review by The Journal. The content of the paper has been here summarized and further specific references from the laboratory field has been added in order to promote among the laboratorians the knowledge of the Statement. In our opinion the laboratory professionals should accept and embrace its recommendations. The major conclusions are as: 1) laboratory proficiency testing should be based on the ability to measure accurately and precisely samples containing known concentrations of testosterone, not only upon agreement with others using the same method. 2) When such standardization is in place, normative values for total and free testosterone should be established for both genders and for children taking into account the many variables that influence serum testosterone concentration. Moreover, other recommendations should be implemented in the interim. According to us the most urgent are: 1) The laboratorians and the clinicians should know the type and quality of the assay that is being used, and reference intervals for that assay should be properly established by each laboratory in collaboration with endocrinologists, using well defined and characterized populations. 2) Direct assays poorly measure low testosterone concentrations and should be avoided. 3) The recommended screening test for male hypogonadism is the measurement of serum Total Testosterone on more than one morning sampling. 4) Calculated Free Testosterone, measured using high quality Testosterone and SHBG assays with well defined reference intervals, is the most useful, clinically sensitive marker of hyperandrogenemia in women.

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