Wide variability in laboratory reference values for serum testosterone.

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http://www.ncbi.nlm.nih.gov/pubmed/17100942

J Sex Med. 2006 Nov;3(6):1085-9.

Wide variability in laboratory reference values for serum testosterone.

Lazarou S, Reyes-Vallejo L, Morgentaler A.

Harvard Medical School, Division of Urology, Beth Israel Deaconess Medical

Center, Boston, MA, USA.

Abstract

INTRODUCTION: The laboratory determination of testosterone levels consistent

with a diagnosis of hypogonadism is complicated by the availability of multiple

testosterone assays and varying reference ranges.

AIM: To assess current laboratory practices regarding availability of

testosterone assays and use of reference values.

METHODS: A telephone survey of 12 academic, 12 community medical laboratories,

and one national laboratory.

MAIN OUTCOME MEASURES: Types of androgen assays offered and determination of

reference values.

RESULTS: All of the academic and eight of the community centers performed total

testosterone testing. Free testosterone was performed in-house by six of the 12

academic and one community center. Testing for bioavailable testosterone, free

androgen index, and percent free testosterone was performed in-house by no more

than two centers. There were eight and four different assays used for total and

free testosterone, respectively. One national laboratory offered equilibrium

dialysis measurement of free testosterone. Of the 25 labs, there were 17 and 13

different sets of reference values for total and free testosterone,

respectively. The low reference value for total testosterone ranged from 130 to

450 ng/dL (350% difference), and the upper value ranged from 486 to 1,593 ng/dL

(325% difference). Age-adjusted reference values were applied in four centers

for total testosterone and in seven labs for free testosterone. All reference

values were based on a standard statistical model without regard for clinical

aspects of hypogonadism. Twenty-three of the 25 lab directors responded that

clinically relevant testosterone reference ranges would be preferable to current

standards.

CONCLUSIONS: Laboratory reference values for testosterone vary widely, and are

established without clinical considerations.

So - again I ask - how do we determine what our testosterone levels should be if

laboratory reference values are established WITHOUT clinical considerations??