Open Access

HOW I DO IT

Acritical appraisal of accuracy and cost of laboratory methodologies for the diagnosis of hypogonadism: the role of free testosterone assays

Alvaro Morales, Christine P. Collier, Albert F. Clark

Queen’s University, Kingston, Ontario, Canada
Address correspondence to Dr. Alvaro Morales, 59 Lakeshore Blvd., Kingston, ON K7M 6R4 Canada

Canadian Journal of Urology 2012, 19(3), 6314-6318.

Abstract

The biochemical diagnosis of male hypogonadism remains a controversial issue. The problem is compounded by the variety of laboratory assays available to measure serum testosterone (T) and the limited understanding, among clinicians, of their relative diagnostic validity. It is widely accepted that only the testosterone not bound to sex hormone-binding globulin is metabolically active. Therefore, for diagnostic purposes, it is common practice to order the measurement of free T (FT) or bioavailable T (BAT).
Our objective is to describe the methods available for measuring FT and to review the literature to determine the relevance of ordering FT as a diagnostic laboratory tool in cases of suspected hypogonadism. We also provide our biochemical approach in evaluating men with testosterone deficiency. The limited information available in this regard is frequently confined to the biochemistry literature.
The few reliable studies indicate that analog-based measurement of FT offers no diagnostic or financial advantage over automated assay for total T. The manuscript also describes “How we do it.” For optimal diagnostic accuracy and financial responsibility, total T and calculated FT (cFT) should be the tests employed for initial and confirmatory diagnosis, respectively. Measurement of bioavailable T is an alternative option but not germane to the points to which we are calling attention in this paper.
While clinicians should be discouraged from ordering FT assays, laboratories performing it should indicate what method was used and warn about possible reliability concerns. FT assays should no longer be a reimbursable test.

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Keywords

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