More on the Analog Free-Testosterone Assay

The analog free testosterone assay: are the results in men clinically useful?

Men with low testosterone concentrations are usually hypogonadal. However, because variations in the testosterone transport protein, sex hormone-binding globulin (SHBG), directly influence the total testosterone concentration, confirmation of a low testosterone with a measurement of free testosterone or "bioavailable" testosterone (BAT) is recommended. In the present study, we examined the rela...

Free testosterone measurement by the analog displacement direct assay: old concerns and new evidence.

Fritz and coworkers (1 ) have provided data arguing against the validity of a popular analog-based direct assay for free testosterone (T). Their rigorous dissection of characteristics of the assay and use of carefully defined solutions demonstrates that the assay correlates generally with total T but does not measure dialyzable T; this observation is consistent with prior reservations about thi...

Analog-based free testosterone test results linked to total testosterone concentrations, not free testosterone concentrations.

BACKGROUND Analog-based free testosterone test results, sex hormone binding globulin (SHBG) concentrations, and total testosterone concentrations are somehow related. This study used new experiments to clarify these relationships. METHODS An analog-based free testosterone immunoassay and a total testosterone immunoassay were applied to well-defined fractions of serum testosterone. First, they...

Analog vs non-analog free T4 assay: effect of sample dilution.

Effect of albumin on results of an "improved" analog-type assay for free thyroxin.

The paper by Sykes et al. (1) on the effect of phospholipase C on high-molecular-mass alkaline phosphatase in serum contains nomenclatural errors. In the Abstract, an Enzyme Comnussion number (EC 3.1.4.3) is given for the phospholipase C of Bacillus cereus; this is not the Enzyme Commission number of the phospholipase C responsible for the effect reported (i.e., the release of liver alkaline ph...