Dehydroepiandrostenedione sulphate interferes in many direct immunoassays for testosterone

In response to a report that the Abbott Architect direct testosterone immunoassay was affected by dehydroepiandrostenedione sulphate (DHEAS) cross-reactivity, this study investigated the effect of DHEAS on other testosterone methods using a UK National External Quality Assessment Scheme (UK NEQAS) for steroid hormones special distribution.

Separate male and female matrix pools of normal human serum were prepared and divided into three portions. Two portions from each matrix were spiked with 10.07 and 20.14. micromol/L DHEAS, respectively. Aliquots of these pools were distributed to participants in UK NEQAS for male and female testosterone at distribution 319 (July 2006). Median testosterone results for each method group were examined for an increase in testosterone concentration.

In the female matrix, the effect on Abbott Architect was confirmed and shown also for Roche Elecsys, Roche E170 Modular and Beckman Access (includes some Beckman DxI users). In the male matrix, the effect on Abbott Architect, Roche Elecsys and Roche E170 Modular was similar in magnitude to that in the female matrix, but was smaller for Beckman Access/DxI. However, the effect on Immulite 2000 (includes some Immulite 2500 users) was greater in the male matrix. Indications of interference in other methods, used by only a few laboratories (notably Tosoh AIA and Wallac Delfia), were also observed.

DHEAS interference in testosterone assays is a feature of many routine testosterone methods, and occurs in both male and female matrices.