Low serum testosterone assayed by liquid chromatography-tandem mass spectrometry. Comparison with five immunoassay techniques.
BACKGROUND
Low levels of serum testosterone, as typically found in women and children, cannot be measured reliably by immunoassays. Our aim was to develop a sensitive assay to quantitate low serum testosterone concentrations using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results were compared to those obtained with various immunoassay techniques.


METHODS
Serum testosterone levels in 70 women and children were measured using LC-MS/MS and compared with two automated, non-isotopic immunoassays, and three manual, isotopic immunoassays. Serum extraction was required only for LC-MS/MS and one of the isotopic methods.


RESULTS
Deming regression analysis was used for comparison: the correlation coefficients were between 0.772 and 0.870, and the slopes between 0.972 and 1.365. Using Bland and Altman analysis, all the 5 immunoassays showed a positive mean difference compared with LC-MS/MS: all overestimated the testosterone levels in women and children.


CONCLUSIONS
None of the immunoassays tested proved sufficiently reliable when low testosterone concentrations (< or =3.47 nmol/L) were measured. In contrast to conventional isotopic and non-isotopic immunoassay techniques, LC-MS/MS allows the precise determination of low testosterone levels. It has adequate sensitivity and is not subject to interference from other steroids that were tested.
Moal
Valérie
V
Department of Biochemistry and Genetics, University Hospital, F-49033 Angers, France. vamoal@chu-angers.fr
Mathieu
Elisabeth
E
Reynier
Pascal
P
Malthièry
Yves
Y
Gallois
Yves
Y
D001322:Autoanalysis / Q000379:methods / Q000592:standards; D002648:Child; D002853:Chromatography, Liquid / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods* / Q000592:standards; D007553:Isotope Labeling; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods* / Q000592:standards; D013739:Testosterone / Q000097:blood*
D013739:Testosterone