title: Low serum testosterone assayed by liquid chromatography-tandem mass spectrometry. Comparison with five immunoassay techniques.
abstract: 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.
authors: Department of Biochemistry and Genetics, University Hospital, F-49033 Angers, France. vamoal@chu-angers.fr
authors: Valérie
authors: V
authors: Moal
authors: Elisabeth
authors: E
authors: Mathieu
authors: Pascal
authors: P
authors: Reynier
authors: Yves
authors: Y
authors: Malthièry
authors: Yves
authors: Y
authors: Gallois
mesh_terms: 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*
chemical_list: D013739:Testosterone