Testosterone measured by 10 immunoassays and by isotope-dilution gas chromatography-mass spectrometry in sera from 116 men, women, and children.
BACKGROUND
Commercially available testosterone immunoassays give divergent results, especially at the low concentrations seen in women. We compared immunoassays and a nonimmunochemical method that could quantify low testosterone concentrations.


METHODS
We measured serum testosterone in 50 men, 55 women, and 11 children with use of eight nonisotopic immunoassays, two isotopic immunoassays, and isotope-dilution gas chromatography-mass spectrometry (ID/GC-MS).


RESULTS
Compared with ID/GC-MS, 7 of the 10 immunoassays tested overestimated testosterone concentrations in samples from women; mean immunoassay results were 46% above those obtained by ID/GC-MS. The immunoassays underestimated testosterone concentrations in samples from men, giving mean results 12% below those obtained by ID/GC-MS. In women, at concentrations of 0.6-7.2 nmol/L, 3 of the 10 immunoassays gave positive mean differences >2.0 nmol/L (range, -0.7 to 3.3 nmol/L) compared with ID/GC-MS; in men at concentrations of 8.2-58 nmol/L, 3 of the 10 immunoassays tested gave mean differences >4.0 nmol/L (range, -4.8 to 2.6 nmol/L).


CONCLUSIONS
None of the immunoassays tested was sufficiently reliable for the investigation of sera from children and women, in whom very low (0.17 nmol/L) and low (<1.7 nmol/L) testosterone concentrations are expected.
Taieb
Joëlle
J
Hormonology Laboratory, A. Béclère Hospital, 92141 Clamart, France.
Mathian
Bruno
B
Millot
Françoise
F
Patricot
Marie-Claude
MC
Mathieu
Elisabeth
E
Queyrel
Nicole
N
Lacroix
Isabelle
I
Somma-Delpero
Claude
C
Boudou
Philippe
P
D000328:Adult; D000368:Aged; D001322:Autoanalysis / Q000379:methods; D002648:Child; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008297:Male; D008875:Middle Aged; D011865:Radioisotope Dilution Technique; D013739:Testosterone / Q000097:blood*
D013739:Testosterone