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Clin Chem. 2008 Nov;54(11):1855-63. doi: 10.1373/clinchem.2008.103846. Epub 2008 Sep 18.

Simultaneous measurement of serum testosterone and dihydrotestosterone by liquid chromatography-tandem mass spectrometry.

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1
General Clinical Research Center, Division of Endocrinology and Metabolism, Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute, Torrance, CA 90509, USA.

Abstract

BACKGROUND:

Recent reports have described inherent problems with androgen immunoassays compared with mass spectrometry analyses.

METHODS:

We developed a method for measuring serum testosterone (T) and 5alpha-dihydrotestosterone (DHT) simultaneously via liquid-liquid extraction followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with positive-mode electrospray ionization.

RESULTS:

The DHT and T calibrators showed a linear response from 0.069 nmol/L to 34.4 nmol/L and 69.3 nmol/L, respectively. T interference in the DHT assay and vice versa were negligible. Within- and between-run imprecision values were <5% for both analytes. Percent recoveries of T and DHT spiked into samples at concentrations spanning the calibration curve were 100%-113% and 98%-107%, respectively. The lower limit of quantification was 0.069 nmol/L for both steroids. Serum T concentrations measured by LC-MS/MS were different from those obtained by RIA, especially at lower T concentrations. Serum DHT concentrations measured by LC-MS/MS were markedly lower than those generated by RIA because of the nonselectivity of the RIA without chromatography. The reference intervals (mean +/- 2 SDs) determined for T and DHT were 9.2-33.7 nmol/L and 0.47-2.65 nmol/L, respectively, for 113 healthy adult men and 0.33-2.02 nmol/L and 0.09-0.91 nmol/L, respectively, for 133 healthy premenopausal women.

CONCLUSIONS:

We have developed and validated a selective and precise method for simultaneous measurements of serum T and DHT that can be adopted for routine measurements of these androgens in health and disease in men and women.

PMID:
18801940
DOI:
10.1373/clinchem.2008.103846
[Indexed for MEDLINE]
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