Total testosterone quantitative measurement in serum by LC-MS/MS

Measured dehydroepiandrosterone sulfate positively influences testosterone measurement in unextracted female serum: comparison of 2 immunoassays with testosterone measured by LC-MS.

Candidate Reference Measurement Procedure for the Quantification of Total Serum Cortisol with LC-MS/MS.

BACKGROUND Accurate measurement of serum cortisol is required to diagnose and treat adrenal disorders. Although certified reference materials (CRMs) are available to standardize cortisol measurements, External Quality Assessment (EQA) schemes still demonstrate a wide dispersion of results. We present a serum cortisol candidate reference measurement procedure that, through analysis of a Joint Co...

Comparison of 7 Published LC-MS/MS Methods for the Simultaneous Measurement of Testosterone, Androstenedione, and Dehydroepiandrosterone in Serum.

BACKGROUND Recently, LC-MS/MS was stated to be the method of choice to measure sex steroids. Because information on the mutual agreement of LC-MS/MS methods is scarce, we compared 7 published LC-MS/MS methods for the simultaneous measurement of testosterone, androstenedione, and dehydroepiandrosterone (DHEA). METHODS We used 7 published LC-MS/MS methods to analyze in duplicate 55 random sampl...

Serum total testosterone is lower in men with Alzheimer's disease.

OBJECTIVES The purpose of this study was to determine whether the level of serum total testosterone (TT) was different in cases of Dementia of the Alzheimer's Type (DAT) than in controls. SETTING AND DESIGN We included 83 referred DAT cases and 103 cognitively screened volunteers (aged 75+/-9 years) from the Oxford Project To Investigate Memory and Ageing. METHODS Information was obtained a...

The measurement of total serum proteins by the Biuret method.

The biuret reaction for proteins provides a simple and precise method for measuring serum proteins; Beer's law is obeyed to at least 10 g per dl. Several stable biuret reagents are available. Hemoglobin is the only important cause of interference which cannot be minimized by use of a sample blank. The mechanism of the biuret reaction is described and attention is drawn to the heterogeneity of t...