Determination of urinary aldosterone using a plasma aldosterone 2D ID LC-MS/MS method.

Aim: In the diagnosis for primary aldosteronism, the measurement of urinary aldosterone is part of the confirmation test but diagnostic accuracy may be blunted due to poor immunoassay performance for urinary aldosterone. Nowadays, plasma aldosterone concentrations are measured preferably by LC-MS/MS yet such methods for urinary aldosterone are lacking.

Methods & Results: We show that plasma and urinary aldosterone can be measured with the same 2D isotope dilution LC-MS/MS method.