Current hypertension guidelines stipulate that all incompatible medications be stopped before performing laboratory screening for aldosteronism, but patient adherence is unclear. We measured plasma drug concentrations to determine drug adherence and potential drug bias during biochemical tests. Plasma concentrations of 10 antihypertensive drugs were quantified by mass spectrometry in 24 consecutive ambulatory patients with uncontrolled hypertension routinely evaluated for aldosteronism. Drug screening was done before (first visit), and on the day of biochemical tests (second visit) after stopping all incompatible medications. Concentrations above those expected at trough dosing interval defined same-day dose intake. Nonadherence was frequent during laboratory evaluations for aldosteronism advocating cautious interpretation of results. A multicenter study is desirable to set the stage for new screening protocols that should incorporate also incentives and checks of drug adherence.
