The Renin, PRA & Hypertension App uses plasma renin activity (PRA) testing to guide antihypertensive drug selection with the goal of effective blood pressure control with as few agents as possible. It is based on the concept that hypertension is sustained by an excess of either body sodium-volume (V) or plasma renin (R), and that all antihypertensive drugs are either anti-V or anti-R.

A low PRA indicates V hypertension, treatment with an anti-V drug, and (if no compelling indications) subtraction of anti-R drugs. A medium to high PRA indicates R hypertension, treatment with an anti-R drug and then, if renin is blocked and BP not controlled, adding an anti-V drug.