Plasma Renin Activity
Plasma renin activity (PRA) measures the action of renin, an enzyme released by the kidneys that starts a hormone cascade controlling blood pressure and fluid balance.
Renin kicks off the pathway that ultimately produces aldosterone and helps the body respond to changes in blood pressure, blood volume, and sodium. Measuring it helps clinicians understand what is driving blood pressure or electrolyte problems. Because renin responds to posture, salt, hydration, and many medications, sample timing and preparation matter a lot.
A high renin can reflect the body sensing low blood volume or low sodium, dehydration, certain medications, or narrowed kidney arteries. It is most informative when compared directly with aldosterone.
A low or suppressed renin, especially alongside a high aldosterone, can be a clue toward primary aldosteronism and is a reason for further evaluation.
Renin has no single ideal value; it is interpreted together with aldosterone and in light of your posture, salt intake, and medications at the time of testing. Your clinician will guide preparation and interpretation.
Sources
Educational context only, not medical advice or a diagnosis. Reference ranges vary by lab, age and sex; always discuss your results with a clinician.