Plasma Renin Activity Unit Converter

Plasma renin activity (PRA) measures how quickly the enzyme renin generates angiotensin I in a blood sample over a set time period. It is reported in nanograms per milliliter per hour (ng/mL/hr).

Renin is an enzyme produced by the kidneys that initiates the renin-angiotensin-aldosterone system (RAAS), a hormonal cascade that regulates blood pressure, fluid balance, and electrolyte levels. When blood pressure or sodium levels drop, the kidneys release renin, which converts angiotensinogen into angiotensin I. This is then converted to angiotensin II, a potent vasoconstrictor that also stimulates aldosterone release.

PRA reflects the functional activity of renin and is commonly measured alongside aldosterone to calculate the aldosterone-to-renin ratio, a key screening tool for conditions like primary aldosteronism.

Renin is produced and stored by juxtaglomerular cells in the walls of the afferent arterioles of the kidneys. These specialized cells release renin into the bloodstream in response to low blood pressure, reduced sodium delivery to the distal tubule, or sympathetic nervous system activation.