Renin Activity
Sample: Frozen EDTA plasma. See instructions. Special patient preparation is necessary before sampling
Schedule: Friday every two weeks
Units: ng/mL/hr
Range: 0.2 2.8 (At rest)
1.5 - 5.7 (In motion)
Critical value: Ratio plasma aldosterone/renin > 50 is critical
Remarks: Renin is a proteolytic enzyme that is produced by the juxtaglomerular cells of the kidney. In the circulation, renin acts to cleave renin substrate angiotensinogen to produce the inactive decapeptide Angiotensin I. This inactive Angiotensin I is cleaved by Angiotensin Converting Enzyme (ACE) to form the biologically active octopeptide, Angiotensin II. Angiotensin II is an extremely potent vasopressor that plays a decisive role in blood pressure regulation. Angiotensin II also stimulates the release of Aldosterone by the adrenal gland. Renin activity is used for the differential diagnosis of patients with hypertension: High Renin levels are found patients with hypertension due to renal artery stenosis. Renin activity also is used in the diagnosis of primary aldosteronism since patients with secondary aldosteronism usually have low Renin levels. In patients with adrenal insufficiency Renin activity is used to assess the adequacy of steroid substitution: Renin activity is normal in patients with adequate supplementation and increased in cases of inadequate steroid substitution.
