- RENIN ACTIVITY
- Start Date
- Expiration Date
- Renin Activity
- CPT Codes
- Reference Test
- Transport Info
Centrifuge and immediately transfer plasma to separate plastic tube
CRITICAL FROZEN – Separate specimens must be submitted when multiple tests are ordered
- Fasting Required?
- Patient Instructions
Supine specimen: Draw before patient arises in morning
Upright specimen: Draw from patient who has been upright at least 2 hours
- Reference Range
Quantitative Radioimmunoassay (RIA)
Renin is released from the juxtaglomerular cells of the kidney. The enzyme acts in general circulation to cleave its substrate, an alpha-2 globulin synthesized by the liver, to produce the deca-peptide angiotensin I.
Angiotensin I is cleaved rapidly by the activity of converting enzyme, primarily in the lungs, to the biologically active octapeptide angiotensin II. In turn, angiotensin II is degraded rapidly to inactive peptide fragments by enzymes present in plasma and tissues, know as angiotensinases.
Angiotensin II has an extremely short in vivo half-life, but it is the most potent vasopressor known. Angiotensin II plays a key role in several forms of hypertension, as well as in blood pressure regulation. In addition, angiotensin II has been established as the major influence on aldosterone secretion by the adrenal gland.
Technical difficulties associated with the measurement of angiotensin II levels in blood have retarded general acceptance of its assay in the clinical laboratory. Since angiotensin I levels are a direct representation of plasma renin activity, the determination of plasma renin activity has been adopted widely to evaluate the renin-angiotensin system in disease states. Measurement of plasma renin activity in hypertensives is an important aid in the differential diagnosis of primary and secondary aldosteronism. Estimation of renin activity is also valuable in determining the prognosis and most appropriate therapy for people with essential hypertension.