Renin is an enzyme produced in the kidney and plays a role in the pathogenesis of hypertension. It stimulates the mechanism which increase blood pressure. Renin is found in the juxtaglomerular region of the kidney. It increases blood pressure, by hydrolyzing (breaking down) angiotensinogen (secreted by the liver), into Angiotensin I. Angiotensin I, is converted into the most potent vasoactive peptide Angiotensin II, in the lung epithelium. It constructs the smooth muscles of the blood vessels going to the heart and this increases heart to work more vigorously, thus increasing the blood pressure. Angiotensin II, also acts on the adrenal glands to and releases aldosterone which stimulates the epithelial cells in the distal tubule of the kidneys to increase the reabsorbsion ot sodium. It also to increases blood pressure. This mechanism is called Renin-Angiotensin and Aldosteron system. Renin should not be confused with Rennin (Chymosin) an enzyme produced in stomach to coagulate milk.
Interpretation: Renin inhibitors are used to treat hypertension.This is usually decided after measurement of Plasma Renin Activity(PRA).PRA may also rise in certain tumors.Plasma Renin measurements may be compared to plasma Aldosterone concentrations as PAC/PRA ratio. High renin with normal aldosterone may show the sensitivity to salt. Low renin and high aldosterone may mean thet the adrenal glands are not working normally. If both are high it may show a problem with kidneys. Renin and aldosterone are the highest in the morning and they also give different results when the patient is sitting or lying down. Because, renin measurement is affected by the body position and diurnal variations. These details, should be noted by the laboratory or the doctor should order the test by mentioning these options.
Sample: Arm vein plasma (EDTA). Nonfasting.
Working day: Friday
Result Time: Next day 6:00 PM
