Renin is an enzyme produced by the kidneys that helps control blood pressure. Renin works by activating other chemicals to narrow (constrict) blood vessels, which increases blood pressure; a decrease in renin levels helps lower blood pressure.
Normally, this mechanism keeps blood pressure within a healthy range. But some people develop chronic high blood pressure (hypertension). When this occurs, medicines may be used that block the action of renin on blood vessels.
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