The connection between renin and blood pressure is that the production of renin causes blood pressure to rise. Renin is an enzyme produced by the kidneys. It is a key component of the renin-angiotensin system, a series of processes that raises blood pressure in abnormal situations. The body, for many reasons, can produce too much renin that leads to a state of maintained high blood pressure. This disorder is known as hypertension.
One of the main functions of the kidneys is to maintain proper blood pressure through reabsorbing water and electrolytes, or expelling them as urine. This process is gradual and, in a healthy body at rest, works normally. Yet, if one or a combination of three events occurs, the kidneys need assistance in raising blood pressure quickly. The three triggers are a sudden decrease in blood pressure, a fight or flight response created by the body's nervous system, and a lack of electrolytes in the blood.
When the kidneys detect one or more of these events, special cells within the kidneys release renin into the bloodstream. The release of renin is the first part of the renin-angiotensin system. Renin has many immediate but short-term effects on the body: increased thirst, decreased urination, constricted capillaries and a faster heart rate. Working together, these changes rapidly increase blood pressure. In this situation, higher renin and blood pressure levels always accompany one another.
In healthy adults, high renin and elevated blood pressure levels will only persist for a short time. Yet under certain conditions, the body continually produces renin. The consistent high blood pressure is a condition known as hypertension; if left untreated, hypertension can cause hardening of the arteries, heart attack and stroke. For roughly 95% of those with hypertension, there is no direct cause. Most physicians agree, though, that a series of lifestyle factors such as stress, diet, smoking and obesity all have an effect on increased renin production.
Though changing lifestyle factors can have a positive effect on hypertension, the link between renin and blood pressure has led to the development of drugs that inhibit the production of renin and thus lower blood pressure. This medication, though, is a temporary solution meant to halt the detrimental effects of hypertension. After a patient begins to take the drug, a physician or other health professional will work with the patient to eliminate the lifestyle factors that caused the overproduction of renin. This way the patient will be able to eventually stop taking medication and have a better quality of life. Though patients will never be able to eliminate the biological connection between high renin and blood pressure levels, they can make changes to their daily lives that will improve their overall health.