Helping control blood pressure

One of the important functions of the kidneys is to regulate blood pressure.

Healthy kidneys make hormones such as renin and angiotensin. These hormones regulate how much sodium (salt) and fluid the body keeps, and how well the blood vessels can expand and contract. This, in turn, helps control blood pressure.

They do this by regulating:

• The amount of water in the body. If there is too much water in the body (fluid overload) blood pressure will go up. If there is too little water in the body (dehydration) the blood pressure will drop.
• The width of the arteries. The arteries constantly change in width as blood flows through them. The narrower the arteries, the higher the blood pressure. Renin helps control narrowing of the arteries. Failing kidneys often make too much renin. This raises blood pressure. If your blood pressure is high, your heart is working harder than normal to pump blood through your body.

High blood pressure (also called hypertension) caused by a breakdown in these functions is common in people with kidney failure. It is also a complication, a secondary condition caused by kidney failure.

May 1, 2006