In most cases of high blood pressure (hypertension), there is no known cause. About 6% of the time, however, high blood pressure is caused by another condition or disease. When this happens, it is called secondary hypertension.
Most of the conditions that cause secondary hypertension involve the overproduction of one of the body's hormones. Some of the medical problems that can cause secondary hypertension include:
Kidney disease. Secondary hypertension can be related to damaged kidneys or to an abnormal narrowing of one or both renal arteries. The renal arteries are the major blood vessels that bring blood to each kidney. When the kidney's blood supply is reduced by a narrowing (called renal artery stenosis), the kidney produces high levels of a hormone called renin. High levels of renin trigger the production of other substances in the body that raise blood pressure, particularly a molecule called angiotensin II.
Adrenal disease. The adrenal glands sit on top of the kidneys and produce several hormones that help regulate blood pressure. Sometimes, one or both adrenal glands make and secrete an excess of one of these hormones.
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