Secondary High Blood Pressure

Topic Overview

Secondary high blood pressure is high blood pressure that is caused by another disease or condition. It can also be caused by certain medicines.

If your doctor thinks that you may have secondary high blood pressure, you may need tests to diagnose other health problems. Your doctor will also check the medicines that you take, because some medicines can cause high blood pressure as a side effect.

If your doctor can treat the cause of the high blood pressure, it might lower your blood pressure.

Secondary high blood pressure is not common. The risk of secondary high blood pressure is higher in children than in adults. In adults, it may cause high blood pressure in about 5 out of 100 people who have high blood pressure.^{footnote 1}

What causes secondary high blood pressure?

Causes of secondary high blood pressure include:

• Kidney disease, such as narrowing of the kidney arteries.
• Certain medicines, such as birth control pills, amphetamines, appetite suppressants, some antidepressants, steroids, and some nonsteroidal anti-inflammatory drugs (NSAIDs).
• Hormone related diseases, such as hyperthyroidism, hypothyroidism, or Cushing's disease.
• Sleep apnea.
• Drinking a lot of alcohol (such as more than three drinks a day).
• Narrowing of the aorta (coarctation).

Your doctor may suspect that you have secondary high blood pressure if:

• Your blood pressure has suddenly gone up since it was last checked.
• You are young and your blood pressure is 160/100 or higher.
• You have had many treatments and medicines for high blood pressure, but it is still 160/100 or higher.
• You have symptoms of health problems that may raise blood pressure.
• Your kidneys don't work as well as they should.

How is it treated?

Secondary high blood pressure is typically treated by treating the cause of the high blood pressure. Your treatment depends on what is causing your high blood pressure and whether the high blood pressure should be lowered as soon as possible to prevent problems.

If a health problem is the cause, this high blood pressure may return to normal when the other health problem is treated. But treating the condition that has caused your secondary high blood pressure will not always lower blood pressure back to a normal level. In this case, you may need to treat the high blood pressure too.

If a medicine is the cause, this high blood pressure may return to normal if the medicine is stopped or the dose is adjusted.

How do hormones affect blood pressure?

Hormones play a big role in controlling your blood pressure. They send messages controlling your heart's output of blood, the stiffness of your arteries, and changes in your blood volume. For example, your body releases certain hormones (such as adrenaline) when it is under stress and needs more blood and oxygen.

Secondary high blood pressure caused by hormone problems is rare.

Hormone problems that can cause secondary high blood pressure include:

• Hyperaldosteronism.
• Cushing's disease.
• Pheochromocytoma (a tumor).
• Excess growth hormone.
• Thyroid problems.

How do kidneys affect blood pressure?

Your kidneys are essential for blood pressure control. As blood passes through your kidneys, special cells "measure" blood pressure in the blood vessels leading to your kidneys (renal arteries) and adjust the amount of the hormone renin that they secrete. Renin controls the production of two other hormones, angiotensin and aldosterone. And these hormones control the width of your arteries and how much water and salt is moved out of the body. Both of these affect blood pressure.

If your renal arteries become narrowed from atherosclerosis (renal artery stenosis), less blood flows to the kidneys, which causes blood pressure to rise.