Learn more about high blood pressure that's caused by another medical condition. Find out about risk factors and treatments to help you stay healthy.
Secondary high blood pressure (secondary hypertension) is high blood pressure that's caused by another medical condition. It can be caused by conditions that affect the kidneys, arteries, heart or endocrine system. Secondary hypertension can also occur during pregnancy.
Secondary hypertension differs from the usual type of high blood pressure (primary hypertension or essential hypertension), which is often called simply high blood pressure.
Proper treatment of secondary hypertension can often control both the high blood pressure and the condition that causes it. Effective treatment reduces the risk of serious complications — including heart disease, kidney failure and stroke.
Like primary hypertension, secondary hypertension usually has no specific symptoms, even if blood pressure has reached dangerously high levels.
For people diagnosed with high blood pressure, having any of these signs may mean the condition is secondary hypertension:
If you have a condition that can cause secondary hypertension, you may need your blood pressure checked more frequently. Ask your health care provider how often to have your blood pressure checked.
Many health conditions can cause secondary hypertension. Several kidney diseases may cause secondary hypertension, including:
Renovascular hypertension. This type of high blood pressure is caused by narrowing (stenosis) of one or both arteries leading to the kidneys.
Renovascular hypertension is often caused by the same type of fatty plaques that can damage the coronary arteries (atherosclerosis) or a separate condition in which the muscle and fibrous tissues of the renal artery wall thicken and harden into rings (fibromuscular dysplasia).
Medical conditions affecting hormone levels also may cause secondary hypertension. These conditions include:
Other possible causes of secondary hypertension include:
Sleep apnea. In this condition, often marked by severe snoring, breathing repeatedly stops and starts during sleep, causing a lack of oxygen.
Not getting enough oxygen may damage the lining of the blood vessel walls, which may make it harder for the blood vessels to control blood pressure. Also, sleep apnea causes part of the nervous system to be overactive and release certain chemicals that increase blood pressure.
Obesity. As body weight increases, the amount of blood flowing through the body increases. This increase in blood flow puts added pressure on artery walls, increasing blood pressure.
Being overweight also increases the heart rate and makes it harder for the blood vessels to move blood. In addition, fat deposits can release chemicals that raise blood pressure.
Medications and supplements. Various prescription medications — such as pain relievers, birth control pills, antidepressants and drugs used after organ transplants — can cause or worsen high blood pressure in some people.
Some decongestants and herbal supplements, including ginseng, licorice and ephedra (ma-huang), may have the same effect. Many illegal drugs, such as cocaine and methamphetamine, also increase blood pressure.
The greatest risk factor for developing secondary hypertension is having a medical condition that can cause high blood pressure, such as kidney, artery, heart or endocrine system problems.
Secondary hypertension can worsen the underlying medical condition that's causing the high blood pressure. Without treatment, secondary hypertension can lead to other health problems, such as:
Metabolic syndrome. This syndrome is a cluster of disorders of the body's metabolism — including increased waist circumference, high triglycerides, low high-density lipoprotein (HDL) cholesterol (the "good" cholesterol), high blood pressure and high insulin levels.
If you have high blood pressure, you're more likely to have other components of metabolic syndrome. The more components you have, the greater your risk of developing diabetes, heart disease or stroke.
To diagnose secondary hypertension, a health care provider will take a blood pressure reading using an inflatable cuff.
A care provider might not diagnose secondary hypertension based on a single high blood pressure reading. It may take 3 to 6 high blood pressure measurements at separate appointments to diagnose secondary hypertension. Home blood pressure monitoring and ambulatory blood pressure monitoring might make up some of these readings. With ambulatory blood pressure monitoring, a device takes blood pressure measurements automatically at specific times throughout the day.
Other tests to help pinpoint the cause of the high blood pressure might include:
Electrocardiogram (ECG or EKG). This painless noninvasive test records the electrical signals in the heart. This test can help determine whether a heart problem might be causing secondary hypertension.
In this test, sensors (electrodes) are attached to the chest and sometimes to the limbs. The sensors connect to a computer that records the heart's electrical signal information and displays it as waves on a monitor or on paper. This test shows how the heart is beating.
Treatment for secondary hypertension involves treating the medical condition that's causing it with medications or surgery. Once the condition is treated, blood pressure might decrease or return to normal.
Treatment might require continuing to take blood pressure medication, as well. The underlying medical condition might affect this choice of medication.
Possible drug choices include:
Thiazide diuretics. Diuretics, sometimes called water pills, are medications that help kidneys eliminate sodium and water. Thiazide diuretics are often the first — but not the only — choice in high blood pressure medications.
Diuretics are often generic and tend to be less expensive than other high blood pressure medications. If you're not taking a diuretic and your blood pressure remains high, talk to your provider about adding one or replacing a drug you take with a diuretic. Possible side effects of diuretics include weakness, leg cramps and a higher risk of having sexual issues.
Beta blockers. These medications reduce the workload on the heart and open the blood vessels. This causes the heart to beat slower and with less force. When prescribed alone, beta blockers don't work as well in Black people — but they're effective when combined with a thiazide diuretic.
Possible side effects include fatigue, sleep problems, a slowed heart rate, and cold hands and feet. Beta blockers generally aren't used for people with asthma, as they can increase muscle spasms in the lungs.
Angiotensin-converting enzyme (ACE) inhibitors. These medications help relax blood vessels by blocking the formation of a natural chemical that narrows blood vessels. ACE inhibitors may be especially important in treating high blood pressure in people with coronary artery disease, heart failure or kidney failure.
Like beta blockers, ACE inhibitors don't work as well in Black people when prescribed alone, but they're effective when combined with a thiazide diuretic. Possible side effects include dizziness and coughing. ACE inhibitors should not be taken during pregnancy.
Angiotensin II receptor blockers. These medications help relax blood vessels by blocking the action of a natural chemical that narrows blood vessels. Like ACE inhibitors, angiotensin II receptor blockers often are useful for people with coronary artery disease, heart failure or kidney failure.
These medications have fewer potential side effects than do ACE inhibitors. Angiotensin II receptor blockers should not be used during pregnancy.
Calcium channel blockers. These medications help relax the muscles of the blood vessels or slow the heart rate. Calcium channel blockers may work better for some people than ACE inhibitors or beta blockers alone. Possible side effects include water retention, dizziness and constipation.
Grapefruit juice interacts with some calcium channel blockers, increasing levels of the medication in the blood and increasing the risk of side effects. Ask your health care provider or pharmacist if grapefruit juice affects your medication.
Direct renin inhibitors. These medications relax and widen the arteries by preventing the action of a protein (enzyme) called renin. An example of a direct renin inhibitor is as aliskiren (Tekturna).
Common side effects of aliskiren include dizziness and diarrhea. People with diabetes or moderate to severe kidney problems shouldn't use aliskiren in combination with ACE inhibitors or angiotensin II receptor blockers.
Treatment for secondary hypertension can sometimes be complicated. It might take more than one medication combined with lifestyle changes to control high blood pressure. Your health care provider will want to see you more often — possibly as often as once a month — until your blood pressure is controlled. Your provider may also recommend that you keep track of your blood pressure at home.
Healthy lifestyle changes are recommended to keep the heart healthy and blood pressure low. These include:
Decreasing salt in the diet. A lower sodium intake — 1,500 milligrams (mg) a day — is appropriate for people 51 years of age and older and for people of any age who are Black or who have hypertension, diabetes or chronic kidney disease. Otherwise healthy people can aim for 2,300 mg a day or less.
Reducing salt requires putting down the saltshaker and paying attention to the amount of salt in processed foods, such as canned soups or frozen dinners.
High blood pressure may be discovered during a routine physical. At that point, your primary care provider may order more tests or refer you to a provider who specializes in treating the suspected cause of your high blood pressure. For example, if your provider believes that a kidney problem is causing your high blood pressure, you'll likely be referred to a doctor who specializes in treating kidney disorders (nephrologist).
Here's some information to help you get ready for your appointment.
For secondary hypertension, some basic questions to ask include:
Don't hesitate to ask other questions.
Your provider is likely to ask you questions, including: