Secondary high blood pressure (secondary hypertension) is high blood pressure that's caused by another medical condition. Secondary hypertension can be caused by conditions that affect your 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 referred to simply as high blood pressure.
Proper treatment of secondary hypertension can often control both the underlying condition and the high blood pressure, which reduces the risk of serious complications — including heart disease, kidney failure and stroke.
Like primary hypertension, secondary hypertension usually has no specific signs or symptoms, even if your blood pressure has reached dangerously high levels.
If you've been diagnosed with high blood pressure, having any of these signs may mean your 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 doctor how often to have your blood pressure checked.
Many different diseases and 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 your kidneys.
Renovascular hypertension is often caused by the same type of fatty plaques that can damage your 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 may 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 you to not get enough oxygen.
Not getting enough oxygen may damage the lining of the blood vessel walls, which may make it harder for your blood vessels to control your blood pressure. In addition, sleep apnea causes part of the nervous system to be overactive and release certain chemicals that increase blood pressure.
Obesity. As you gain weight, the amount of blood flowing through your body increases. This puts added pressure on your artery walls, increasing your blood pressure.
Being overweight also increases the heart rate and makes it harder for your 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.
Over-the-counter decongestants and certain 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 you have that's causing your high blood pressure. If you don't receive treatment, secondary hypertension can lead to other health problems, such as:
Metabolic syndrome. This syndrome is a cluster of disorders of your 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, your doctor will first take a blood pressure reading using an inflatable cuff, just as your blood pressure is measured during a typical doctor's appointment.
Your doctor may not diagnose secondary hypertension based on only one higher than normal blood pressure reading. It may take three to six high blood pressure measurements at separate appointments to diagnose secondary hypertension. These measurements may come from home blood pressure monitoring and ambulatory blood pressure monitoring. With ambulatory blood pressure monitoring, a device takes blood pressure measurements automatically at specific times throughout the day.
Your doctor will also want to do tests that check other markers to pinpoint the cause of your high blood pressure. These could include:
Electrocardiogram (ECG or EKG). This painless noninvasive test records the electrical signals in your heart. You might have this test if your doctor thinks a heart problem might be causing your secondary hypertension.
In this test, sensors (electrodes) are attached to your chest and sometimes to your limbs. Wires attach the electrodes to a computer. The computer records the heart's electrical signal information and displays it as waves on a monitor or on paper. This test can quickly reveal the timing and duration of each phase in your heartbeat.
Treatment for secondary hypertension involves treating the underlying medical condition with medications or surgery. Once the underlying condition is treated, your blood pressure might decrease or return to normal.
You may need to continue to take blood pressure medication as well, and any underlying medical condition you have may affect your doctor's choice of medication.
Possible drug choices include:
Thiazide diuretics. Diuretics, sometimes called water pills, are medications that help your 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 doctor about adding one or replacing a drug you currently take with a diuretic. Possible side effects of diuretics include weakness, leg cramps and a higher risk of sexual dysfunction.
Beta blockers. These medications reduce the workload on your heart and open your blood vessels, causing your 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. In addition, beta blockers generally aren't prescribed 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 — not the formation — 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 your blood vessels or slow your 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 your blood and putting you at a higher risk of side effects. Ask your doctor or pharmacist if your medication is affected by grapefruit juice.
Direct renin inhibitors. These medications relax and widen the arteries by prevention the action of a protein (enzyme) called renin. Renin is released by your kidneys and helps control blood pressure. An example of a direct renin inhibitor is as aliskiren (Tekturna).
Common side effects of aliskiren include dizziness and diarrhea. If you have diabetes or moderate to severe kidney problems, you shouldn't use aliskiren in combination with ACE inhibitors or angiotensin II receptor blockers.
Treatment for secondary hypertension can sometimes be complicated. You may need more than one medication combined with lifestyle changes to control your high blood pressure. Your doctor will want to see you more frequently — possibly as often as once a month — until your blood pressure is controlled. Your doctor may also recommend that you keep track of your blood pressure at home.
Healthy lifestyle changes are recommended to keep your heart healthy and your blood pressure low. These include:
Decreasing the salt in your 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.
While you can reduce the amount of salt you eat by putting down the saltshaker, you should also pay attention to the amount of salt that's in the processed foods you eat, such as canned soups or frozen dinners.
Your high blood pressure may be discovered during a routine physical. At that point, your primary care doctor may order more tests or refer you to a doctor who specializes in treating whatever the suspected underlying cause of your high blood pressure may be. For example, if your doctor 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).
Because appointments can be brief, and there's often a lot to cover, it's a good idea to arrive well prepared. Here's some information to help you get ready for your appointment and know what to expect from your doctor.
Your time with your doctor may be limited, so preparing a list of questions can help you make the most of your time together. For secondary hypertension, some basic questions to ask your doctor include:
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment.
Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your doctor may ask: