What is secondary hypertension?
Secondary hypertension happens when you have high blood pressure that is caused by a known disease or condition. High blood pressure, also called hypertension, is a common condition that is characterized by having a higher amount of pressure in your blood vessels than normal.
Blood pressure is typically measured with an inflatable cuff that is placed around your arm. When taking your blood pressure, your healthcare provider is looking for two measurements:
- Systolic blood pressure: Blood vessel pressure during a heart beat
- Diastolic blood pressure: Blood vessel pressure between heart beats
The two measurements are listed together, systolic on top of diastolic. A normal blood pressure measurement is less than 120/80. Once your blood pressure rises above this measurement, your healthcare provider will start to monitor you for high blood pressure. It’s a condition that can be treated.
High blood pressure that doesn’t have a known cause is called essential or primary hypertension. In contrast, secondary hypertension has a known cause.
How common is secondary hypertension?
Because secondary hypertension is rare, occurring in only 5 to 10 percent of the population, it is not always discovered. Testing for secondary hypertension can be expensive, so your healthcare provider will typically wait to begin testing until they strongly suspect secondary hypertension.
What causes secondary hypertension?
Secondary hypertension is high blood pressure that is caused by another condition or disease. There are many different conditions or diseases that can cause secondary hypertension, including:
An injury to the kidney or arteries that are too narrow can lead to poor blood supply to the organ. This can trigger higher production of a hormone called renin. Renin leads to production of substances in the body (like the protein molecule angiotensin II) that can raise blood pressure.
Located on top of the kidneys, the adrenal glands produce and regulate hormones. When there is a problem with these glands, hormones in the body can become unbalanced and cause several conditions. These conditions can include:
- Pheochromocytoma (a tumor of the adrenal gland that overproduces epinephrine and norepinephrine—the fight or flight hormones)
- Conn’s syndrome or primary aldosteronism (a condition where the body makes too much of the salt-retaining hormone aldosterone)
- Cushing’s syndrome (a condition where there is too much of the hormone cortisol, a regulator of carbohydrate metabolism and blood pressure)
In this condition, the parathyroid glands (located in the neck), overproduce hormones that regulate calcium levels in the blood, and this condition may lead to high blood pressure.
Abnormal thyroid function may also lead to high blood pressure.
Coarctation (constriction or tightening) of the aorta
This condition involves tightening of the aorta (the main artery on the left side of the heart). Coarctation restricts normal blood flow.
Obstructive sleep apnea
In this condition, a person is awakened frequently from sleep and has pauses in breathing during sleep due to collapsed passages in the upper airways.
Side effects from certain medications can also contribute to secondary hypertension. Medications like:
- Hormonal contraceptives (birth control pills)
- Non-steroidal anti-inflammatory agents (NSAIDs)
- Diet pills
- Immune system suppressants
What are the symptoms of secondary hypertension?
Symptoms of secondary hypertension can vary depending on the type of condition or disease that is acting in combination with high blood pressure. Additionally, there may be difficulty controlling high blood pressure by using just one or two medications. The American Heart Association guidelines now define high blood pressure as blood pressure reading 130/80 or higher.
Examples of symptoms for some conditions can include:
- Pheochromocytoma: Sweating, increased frequency or force of heartbeats, headache, anxiety
- Cushing’s syndrome: Weight gain, weakness, abnormal growth of body hair or loss of menstrual periods (in women), purple striations (lines) on the skin of the abdomen
- Thyroid problems: Fatigue (tiredness), weight gain or weight loss, intolerance to heat or cold
- Conn’s syndrome or primary aldosteronism: Weakness due to low levels of potassium in the body
- Obstructive sleep apnea: excessive fatigue or sleepiness during daytime, snoring, pauses in breathing during sleep
Who is tested for secondary hypertension?
Because secondary hypertension is relatively rare, and screening for causes can be expensive and time-consuming, not every patient with high blood pressure will be tested for the condition. Your healthcare provider will test you if they feel there is a strong probable case. There are several factors that help determine if you should be screened for secondary hypertension. These factors include:
- Age: Patients under 30 years who have high blood pressure with no family history or other risk factors of high blood pressure
- Resistant hypertension: Patients who have resistant hypertension have high blood pressure that has not improved despite optimal treatment with at least three blood pressure medications
- Obesity: Overweight patients with high blood pressure that does not respond to treatment over time
- Signs or symptoms suggestive of an underlying condition
- Laboratory abnormalities such as low potassium or high calcium
What tests will my healthcare provider do to diagnose secondary hypertension?
Your healthcare provider will focus on the symptoms and signs of conditions that could cause secondary hypertension. Physical signs could include:
- Change in body weight
- Fluid buildup (swelling)
- Abnormal hair growth
- Stretch marks on the skin of the abdomen
- Abnormal blood flow to the kidneys
Blood tests may also be done. These could include:
- Creatinine and blood urea nitrogen (BUN) tests to examine kidney function
- Calcium and potassium levels in the blood
- Thyroid function tests
Imaging tests could also be done to look at the size and structure of organs. These tests may include:
- An ultrasound of the kidneys to check their size and blood flow
- A contrast tomography (CT) scan or magnetic resonance imaging (MRI) to check the adrenal glands, or an arteriogram to track blood flow to the kidneys
Your blood pressure will also be monitored to see if it dips at different points in the day or night.
How is secondary hypertension treated?
Treatment for secondary hypertension will depend on the secondary condition your healthcare provider diagnoses. Secondary hypertension will last as long as you have the secondary condition. It is best to follow several tips for controlling high blood pressure (hypertension) while being treated for your underlying condition. These tips include:
- Eating a healthy diet that is low in sodium
- Exercising regularly
- Avoiding smoking
- Maintaining a healthy body weight
- Limiting alcohol
In cases where a tumor is found to be the cause of the secondary hypertension, surgery may be needed to treat the condition. For hormonal imbalances and other conditions, medication may be used to treat secondary hypertension.
Can secondary hypertension be prevented?
Some causes of secondary hypertension, such as tumors or abnormal blood vessel structures, cannot be prevented. Other causes of the condition, such as medication use or a high body weight, could be prevented through lifestyle changes and awareness of potential side effects of medications. Discuss medication side effects with your doctor. You should not stop any medications without a speaking to your doctor.
What is the outlook for those with secondary hypertension?
Secondary hypertension has a positive outlook with treatment. Early detection and treatment can help minimize the possibility of serious damage due to abnormal blood vessel shape or tumors.
Hypertension (high blood pressure) can become more common as patients age. It is not uncommon for patients to need to be continuously treated for high blood pressure, even after the underlying condition of their secondary hypertension has been treated.