Primary hypertension, or essential hypertension, is high blood pressure without an identifiable cause. Secondary hypertension refers to hypertension with a known underlying cause.
Approximately 30% of U.S. adults have hypertension. Primary hypertension may be more common than secondary hypertension. Around 5–10% of hypertension cases in adults are secondary hypertension.
However, 70–85% of cases in children up to age 12 are secondary hypertension.
According to the Centers for Disease Control and Prevention (CDC), hypertension does not usually cause symptoms or warning signs. Measuring your blood pressure will tell you your levels.
However, certain characteristics of high blood pressure may indicate secondary hypertension. These include:
- persistent high blood pressure that does not improve with medication
- increase in blood pressure with no previous high blood pressure episodes
- high blood pressure occurring in non-Black people younger than 30 years old and who do not have other risk factors for hypertension
- high blood pressure that occurs before puberty
- high blood pressure alongside other conditions, such as hypokalemia
- high blood pressure that remains high or does not lower at night
Learn more about how to monitor blood pressure.
Many conditions and factors are known causes of secondary hypertension.
More common causes of secondary hypertension include:
- diabetes mellitus
- obstructive sleep apnea
- obesity
- certain kidney conditions, such as:
- glomerulonephritis
- polycystic kidney disease
- renovascular disease
Other conditions, although less common, can also lead to secondary hypertension. These include:
- pregnancy
- hyperthyroidism or hypothyroidism
- Cushing’s disease
- congenital adrenal hyperplasia
- hyperaldosteronism
- lupus
- scleroderma
- coarctation of the aorta
- chronic kidney infections
- narrowing of the kidney’s arteries or other reno-vascular disease
- chronic kidney disease or failure
- certain drugs and medications
Drug-induced secondary hypertension
Taking certain substances may also lead to drug-induced secondary hypertension. These include medications and substances such as alcohol, for example:
- alcohol, nicotine, and other recreational drugs
- nonsteroidal anti-inflammatory drugs (NSAIDs)
- antacids containing sodium
- decongestants containing pseudoephedrine or phenylephrine
- some antidepressants, such as selective serotonin-noradrenaline reuptake inhibitors (SSNRIs)
- some appetite suppressants
- some medications used to treat attention deficit hyperactivity disorder (ADHD)
- some steroids, such as prednisone and methylprednisolone
- some immunosuppressants, such as cyclosporine
- some hormonal drugs, such as estrogens, androgens, and oral contraceptives
- some herbal supplements, such as St. John’s wort, ephedra, and liquorice
Risk factors for developing primary or secondary hypertension include:
- being over age 65
- having a family history of hypertension
- being of Black heritage
- having a high body mass index (BMI)
- eating too much salt and not enough fresh fruits and vegetables
- not getting enough exercise
- drinking high levels of alcohol or caffeine
- smoking
- having poor sleep quality
If you have a preexisting condition that can cause secondary hypertension, you’ll want to have your blood pressure checked more regularly.
Also, contact your doctor promptly if:
- You notice your blood pressure remains high despite taking your prescribed treatment.
- You find it difficult to take your prescribed treatment.
- You have other symptoms of illness.
- Your blood pressure levels improve and then increase again.
If you have measured your blood pressure and it’s 180/120 mm Hg or more, seek immediate medical care.
Read more about typical and high blood pressure readings.
A doctor may ask about your medical history, symptoms, and other health conditions to diagnose secondary hypertension. This also includes your family’s medical history.
Your doctor may perform a physical exam and take a blood pressure reading.
Other tests to find the cause of secondary hypertension include:
- a complete blood count or basic metabolic panel test
- urine analysis
- X-ray or CT scan, or other imaging scans
Treatment for secondary hypertension may include therapies that address the underlying causes and antihypertensive medication, lowering your blood pressure.
The medication may not make you feel any different, but that does not mean that it’s not effective.
Antihypertensive medications can include:
- beta-blockers
- angiotensin-converting enzyme (ace) inhibitors
- angiotensin receptor blockers
- thiazide diuretics
- calcium channel blockers
- direct renin inhibitors
Other treatment may be needed if high blood pressure has caused additional symptoms or damage due to complications.
Also, lifestyle changes may help your blood pressure stay in a healthy range and avoid complications. These can include:
- limiting your salt intake to less than 0.2 ounces a day
- eating a balanced diet with enough fresh fruit and vegetables
- limiting alcohol and caffeine intake
- exercising regularly
- maintaining a moderate weight
- avoiding or quitting smoking if you smoke
Without treatment, secondary hypertension can lead to other damaging health complications, including:
- heart disease and heart failure
- stroke
- peripheral artery disease
- vision impairment or damage
- metabolic syndrome
- kidney failure
You can protect yourself against the risk of complications by taking your medication and following your treatment plan as prescribed. It’s also important to have your blood pressure regularly tested to monitor increases.
Read more about the complications of hypertension.
With effective treatment, the outlook for secondary hypertension is positive. Treatment of the underlying cause can help to decrease blood pressure or even return it within a standard range.
Is secondary hypertension curable?
In some cases, treatment may address the cause of secondary hypertension and return blood pressure to a standard range. This may mean that for some people, secondary hypertension is curable.
If your blood pressure has remained stable within a healthy range for some years, your doctor may recommend reducing your treatment or stopping it altogether. However, some people may need to continue to take medication or follow other lifestyle approaches for their whole life.
Secondary hypertension occurs due to a known disease or condition that elevates blood pressure. By contrast, primary hypertension is when the cause is unknown. Secondary hypertension often causes no distinctive symptoms and is detectable by measuring blood pressure.
Once doctors identify the underlying cause, treatment may lead to lower blood pressure. Without effective treatment, secondary hypertension can lead to further health complications. Contact your doctor if you have concerns about secondary hypertension or believe your current treatment is not working.
