What You Need To Know About Secondary Hypertension: The Ultimate Guide

Hypertension is when you have high blood pressure. It is common in the United States, where about a third of the adult population has hypertension (116 million.)¹ Hypertension puts you at risk of heart disease or stroke, which are among the leading causes of death in the United States.

Types include primary and secondary hypertension. Primary hypertension accounts for 90-95% of all diagnosed cases. Secondary hypertension is not as prevalent as primary hypertension, accounting for 5-10%². Childhood secondary hypertension is usually hereditary, with 46%³ having a family member with the condition.

What is secondary hypertension?

Secondary hypertension is high blood pressure caused by another underlying condition affecting your kidneys, heart, arteries, or endocrine system. Because it’s a rare condition, the underlying causes aren’t always clear and may require more in-depth investigations to discover.

The prevalence and causes of secondary hypertension vary by age. It accounts for many hypertensive cases among children and young people. Causes include:

• Renal parenchymal disease in children 

• Renal artery stenosis caused by fibromuscular dysplasia in young women

• Renal failure and atherosclerotic renal artery stenosis in adults 65 or older

Secondary hypertension can occur during pregnancy. Most commonly, renovascular disease, Cushing’s syndrome, and pheochromocytoma cause secondary hypertension in pregnancy. This hypertension could develop further into preeclampsia.

Compared to preeclampsia from primary hypertension, preeclampsia caused by secondary hypertension has higher odds of adverse maternal and fetal outcomes.

Maternal risks include:

• Placental abruption (placenta detaches from the uterus before birth)

• Disseminated vascular coagulation (abnormal clotting in blood vessels)

• Multiple organ failure 

• Cardiovascular disease

Fetal risks include:

• Preterm birth

• Intrauterine growth restriction

• Intrauterine death

What are the common symptoms of secondary hypertension?

If you have secondary hypertension, you will generally exhibit symptoms similar to primary/essential hypertension.

Hypertension is asymptomatic in many cases. There are no definitive signs for secondary hypertension, so your physician will usually check several factors. These include resistant hypertension (high blood pressure that’s unresponsive to treatment) or hypertension that appeared suddenly at a young age without any family history.

As different conditions cause secondary hypertension, each one can present with symptoms. These symptoms appear in addition to possible hypertension symptoms. If your blood pressure is very high, symptoms include severe headache, nose bleed, fatigue, and shortness of breath.

Underlying conditions and their related symptoms include:

• Renal artery stenosis: Flash pulmonary edema (sudden build-up of liquid in the lungs)

• Pheochromocytoma: Palpitations, sweating, anxiety, frequent headaches 

• Obstructive sleep apnea: Daytime sleepiness, snoring

• Cushing’s syndrome: Weight gain, purple lines on your abdomen, loss of menstrual periods

• Hypokalemia/primary aldosteronism: Weakness, cramps, muscle twitches, arrhythmia

• Thyroid dysfunction: Tiredness, irregular gain or loss of weight, heat or cold intolerance

What is the most common cause of secondary hypertension?

The causes of secondary hypertension vary depending on age. Since secondary hypertension only happens when there is an underlying condition, it has many causes.

Here are some of the most common causes of secondary hypertension. 

Pheochromocytoma

Pheochromocytoma is a rare, typically benign tumor that develops in the adrenal glands. It can occur at any age, but it’s most prevalent in people between 30 and 50.

According to the National Cancer Institute, only eight people per one million have the condition, and about 25-35% of cases are inherited.

Symptoms of pheochromocytoma include:

• High blood pressure

• Fatigue 

• Headaches 

• Fast heart rate

• Weight loss  

• Shortness of breath

Cushing’s syndrome

Cushing's syndrome happens when the body produces too much cortisol, also known as the stress hormone. Cortisol maintains blood pressure, regulates glucose, reduces inflammation, and turns food into energy.

Your body can overproduce cortisol if you’re taking medicines similar to cortisol, such as glucocorticoids, which fight inflammation. It’s also possible an underlying condition like pituitary gland tumors or adrenal gland disease can cause cortisol overproduction.

Cushing's syndrome can lead to heart attack, stroke, high blood pressure, bone loss, infections, memory loss, and concentration problems. 

Symptoms vary, but you’re more likely to have clear symptoms if you have high cortisol levels. Below are some signs of Cushing's syndrome:

• Weak muscles

• Easy bruising

• Weight gain

• Thin legs and arms

• Purple stretch marks, primarily on the abdomen, breasts, hips, and under the arms

Renal parenchymal disease

Renal parenchymal disease damages the functional part of the kidney, the parenchyma. It’s the most common cause⁴ of secondary hypertension, accounting for 2.5% to 5% of all cases, mostly affecting children.

The causes of this condition are:

• Genetics (polycystic kidney)

• Hereditary from parents

• Autoimmune disease (lupus nephritis)

• Diabetes

• Infection

• Certain medications

• Interstitial kidney diseases (polycystic kidney disease and chronic pyelonephritis)

Common symptoms include:

• Presence of blood in the urine

• Bone changes

• Swelling of feet/hands/ eyes

• Feeling tired

• Anemia

• Persistent itchy skin 

Coarctation of the aorta

This heart condition is where the largest body’s artery tightens or constricts. As a result, the heart increases its contraction force to pump blood through the tightened artery, increasing blood pressure.

One type of aortic coarctation is complex and usually diagnosed in infancy. It presents with accompanying heart failure and other congenital abnormalities.

The other type is simple coarctation. Usually, it’s found in adults, and it’s not associated with other heart lesions. Aortic coarctation can be fatal if you don’t receive treatment.

In mild cases, you may be symptom-free until adulthood.

Symptoms include:

• Headache

• Shortness of breath

• Chest pain

• Exercise intolerance

• Nose bleeds

• Hard-to-control high blood pressure

• Cold feet or leg pain after exercising

Thyroid dysfunction

Thyroid dysfunction can cause secondary hypertension, mainly affecting adults. Both hypothyroidism and hyperthyroidism are causes of secondary hypertension. Thyroid hormones affect systemic vascular resistance and cardiac output.

Additionally, parathyroid gland dysfunction can also cause secondary hypertension.  Hyperparathyroidism can occur when the parathyroid gland releases too much parathyroid hormone. Consequently, the calcium in your body rises, triggering secondary hypertension.

Hyperthyroidism: Increased production of thyroid hormones.

Common signs include:

• Having trouble sleeping

• Weakness in muscles and tremors

• Loss of weight even with increased appetite

• Experiencing nervousness, anxiety, and irritability

• Having a goiter

• Excess sweating

Hypothyroidism: Decreased production of thyroid hormones.

Some symptoms include:

• Slow heart rate

• Swollen feet/eyes/ hands

• Less active than usual

• Being sensitive to cold

• Weight gain

Hyperparathyroidism: Overproduction of parathyroid hormone.

Symptoms include:

• Bone and joint pain

• Weight loss

• Loss of appetite

• Excessive urination

• Depression

Fibromuscular dysplasia

Fibromuscular dysplasia is a noninflammatory, nonatherosclerotic vascular disease that commonly involves the renal (kidney) and carotid arteries (in your neck). It affects women between 40 and 60 the most.

Fibromuscular dysplasia involving renal arteries often leads to secondary hypertension.

Unfortunately, fibromuscular dysplasia is not curable, but some medications can manage symptoms. A procedure called percutaneous transluminal angioplasty (PTA) can widen narrowed vessels. If a PTA procedure isn’t possible, revascularization surgery is another option.

Symptoms associated with the carotid arteries are:

• Headache

• Sudden neck pain

• Dizziness

• Pulsating ringing in your ears

Symptoms associated with renal artery damage are:

• High blood pressure

• Poor kidney function

Hyperaldosteronism

Hyperaldosteronism features elevated levels of aldosterone secretion by the adrenal glands. This leads to your kidneys retaining high levels of sodium and water, causing an increase in blood pressure. Hyperaldosteronism is the most common cause of drug-resistant hypertension.⁵

Symptoms include:

• Muscle weakness

• Muscle spasms

• Feeling tired all the time

• Frequent urination

• Extreme thirst

• Tingling

Obstructive sleep apnea

Obstructive sleep apnea is a condition where your breathing is frequently interrupted during sleep due to your throat muscles relaxing. They narrow or close your airway, blocking your breathing. This condition is common in men 40 to 59 years of age, particularly those who are obese.

Obstructive sleep apnea causes hypertension due to hypoxia (lack of oxygen) during sleep. This leads to blood vessel damage, increasing resistance, and causing diastolic and systolic blood pressure surges at night.

For most people, blood pressure remains elevated during the day when breathing is normal.

Fortunately, this condition is treatable. If you have any of these symptoms, speak with your doctor to find the best treatment for you.

Symptoms may include:

• Snoring

• Daytime sleepiness

• Morning or night-time hypertension

• Confusion

• Headaches

• Depression or irritability

What is the difference between primary and secondary hypertension?

Primary or essential hypertension is what most people mean when they say hypertension, and it’s much more prevalent than secondary hypertension. Essential hypertension is not caused by any known underlying condition, unlike secondary hypertension.

Primary hypertension risk factors include one or more of the following:

• Age 

• Genetics

• Lifestyle

• Diet, including salt consumption

• Weight

• Stress

• Excessive alcohol consumption 

• Smoking

The causes of secondary hypertension vary by age, whereas essential hypertension increases by age. Secondary hypertension is far more prevalent in children under 11. They account for 70-85% of all diagnosed secondary hypertension cases.

Another critical difference between the two is their treatment. When treating secondary hypertension, the physician has to address the underlying condition, managing secondary hypertension in the process.

You can treat primary hypertension with lifestyle changes and medication. However, if your hypertension resists these measures, often secondary hypertension is suspected. It indicates an underlying issue that stops your blood pressure from responding to regular treatments.

How is secondary hypertension diagnosed?

Early diagnosis of secondary hypertension and appropriate targeted treatment can potentially improve blood pressure. It can control or reduce the number of prescribed antihypertensive medications in some people or cure hypertension in others.

To start, your healthcare specialist will use an inflatable cuff to measure your blood pressure, just like in a routine appointment. However, even if you have high blood pressure, the doctor cannot diagnose hypertension during the first appointment. It usually takes between three and six high blood pressure readings on different occasions (at the doctor’s office or home) for the physician to diagnose hypertension.

Your doctor can only properly diagnose secondary hypertension through investigations to pinpoint the cause. Some additional tests include:

• Electrocardiogram (ECG or EKG): A painless, non-invasive test that records your heart's electrical signals. If your physician thinks a heart issue is the cause of secondary hypertension, they’ll recommend this test. During the ECG, the technician attaches electrodes (sensors) to your chest, which they connect to a computer. This records your heart's electrical signals as waves on paper or a monitor. 

• Blood test: Doctors order these tests to get a complete blood picture, including red and white blood cells count, hemoglobin levels, and platelets. Blood tests can also measure blood glucose, potassium, creatinine, sodium, total cholesterol, and triglycerides. 

• Kidney ultrasound: Kidney diseases are a common cause of secondary hypertension.

• Urine test: Your physician might collect a urine sample to look for indicators of an underlying condition causing your high blood pressure.  

• Sleep study to diagnose obstructive sleep apnea.

• T3, T4, TSH levels to investigate thyroid function.

• CT scans to diagnose aldosteronism or coarctation of the aorta.

• Magnetic resonance angiography (MRA) to diagnose renovascular disease.

Secondary hypertension treatment options

The key to treating secondary hypertension is treating the underlying medical condition. Once you receive treatment for the underlying condition, you may be able to manage your hypertension easily.

Treatment for secondary hypertension varies, and it may involve medications or surgery. If your case is complex, you may still need blood pressure medication and other medications for the underlying medical condition.

Your doctor may prescribe these medications:

Beta-blockers

Beta-blockers reduce your heart’s workload and open your blood vessels. They also lower your heart rate and make your pulse less powerful. Beta-blockers are not effective for some people when prescribed alone, but their efficacy increases when combined with thiazide diuretics.

Angiotensin-converting enzyme (ACE) inhibitors

These enzyme inhibitors relax your blood vessels and are crucial in treating secondary hypertension if you have kidney failure, coronary artery disease, or heart failure. 

Thiazide diuretics

Thiazide diuretics are also called water pills, and they help your kidneys remove excess sodium and water. It’s the primary diuretic for secondary hypertension, but it’s not the only available option. Diuretics tend to be generic and cheaper than other types of hypertension medication.

You may also take diuretics with ACE inhibitors and beta-blockers. Working together, they effectively treat your hypertension if it isn’t responsive to these treatments on their own.

Calcium channel blockers

Calcium channel blockers relax your blood vessel muscles or slow your heart rate. In some people, calcium channel blockers work better than angiotensin-converting enzymes or beta-blockers administered independently.

Calcium channel blockers interact with grapefruit juice, increasing the medication levels in your blood and putting you at a higher risk of side effects.

Direct renin inhibitors

Direct renin inhibitors medicines usually widen and relax your arteries by preventing the action of an enzyme (protein) known as renin. The kidney releases renin to regulate your blood pressure.

Part of the renin activation process is the creation of angiotensin, which narrows your blood pressure, and the production of aldosterone, which tells your kidneys to hold onto water and salt. These two hormones raise blood pressure, so blocking renin’s action prevents this chain reaction.

The lowdown

Secondary hypertension is less common, and its rarity makes it difficult to diagnose the condition without in-depth investigations. In some cases, your condition could become more severe before you receive a diagnosis.

Fortunately, since an underlying medical condition causes secondary hypertension, it is possible to treat. Early diagnosis is essential, so book an appointment with your healthcare provider if you suspect any conditions that cause secondary hypertension.