World Hypertension Day 2025: What is secondary hypertension? Know all about this high BP condition

Hypertension, commonly known as high blood pressure, is a major risk factor for cardiovascular diseases. It affects millions of people worldwide, and most cases of hypertension are classified as primary or essential with have no identifiable cause. However, some people also develop secondary hypertension. It’s cause is usually a health condition or a medication you are on. You may have headaches, but it is possible to show no signs at all. That’s why it is important to check your blood pressure regularly. On World Hypertension Day, observed on May 17, we tell you all about secondary hypertension.

What is secondary hypertension?

It is high blood pressure that arises as a direct consequence of an underlying, identifiable health condition. “It results from disorders that affect the heart, kidneys, blood vessels or endocrine system,” says cardiologist Dr Abhijit Borse. It is not common, as up to 10 percent of adults with hypertension have secondary hypertension, according to research published in StatPearls. Treating the root cause can often normalise blood pressure levels in people with this type of hypertension.

What are the causes of secondary hypertension?

Here are some of the reasons for this type of hypertension:

1. Kidney-related causes

• Renal Artery Stenosis is the narrowing of the kidney arteries that reduces blood flow to the kidneys. “In response, the kidneys interpret this as low blood pressure and activate the renin-angiotensin-aldosterone system, which is a hormone system that regulates blood pressure,” says the expert. This system narrows the blood vessels and promotes sodium and water retention, which increase blood volume and pressure.
• In the case of Chronic Kidney Disease (CKD), damaged kidneys struggle to excrete sodium and water, leading to fluid overload. “Also, CKD enhances sympathetic nervous system activity, which contributes to elevated blood pressure,” shares the expert.

2. Endocrine causes

• Primary Aldosteronism (Conn’s Syndrome) is a condition in which adrenal glands produce excess aldosterone, a hormone that promotes sodium retention and potassium excretion. The result is increased hypertension.
• Cushing’s Syndrome is a condition that occurs from exposure to high levels of cortisol, which is often due to tumors or steroid use. It occurs in less than 0.1 percent of people with hypertension, according to research published in The Medical clinics of North America.
• Pheochromocytoma is a rare adrenal tumor that secretes catecholamines (a group of neurotransmitters and hormones) that causes increased heart rate, and elevated cardiac output, leading to hypertension. Hyperthyroidism increases cardiac output while hypothyroidism increases systemic vascular resistance, which can cause hypertension.

3. Obstructive Sleep Apnea

It is a sleep disorder that leads to poor sleep quality, as breathing gets affected. So, it triggers sympathetic nervous system activation and increases levels of endothelin, which plays a role in regulating blood pressure. These changes cause persistent increases in blood pressure, especially during the night.

4. Medications

“Certain drugs such as NSAIDs (nonsteroidal anti-inflammatory drugs), oral contraceptives, steroids and decongestants can raise blood pressure,” says Dr Borse. They may promote sodium retention, and lead to high blood pressure.

5. Coarctation of the Aorta

This congenital narrowing of the aorta (large blood vessel) causes reduced perfusion to the lower body and increased resistance in the upper body. The kidneys see this as systemic hypotension (a drop in blood pressure) and respond by raising blood pressure.

What are the symptoms of secondary hypertension?

Many people remain asymptomatic, especially in early stages. When symptoms do occur, they may include:

• Headaches particularly in the morning
• Blurred vision or spots
• Shortness of breath if underlying cardiac or kidney disease is advanced
• Flushing or sweating
• Palpitations or chest pain
• Frequent nighttime urination may signal renal causes.

How to diagnose secondary hypertension?

A few tests are involved to find out if you have secondary hypertension:

• Assessment of age at onset (younger than 30 or sudden onset after age 55), hypertension despite multiple medications, and symptoms pointing to specific disorders.
• Blood and urine analyses to evaluate kidney function, electrolyte balance, cortisol levels and thyroid function.
• Renal ultrasound for kidney structure, adrenal imaging for tumors, and echocardiography for heart function.
• Polysomnography to diagnose obstructive sleep apnea.

What is the difference between primary and secondary hypertension?

Here are the key differences between primary and secondary hypertension:

• Prevalence: While secondary hypertension is rare, primary hypertension accounts for 95 percent of all cases of hypertension, according to research published in the Journal of the American Heart Association.
• Causes: In the case of primary hypertension, there is no specific identifiable cause. Secondary hypertension, on the other hand, is directly attributable to an underlying condition.
• Onset: Primary hypertension happens gradually, often in middle age. “But secondary hypertension can be sudden, any age depending on the cause,” says the expert.

How to treat secondary hypertension?

The treatment often revolves around the root cause.

1. Kidney-related treatment

• Renal Artery Stenosis: Angioplasty with Stenting Balloon dilatation is done followed by stent placement to restore renal perfusion (the flow of blood through the kidneys) and improve blood pressure.
• Chronic Kidney Disease: Sodium restriction and use of diuretics to reduce fluid overload.

2. Endocrine-related therapies

• Primary Aldosteronism: Surgical removal of an aldosterone-producing adenoma (tumor) can cure hypertension.
• Cushing’s Syndrome: Adrenal Surgery Resection of pituitary or adrenal tumors normalises cortisol levels.
• Pheochromocytoma: Surgical removal of the catecholamine-secreting tumor can help.
• Thyroid dysfunction: In hyperthyroidism, antithyroid medications (methimazole, propylthiouracil), can normalise blood pressure. “As for hypothyroidism, thyroid hormone replacement can improve blood pressure control,” says the expert.

3. Obstructive Sleep Apnea management

Continuous Positive Airway Pressure (CPAP) therapy during sleep alleviates airway obstruction. “It often lowers daytime blood pressure by 5 to 10 millimeters of mercury,” says Dr Borse.

4. Coarctation of the Aorta

Balloon angioplasty and stenting, a minimally invasive approach, can relieve or open the blocked or narrowed arteries. “The procedure can normalise upper-body blood pressures,” says the expert.

5. Medication-induced hypertension

Identifying and discontinuing or substituting medications such as nonsteroidal anti-inflammatory drugs and corticosteroids, often leads to prompt blood pressure reduction. They can also go for the lowest effective dose, but this should be done only after checking with a doctor.

Secondary hypertension is connected to one of your health conditions or the medicine you are taking. The symptoms are usually not there, so frequent blood pressure checks at home is a must.