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:
- Kidney disease: 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.
- Adrenal disease: 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)
- Hyperparathyroidism: 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.
- Thyroid problems: 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