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What Causes High Diastolic Blood Pressure?

Key Takeaways

  • Possible causes and risk factors of high diastolic blood pressure include obstructive sleep apnea (OSA), endocrine disorders such as hypothyroidism (low thyroid hormone levels), renal hypertension, and diabetes.

  • Diastolic hypertension is more often found in young adult males with previous cardiovascular events and a family history of hypertension. 

  • Isolated diastolic hypertension (IDH) may be higher in people with risk factors like  high blood sugar levels, chronic kidney disease, and a family history of hypertension. 

Hypertension (high blood pressure) is called a silent killer. It can cause severe damage in many organs without warning signs and is a particularly strong risk factor for heart disease and stroke. 

You may have noticed that blood pressure is expressed in two numbers, for example, 120/80 mmHg (millimeters of mercury). The first number (the top number on a blood pressure monitor) refers to systolic blood pressure (SBP), and the second number (bottom number) is the diastolic blood pressure (DBP). Please continue reading to find out what causes high diastolic blood pressure.

What is blood pressure?

Blood pressure is the force of blood pushing against the artery walls when the heart muscle pumps blood. The body regulates blood pressure through the brain’s blood pressure center. The body’s natural sodium balance also plays a role in blood pressure control. 

Intense exercise can temporarily raise blood pressure. Taking illegal drugs or certain medications, for example, common painkillers called nonsteroidal anti-inflammatory drugs (ibuprofen, naproxen), can also cause elevated blood pressure. 

When blood pressure levels remain consistently high, it is called hypertension or high blood pressure. Hypertension is a condition in which the blood flows through the arteries at a higher-than-normal pressure for a prolonged period of time. A healthy weight and regular physical activity can lower the risk of developing hypertension (high blood pressure). 

What do blood pressure numbers mean?

Blood pressure measurements are done with a blood pressure cuff that is usually placed on an arm. It is measured in millimeters of mercury (mm Hg or mmHg) and expressed as two numbers:

Systolic blood pressure (SBP)

The top, upper, or first number is the systolic blood pressure. It is the pressure in the blood vessels when your heart contracts or beats. 

Diastolic blood pressure (DBP)

The bottom, lower, or second number is the diastolic blood pressure. It is the pressure in the arteries when your heart relaxes between beats. 

Is 90 mmHg considered a high diastolic blood pressure?

A reading of 90 mmHg for diastolic blood pressure is considered high blood pressure or hypertension if the systolic blood pressure (the top number) is also high. 

Normal blood pressure is 120/80 mmHg or lower. Readings between 120/80 mmHg and 129/89 mmHg are considered pre-hypertension. 

A blood pressure reading of 130/80 mmHg or above is considered high and is labeled stage 1 hypertension. 

A reading of 140/90 mmHg or higher is called stage 2 hypertension. 

If you notice blood pressure readings of 180/110 mmHg or higher more than once a week, you should seek immediate medical attention (this is severe hypertension and is called a hypertensive crisis).

If the systolic blood pressure is normal, and the diastolic blood pressure has a reading of 90 mmHg, it is classified as isolated diastolic hypertension (IDH) or high diastolic blood pressure. 

Why is my diastolic reading high, but the systolic number is normal?

In a small number of people, high diastolic blood pressure occurs with normal systolic blood pressure. The cause often remains unknown. When either systolic or diastolic blood pressure or both numbers are high without a known cause, it is called primary hypertension or essential hypertension. 

Risk factors of isolated diastolic hypertension (systolic blood pressure below 140 mm Hg and diastolic blood pressure above 90 mm Hg) are linked to a higher body mass index (BMI), high blood sugar levels, and kidney disease. Other risk factors include having a family history of hypertension (high blood pressure) and having the male sex assigned at birth. 

It is also possible to have isolated systolic hypertension (elevated systolic blood pressure with normal diastolic blood pressure). Again, the cause is usually unclear. 

Elevated blood pressure (both systolic and diastolic hypertension) is the most common type. The causes are well known and include being overweight or obese, eating a high-salt diet, not getting enough exercise, smoking, drinking alcohol, mental stress, age above 65 years, and a family history of hypertension.

What is the most common cause of high diastolic blood pressure?

Possible causes of high diastolic blood pressure include obstructive sleep apnea and renal hypertension. Adults with endocrine disorders such as hypothyroidism (low thyroid hormone levels) and diabetes are also at a higher risk. Obesity and alcohol consumption are also potential causes of high diastolic blood pressure. 

Certain risk factors can raise the chances of developing diastolic hypertension, such as being 50 years old or younger, being assigned male at birth, having previous cardiovascular events, chronic kidney disease, and having a family history of hypertension. 

Is high diastolic blood pressure less dangerous than high systolic blood pressure?

No, high diastolic pressure is not less dangerous. Studies have found that elevated diastolic blood pressure with normal systolic blood pressure is associated with a significantly increased risk of cardiovascular events such as heart attack, stroke, atrial fibrillation (AFib), and peripheral arterial disease (PAD).

How do you fix high diastolic blood pressure?

The same treatments that are used to lower diastolic blood pressure are used for overall blood pressure control. 

Eating a heart-healthy diet, limiting salt intake, getting regular exercise, maintaining a healthy body weight, stopping smoking, avoiding excessive alcohol consumption, managing chronic anxiety, getting enough sleep, and other healthy lifestyle changes can help lower blood pressure. These same measures are also useful in preventing high blood pressure. 

If lifestyle modifications alone are not successful in controlling high blood pressure, your doctor may prescribe medications, such as beta-blockers, calcium channel blockers, ACE (angiotensin-converting enzyme) inhibitors, or angiotensin receptor blockers. 

Maintaining a healthful lifestyle is essential to keep your blood pressure under control long-term. Work closely with your doctor, especially when starting a new blood pressure medication or adding new blood pressure pills to your current regimen. 

Your blood pressure goals depend on your age and health history. The goal is to get your blood pressure to the recommended range without dropping either number too quickly. Low blood pressure can cause dizziness and lightheadedness, which can cause falls and injury. 

Talk to your doctor if you feel dizzy, lightheaded, weak, or fatigued. Your doctor will work with you to adjust the dose of blood pressure medications to achieve your goal blood pressure without dipping too low. 

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