A high top number on your blood pressure reading is called isolated systolic hypertension. It can happen from aging or several medical conditions and still needs treatment even if your low number is normal.
When your doctor takes your blood pressure, they’re measuring the pressure of your blood as it pushes against your artery walls. This measurement generates two numbers — systolic blood pressure and diastolic blood pressure.
For instance, with a blood pressure reading of 120/80 mm Hg, the first number is your systolic blood pressure reading, and the second number is your diastolic blood pressure reading.
When both of these numbers are higher than normal, you have high blood pressure (hypertension), which can put you at risk of serious health conditions.
But what if your systolic blood pressure is high and your diastolic blood pressure is normal?
This is a condition referred to as isolated systolic hypertension (ISH), which we’ll look at in more detail in this article.
ISH is when you have a systolic blood pressure reading of 140 mm Hg or higher, and a diastolic blood pressure reading of less than 80 mm Hg.
Like other types of high blood pressure, isolated systolic hypertension can raise your risk of:
- heart attack
- kidney disease
- heart failure
- other health conditions
Additionally, a 2015 study found that ISH can increase the risk of heart disease and death in young adults.
A blood pressure reading consists of two numbers — your systolic blood pressure and your diastolic blood pressure. But what do these numbers actually mean?
The first number is your systolic blood pressure. It’s a measurement of the amount of pressure placed on the walls of your arteries when your heart beats.
The second number is your diastolic blood pressure. It’s a measurement of the pressure on the walls of your arteries between heartbeats.
Understanding blood pressure readings
Blood pressure is measured in millimeters of mercury (mm Hg).
There are several different blood pressure categories, which are
|Systolic less than 120 mm Hg AND diastolic less than 80 mm Hg
|Systolic between 120–129 mm Hg AND diastolic less than 80 mm Hg
|Hypertension Stage 1
|Systolic between 130–139 mm Hg OR diastolic between 80–89 mm Hg
|Hypertension Stage 2
|Systolic of 140 mm Hg or higher OR diastolic of 90 mm Hg or higher
|Hypertensive crisis (a medical emergency)
|Systolic of higher than 180 mm Hg AND/OR diastolic higher than 120 mm Hg
One of the biggest challenges with high blood pressure is that it typically has no symptoms or warning signs. The only way to know whether your blood pressure is too high is to get it measured.
- at your doctor’s office or during a health checkup
- at a pharmacy with a digital blood pressure measuring device
- at home with a home blood pressure monitor
Blood pressure involves how much blood your heart pumps every minute, as well as the pressure exerted on the walls of your arteries by that blood.
As you age, your arteries lose some of their natural elasticity and are less able to accommodate the rush of blood. Plaque, which is fatty deposits on the artery wall, can also contribute to the stiffening of the arteries.
Blood pressure — particularly systolic blood pressure — naturally tends to increase with age. Because of this, there may be no identifiable cause of high blood pressure.
However, there are some medical conditions that can cause you to develop ISH. These conditions can affect your circulatory system, which can damage your blood vessels or contribute to artery stiffening.
Some of these conditions include:
- Anemia. With anemia, you don’t have enough red blood cells to carry oxygen to the tissues in your body. Damage can be caused to your blood vessels as your heart works harder to pump blood to the tissues of your body in order to deliver enough oxygen.
- Diabetes. If either type 1 diabetes or type 2 diabetes isn‘t well managed, high glucose levels in your blood can cause a variety of health problems, including conditions that affect your heart and circulatory system.
- Hyperthyroidism. Hyperthyroidism, or an overactive thyroid, occurs when your thyroid gland produces more thyroid hormones than necessary. Having high levels of thyroid hormone can affect almost every organ in your body, including your heart and circulatory system.
- Obstructive sleep apnea. With obstructive sleep apnea, the muscles in your throat relax too much and block your airway while you’re sleeping, causing your breathing to stop and start again. This can strain your cardiovascular system and lead to increases in blood pressure.
When high blood pressure isn‘t managed, it can cause damage to your arteries. This can affect many parts of your body and increase your risk of:
- Heart attack. Elevated blood pressure can damage your coronary arteries, which increases the risk of a blockage in one of your heart’s arteries.
- Stroke. Untreated high blood pressure can damage or weaken the arteries in your brain, which increases the risk of an ischemic stroke, hemorrhagic stroke, and transient ischemic attack (TIA).
- Heart failure. Elevated blood pressure can weaken the muscles of your heart, causing them to become too weak to pump blood efficiently to the rest of your body.
- Aneurysm. High blood pressure can weaken part of an artery, causing it to bulge out and possibly rupture.
- Kidney disease. The blood vessels in your kidneys can become damaged by untreated high blood pressure, resulting in your kidneys being unable to effectively filter toxins out of your blood.
- Vision loss. Damage to the blood vessels in your eyes can lead to bleeding in the retina and loss of sight.
- Dementia. Dementia or vascular dementia can occur when oxygen-rich blood flow to your brain is reduced.
Other risk factors include:
- certain medical conditions, such as hyperthyroidism, diabetes, and arterial stiffness
- obesity or a high body mass index (BMI)
- high salt intake, which can increase blood pressure
- smoking, which can stiffen the arteries
- heavy alcohol use
ISH can be treated like other forms of hypertension. The goal is to reduce your systolic blood pressure to below 140 mm Hg. This can be accomplished by lifestyle changes, medication, or both.
It’s important that treatment is balanced to reach a lower systolic blood pressure, but not reduce diastolic blood pressure too much. Lower-than-normal diastolic blood pressure may lead to heart damage.
If there’s an underlying condition that’s causing or contributing to ISH, your doctor will work to treat that as well.
A 2016 review of studies in older adults with ISH has found that the following medications had the greatest efficacy in reducing the risk of stroke and other cardiovascular events:
- Calcium channel blockers. Calcium channel blockers help the artery walls relax by blocking the pathway that causes blood vessel constriction.
- Thiazide-like diuretics. Thiazide-like diuretics reduce blood volume by helping your kidneys get rid of more sodium and water.
The following drugs were found to have less efficacy, however, they may still be effective in treating ISH:
- Angiotensin converting enzyme (ACE) inhibitors. (ACE) inhibitors block the formation of a specific enzyme that leads to the narrowing of blood vessels.
- Angiotensin receptor blockers (ARBs). ARBs block the action of a specific enzyme that can lead to blood vessel narrowing.
You may also need to make some lifestyle changes as part of your ISH treatment plan. These changes may include:
- Losing weight, if applicable. Losing weight can play a key role in helping to lower your blood pressure.
- Eating a heart-healthy diet. Your diet is thought to play a major role in the development of high blood pressure. Consider the Dietary Approaches to Stop Hypertension (DASH) diet, which is designed to prevent or treat high blood pressure. It emphasizes eating:
- whole grains
- low fat dairy products
- lean proteins
- nuts, seeds, and legumes
- Cutting back on salt. A high sodium intake is
associatedwith high blood pressure. This is why reducing your salt consumption can take some strain off your blood vessels and heart. Aim for less than 2,300 milligramsof sodium per day, according to the 2020–2025 Dietary Guidelines for Americans.
- Exercising. Not only can exercise help you lower your blood pressure, but it can also help you manage your weight and stress levels. Aim to perform some sort of aerobic exercise for at least 30 minutes most days of the week.
- Decreasing alcohol consumption. Try to limit your alcohol intake to one standard drink per day for women and two standard drinks per day for men.
- Quitting smoking if you smoke. Smoking can raise your blood pressure and also increase your risk of a heart attack, stroke, and other serious health conditions.
- Managing stress. Stress can raise your blood pressure, so finding ways to relieve it are important. Consider stress management techniques such as physical activity, meditation, deep breathing exercises, yoga, or spending time in nature.
You can help lower your risk of high blood pressure by practicing the lifestyle changes mentioned above.
Additionally, consider working with your doctor to carefully manage any preexisting health conditions that can contribute to high blood pressure, such as diabetes or hyperthyroidism.
You can also monitor your blood pressure at home if you’d like to keep a closer eye on changes in your blood pressure outside of your routine checkups.
The symptoms of high blood pressure are typically silent. Many people may not find out they have high blood pressure until they visit their doctor for a routine physical. If you don’t already have a primary care doctor, the Healthline FindCare tool can help you find a physician in your area.
You can also use a home blood pressure monitor to measure your blood pressure at home. You may want to consider monitoring your blood pressure if you:
- have overweight or obesity
- are pregnant
- have a family history of high blood pressure
- have been told by your doctor to check your blood pressure regularly
It’s important to keep a log of your readings. Keep in mind, though, that home blood pressure monitoring isn’t a substitute for a doctor’s visit. If you find that your readings are consistently high, contact your doctor to discuss them.
Isolated systolic hypertension is when your systolic blood pressure is high, but your diastolic blood pressure is normal. It can occur naturally with age or can be caused by specific health conditions, including anemia, diabetes, and hyperthyroidism.
ISH should still be treated even though your diastolic pressure is normal. This is because untreated high blood pressure, including ISH, can lead to health complications like a heart attack or stroke.
Be sure to have regular physical checkups with your doctor, during which your blood pressure is taken. If you have high blood pressure, your doctor will work with you to develop a plan that’s best for you.