Orthostatic hypotension (postural hypotension)
DEFINITION
Orthostatic hypotension — also called postural hypotension — is a form of low blood pressure that happens when you stand up from sitting or lying down. Orthostatic hypotension can make you feel dizzy or lightheaded, and maybe even faint.
Orthostatic hypotension is often mild, lasting a few seconds to a few minutes after standing. However, long-lasting orthostatic hypotension can be a sign of more-serious problems, so talk to your doctor if you frequently feel lightheaded when standing up. It’s even more urgent to see a doctor if you lose consciousness, even momentarily.
Mild orthostatic hypotension often doesn’t need treatment. Many people occasionally feel dizzy or lightheaded after standing, and it’s usually not cause for concern. The treatment for more-severe cases of orthostatic hypotension depends on the cause.
CAUSES
When you stand up, gravity causes blood to pool in your legs. This decreases blood pressure because there’s less blood circulating back to your heart to pump.
Normally, special cells (baroreceptors) near your heart and neck arteries sense this lower blood pressure and send signals to centers in your brain that in turn signal your heart to beat faster and pump more blood, which stabilizes blood pressure. In addition, these cells cause blood vessels to narrow, which increases resistance to blood flow and increases blood pressure.
Orthostatic or postural hypotension occurs when something interrupts the body’s natural process of counteracting low blood pressure. Orthostatic hypotension can be caused by many different conditions, including:
- Dehydration. Fever, vomiting, not drinking enough fluids, severe diarrhea and strenuous exercise with excessive sweating can all lead to dehydration. When you become dehydrated, your body loses blood volume. Mild dehydration can cause symptoms of orthostatic hypotension, such as weakness, dizziness and fatigue.
- Heart problems. Some heart conditions that can lead to low blood pressure include extremely low heart rate (bradycardia), heart valve problems, heart attack and heart failure. These conditions may cause orthostatic hypotension because they prevent your body from being able to respond rapidly enough to pump more blood when needed, such as when standing up.
- Endocrine problems. Thyroid conditions, adrenal insufficiency (Addison’s disease), low blood sugar (hypoglycemia) and, in some cases, diabetes can trigger low blood pressure. Diabetes can also damage the nerves that help send signals regulating blood pressure.
- Nervous system disorders. Some nervous system disorders, such as Parkinson’s disease, multiple system atrophy, Lewy body dementia, pure autonomic failure and amyloidosis, can disrupt your body’s normal blood pressure regulation system.
- After eating meals. Some people experience low blood pressure after eating meals (postprandial hypotension). This condition is more common in older adults.
SYMPTOMS
The most common symptom of orthostatic hypotension is feeling lightheaded or dizzy when you stand up after sitting or lying down. This feeling, and other symptoms, usually happens shortly after standing up and generally lasts only a few seconds. Orthostatic hypotension signs and symptoms include:
- Feeling lightheaded or dizzy after standing up
- Blurry vision
- Weakness
- Fainting (syncope)
- Confusion
- Nausea
When to see a doctor
Occasional dizziness or lightheadedness may be relatively minor — the result of mild dehydration, low blood sugar, or too much time in the sun or a hot tub, for example. Dizziness or lightheadedness may also happen when you stand after sitting for a long time, such as in a lecture, concert or church. If these symptoms happen only occasionally, it’s usually not cause for concern.
It’s important to see your doctor if you experience frequent symptoms of orthostatic hypotension because they sometimes can point to more-serious problems. It can be helpful to keep a record of your symptoms, when they occurred, how long they lasted and what you were doing at the time. If these occur at times that may endanger you or others, discuss this with your doctor.
