Do you feel suddenly light-headed, perhaps even faint, when you stand up from sitting or lying down? If so, you likely have a form of low blood pressure known as orthostatic hypotension.
Many of us will experience this periodically, and it usually lasts for only a few seconds. It is generally not a cause for alarm.
What happens is that gravity causes blood to pool in your legs while you are sitting, decreasing your blood pressure because there is less blood in circulation back to your heart to pump.
Under normal circumstances, baroreceptor cells near your heart and neck arteries sense this lower blood pressure and send notifications to your brain. Your brain in turn tells your heart to compensate, to beat faster and pump more blood, thereby stabilizing your blood pressure. In addition, these cells cause blood vessels to narrow, which increases resistance to blood flow and increases blood pressure. Orthostatic hypotension is what we call the low blood pressure which results when something disrupts our compensation mechanism – such as suddenly standing up and returning that pool of blood back into circulation.
Orthostatic hypotension can also be caused by dehydration, thyroid conditions, Addison's disease, low blood sugar, diabetes, Parkinson's disease, multiple system atrophy, Lewy body dementia, pure autonomic failure and amyloidosis.
Age can also be a factor. As your body ages, the ability yourbaroreceptors can be slowed. Also, when you age, it may be harder for your heart to beat faster and compensate for drops in blood pressure.
In addition to the momentary dizziness, you may also experience:
- Blurry vision
Brief and irregular episodes of orthostatic hypotension are nothing to worry about, but longer or more frequent of may be a sign of more serious issues. In these cases, see your doctor.
In making her diagnosis, your doctor will measure your blood pressure both while you are sitting and while you are standing and will compare the measurements. If you have a drop of 20 millimeters of mercury (mm Hg) in your systolic blood pressure or a drop of 10 mm Hg in your diastolic blood pressure within two to five minutes of standing up, or if standing causes signs and symptoms, your diagnose orthostatic hypotension.
Treatment will likely involve some lifestyle changes. Your doctor will want you to ensure you are drinking enough fluids, and little or no alcohol. Your doctor may also suggest exercise programs to strengthen your leg muscles.
If lifestyle changes are insufficent to address the ailment, your doctor may prescribe fludrocortisone, which is used to help increase the amount of fluid in your blood, or midodrine to raise standing blood pressure levels.