Orthostatic hypotension is characterized by a decrease in systolic blood pressure of 20mm Hg or 10mm Hg in diastolic blood pressure.

This sudden drop in blood pressure may appear when you sit down or stand up.

Normally, when you stand up quickly, your nerves and arteries work together to counter the force of gravity and keep your blood evenly distributed throughout your body. Your heart beats faster, your arteries narrow, more blood circulates, and blood pressure stabilizes. But many diseases and medications common to older people can interrupt this natural process. This can cause a sudden drop in your systolic blood pressure (the upper number of your blood pressure).

With orthostatic hypotension, gravity causes your blood to pool in your legs when you sit down or get up quickly after sitting or lying down. 

For a short time there is not enough blood to flow to your heart, brain and the rest of your body. 

This type of hypotension causes dizziness within three minutes of sitting or standing. It lasts from a few seconds to several minutes. In addition to feeling weak, you may feel nauseous and have pale or clammy skin.

The causes of orthostatic hypotension

There are many different causes of orthostatic hypotension, including dehydration, medications, and underlying medical conditions.

Dehydration is one of the most common causes. When the body is dehydrated, it doesn’t have enough fluid to maintain proper blood pressure.

Medications such as diuretics, beta blockers, and calcium channel blockers can also cause it by affecting the body’s ability to regulate blood pressure.

Underlying medical conditions such as heart disease, diabetes, and Parkinson’s disease can also lead to orthostatic hypotension.

Treatment for orthostatic hypotension depends on the underlying cause. If dehydration is the cause, increasing fluid intake is the most important treatment measure. If a medication is causing it, changing or stopping the medication may be necessary. In some cases, wearing compression stockings or taking certain medications can help to improve blood flow and reduce symptoms.

Here are examples of some diseases that can lead to sudden low blood pressure:

Sudden low blood pressure can also be caused by long-term bed rest, age-related nerve problems, anemia (not enough red blood cells), or your body’s nerves reacting incorrectly. 

Certain medications such as anti-parkinsonian drugs, some antidepressants, and drugs to treat erectile dysfunction can also cause orthostatic hypotension. Taking certain high blood pressure medications can also affect your body’s response to sitting or standing.  

Treatments

Treatment depends on the underlying cause.

If dehydration is the cause, increasing fluid intake is the most important treatment measure.

If a medication is causing orthostatic hypotension, changing or stopping the medication may be necessary. In some cases, wearing compression stockings or taking certain medications can help to improve blood flow and reduce symptoms.

Management of neurogenic orthostatic hypotension

Orthostatic hypotension is a medical condition which can be caused by either lesions in the sympathetic neurons (neurogenic orthostatic hypotension) or other underlying medical conditions (non-neurogenic orthostatic hypotension). To ascertain this, blood pressure and heart rate measurements are taken at the bedside. While fludrocortisone has traditionally been used to treat this, its use has been known to cause renal and cardiac failures as well as increase hospitalization risk. In order to distinguish the difference between neurogenic and non-neurogenic pathways, norepinephrine agonists or precursors such as droxidopa will work better for peripheral denervation while norepinephrine reuptake inhibitors have better results with central autonomic dysfunction.