Orthostatic intolerance

Orthostatic intolerance (OI) is a condition characterized by symptoms that occur when a person stands up, and which improve or resolve when the person lies back down. Symptoms can include lightheadedness, fainting, rapid heartbeat, and other signs of the body's inability to adapt to the upright posture.

Causes

OI can be caused by a variety of conditions, including Postural Orthostatic Tachycardia Syndrome (POTS), neurally mediated hypotension (NMH), and chronic fatigue syndrome (CFS). It can also be a side effect of certain medications, or a symptom of dehydration or prolonged bed rest.

Symptoms

Symptoms of OI can vary widely from person to person, but commonly include lightheadedness, fainting, rapid heartbeat, and fatigue. Other symptoms can include nausea, headache, sweating, and tremors. These symptoms are typically triggered by standing up, and improve or resolve when the person lies back down.

Diagnosis

Diagnosis of OI typically involves a physical examination and a detailed medical history. Tests may include a tilt table test, in which the patient is strapped to a table that is then tilted to simulate standing up. Blood pressure and heart rate are monitored during this test to see how the body responds to the change in posture.

Treatment

Treatment for OI typically involves managing the underlying condition that is causing the symptoms. This can include medication, lifestyle changes, and physical therapy. In some cases, treatment may also involve addressing any psychological factors that may be contributing to the symptoms.

See also

• Postural Orthostatic Tachycardia Syndrome
• Neurally mediated hypotension
• Chronic fatigue syndrome