Orthostatic hypotension (OH) is a frequently reported condition that causes a sudden decrease ≥ 20mm Hg in systolic blood pressure or ≥10 mm Hg in diastolic blood pressure, within 3 minutes of standing up from a horizontal or sitting position. Orthostatic hypotension may be symptomatic or not, and the symptoms range from mild to significant. Orthostatic hypotension is otherwise known as postural hypotension, since a change of posture is responsible for the sudden-onset episode of decreased blood pressure.
Orthostatic hypotension is defined as an episode of sudden blood pressure (BP) drop, in three or fewer minutes after assuming a standing position, when one was previously lying supine or sitting. In order for the episode to be substantiated as orthostatic hypotension, the BP decrease should amount to 20 mmHg or more in the systolic blood pressure or to 10 mmHg or more in the diastolic blood pressure. In some cases, both the systolic and diastolic blood pressure drop.
Some OH cases are asymptomatic and do remain undiagnosed. Symptomatic OH produces typical symptoms that vary in terms of severity. One of the most commonly reported symptoms is light-headedness and dizziness . A 2014 study reported that 20% of the patients with orthostatic hypotension felt light-headed when standing up. Considerable weakness, nausea, blurred vision and disorientation are also frequently reported symptoms. Fainting is a manifestation of orthostatic hypotension that is significantly severer than the aforementioned ones, although it is less common. The clinical picture is completed by the onset of headaches, shoulder ache or neck pain and chest tightness or dyspnea, on some occasions . The most debilitating effect that OH can exert on a patient is generalized seizures, which have been rarely described. Some individuals experience an aggravation of the symptoms following a heavy meal or physical exercise.
Orthostatic hypotension typically affects senior citizens, even though it is not uncommon amongst the younger population   .
The diagnosis of orthostatic hypotension is accurate, once blood pressure is measured in a patient who has been in a supine position for minimum 3 minutes, after standing up, as well as 3 and 5 minutes after they stand up. The last measurement is used to detect the extent to which blood pressure may drop upon standing but is not necessary for a decisive diagnosis . Further tests are required in order to unveil the cause of the condition.
A detailed medical history is necessary, including symptoms elicited by OH, medications that the patient is taking and autonomic failure indications, such as severe constipation, incontinence, irregular sweating or tingling sensation of the feet. Physical examination may reveal dry skin and a neurological evaluation should be carried out to look for anything suggestive of Parkinson's disease.
Blood laboratory testing includes a complete blood count, ΗbA1c to diagnose diabetes, serum and urine protein electrophoresis, vitamin B12 and ANA autoantibodies. Plasma catecholamines are also measured, both in a standing and supine position; the measurement needs to take place when the patient is relaxed in a supine position and when they have stood up for at least 5 minutes.