Blood pressure lower than 90/60 mm of Hg is referred to as low blood pressure, or hypotension. The first number is the measure of pressure in the arteries when the heart beats and fills blood in them. The second number is the pressure in the arteries when the heart is at rest between two beats. In healthy people, the measure is around 120/80 mm Hg. Low pressure reduces the flow of blood in the blood vessels, which affects the delivery of oxygen and nutrients to different parts of the body like brain, heart and kidney. Low blood pressure is characterized by the symptoms of low blood flow rather than reduced blood pressure.
In general, people who exercise regularly and maintain a healthy body weight tend to have low blood pressure. But they may not have any symptoms of the condition. As the pressure on the blood vessels become low, the risk of diseases, like stroke, kidney, and heart problems is considerably reduced with hypotension. Thus, low blood pressure is in fact beneficial if the condition does not cause any serious symptoms or affect the functioning of an organ.
Hypotension may be of concern if it occurs suddenly, and if it affects the blood flow to the brain resulting in lightheadedness and dizziness. When adequate amounts of oxygen and nutrients are not delivered, it may damage the organs. Symptoms of low blood pressure are felt during sudden changes from a sitting position, to a standing position. If the amount of blood delivered to the blood vessels supplying the heart is less, it may lead to chest pain and even heart attack. Low blood pressure may reduce the blood flow to the kidneys which affects the elimination of waste materials from the blood. This may lead to an increase in the levels of urea and creatinine in blood. Persistently low pressure of the blood may cause multiple organ failure resulting in a condition called ‘shock’.
The underlying causes of low blood pressure are equally important as the condition itself.
Some of the common causes of hypotension include:
- Heart problems – Heart valve problems, heart attack and heart failure may all lead to low blood pressure.
- Endocrine issues – Thyroid problems and adrenal insufficiency are also known to cause hypotension. Low blood sugar levels and diabetes may also lead to this condition.
- Blood loss
- Severe infection
- Allergic reaction