Lets start out with what is low blood pressure?
Normal blood pressure is usually in the range of 120/80 (systolic/diastolic). In healthy people, especially athletes, low blood pressure is a sign of good cardiovascular (heart and blood vessel) health. But low blood pressure can also be a sign of an underlying problem especially in the elderly where it may cause inadequate blood flow to the heart, brain, and other vital organs. Low blood pressure is referred to as Hypotension which is any reading less than 90/60.
You need to have only one of those two numbers in the low range for your blood pressure to be considered lower than normal. In other words, if your systolic pressure is a perfect 115, but your diastolic pressure is 50, you are considered to have lower than normal blood pressure. On the other hand, blood pressure readings are patient-specific. What might be low blood pressure for one patient may not be for another. That is a good reason to have a regular checkup so you and your doctor know what a normal blood pressure reading is for you.
What are the factors that affect blood pressure?
Blood pressure is determined by 3 main factors:
- Cardiac output (the rate at which blood is pumped from the heart).
- The volume of blood in the blood vessels. A decreased amount of blood in the body is called hypovolaemia.
- The capacity of the blood vessels (as determined by their internal diameter)
What could be the cause of low blood pressure?
Conditions that reduce the volume of blood, reduce cardiac output (the amount of blood pumped by the heart), and medications are frequent causes of low blood pressure. In some instances, low blood pressure can be a sign of serious, even life-threatening disorders. And although the reason for lower than normal blood pressure isnt always clear, doctors know that the following factors can cause or contribute to low and sometimes to dangerously low readings:
- Moderate or severe bleeding
- Severe inflammation of organs inside the body
- Weakened heart muscle
- Pulmonary embolism
- A slow heart rate
- Drug toxicity
- An abnormally fast heart rate (tachycardia)
- Allergic reactions
- Nutritional deficiencies
Certain diseases and disorders can cause chronic low blood pressure
- Vasovagal reaction
- Postural (orthostatic) hypotension
- Micturition syncope
- Adrenal insufficiency
- Anaphylaxis (anaphylactic shock)
- Shy-Drager syndrome
- Neurally Mediated Hypotension
This is a short list and by no means covers all the disorders and diseases that can cause low blood pressure. If you are experiencing low blood pressure, you should consult your physician.
What are the symptoms associated with low blood pressure?
If you would like to know more about the symptoms associated with low blood pressure, as well as facts regarding specific disorders, you may find it helpful to read my article on Neurally Mediated Hypotension. You may also like to read my article on the various treatments for low blood pressure.