Low Blood Pressure (Hypotension)
Hypotension Overview. Most people assume that you can’t be too thin, too rich, or have blood pressure that is too low. Many people with low blood pressure are athletes in prime physical condition.
They have strong cardiovascular systems and a reduced risk of heart attack and stroke. For these people, low blood pressure is an indication of health.
For others, extremely low blood pressure can be a cause of concern as it can signal an underlying problem, particularly when the blood pressure drops suddenly. Low blood pressure can be a dangerous condition that deprives the brain and other vital organs of nutrients and oxygen.
Many people who have hypotension (low blood pressure) exhibit no symptoms and appear healthy, but for many others, symptoms such as the following may be exhibited.
- Lack of concentration
- Rapid/shallow breathing
- Blurred vision
Sudden drops of blood pressure are particularly dangerous, as a change of just 20 mmHg can cause dizziness and fainting due to inadequate blood supply to the brain. Larger drops are especially dangerous and potentially life threatening, especially when complicated by bleeding, infections, and/or allergic reactions.
Additionally, chronic low blood pressure may increase the risk of dementia (similar to Alzheimer’s) in older adults. This is particularly the case when the diastolic pressure is lower than 70 for a prolonged period of time. Every drop of 10 mmHg increases the risk of dementia by 20%.
Current research believes “normal” blood pressure is lower than 120/80 and that “optimal” bp is 115/75. Most experts believe that a blood pressure of either less than 90 systolic or 60 diastolic (you only need one reading to be low) is considered to be lower than normal. But because normal ranges for blood pressure can vary significantly from person to person, chronic low blood pressure is generally diagnosed only when there are noticeable symptoms and signs.
When evaluating a patient for low blood pressure, the end-goal is to determine the underlying cause. This helps form the strategy for treatment. Your doctor may conduct one or more of the following to diagnosis your condition:
- Blood tests – provides information about your overall health, as well as whether you have specific conditions such as hypoglycemia or anemia that can cause low blood pressure
- ECG/EKG (Electrocardiogram) – this test, which is non-invasive and is performed on an outpatient basis, detects irregularities in your heart rhythm, structural abnormalities of the heart, and problems with the blood/oxygen supply to the heart muscle.
- Echocardiogram – This test produces an image of your heart via the same technology used to view the fetus in the womb. Images of the heart may show abnormalities in your heart muscle and/or valves.
- Valsalva maneuver – This test checks the functioning of your autonomic nervous sytem by analyzing your blood pressure and heart rate after several deep breathing cycles.
- Tilt-table test – This test is usually used when you have orthostatic or nerually mediated hypotension. In this test, you lie on a table that is tilted to raise your upper body. This simulates the standing motion and your body’s reactions are evaluated throughout.
There are a variety of factors that can lead to low blood pressure:
- Pregnancy – Blood pressure commonly drops by as much as 5-10 points systolic and 10-15 diastolic during the first 24 weeks of pregnancy due to the expansion of the woman’s circulatory system
- Medications – Not surprisingly, many drugs used to treat hypertension (high blood pressure) and heart disease can trigger unexpectedly low blood pressure. Your doctor may need to adjust your dosage and/or medication. Other drugs to treat Parkinson’s disease, depression, and erectile dysfunction (e.g. Viagra) can also cause low blood pressure.
- Heart Problems – Heart problems such as bradycardia (low heart beat rate), heart valve problems, and heart attack/failure can lead to low blood pressure. In these conditions, the heart is not able to pump enough blood.
- Endocrine Problems – Thyroid problems (underactive or overactive), Addison’s disease (adrenal insufficiency), low blood sugar, and diabetes can all trigger low blood pressure.
- Blood Loss – Any significant trauma leading to a significant loss of blood can lead to low blood pressure. This is a result of the drop in blood volume available.
- Dehydration – In dehydration, your body loses more water than you take in. Dehydration is usually a result of diarrhea, vomiting, diuretic overuse, and strenuous exercise. The drop in volume can cause weakness, dizziness, and fatigue.
- Nutritional Deficiencies – Deficiencies in vitamin B-12 and folic acid can lead to anemia, which then in turn can lead to low blood pressure
- Anapylaxis (allergic reaction) – Severe allergic reactions, usually in situations where the patient is extremely allergic to either certain drugs (e.g. penicillin), foods (e.g. peanuts), or bee/wasp stings, leads to anaphylatctic shock. This may include sudden large drops in blood pressure.
- Septic Shock (severe infection) – Septic shock occurs when an infection leaves the original point of infection and enters the bloodstream. The bacteria in the infection produce toxins that affect your blood pressure and can lead to a potentially life-threatening decline in blood pressure.
- Orthostatic Hypotension (Postural Hypotension) – This is a sudden decrease in systolic blood pressure as a result of standing up. More information can be found here.
- Shy-Drager Syndrome – This is a rare disorder that causes progressive damage to the autonomic nervous system. This system controls such involuntary functions like blood pressure, heart rate, breathing, and digestion.
- Postprandial Hypotension – Postprandial hypotension is a sudden drop in blood pressure after a meal. It is a problem almost exclusively affecting older adults. After a meal, blood pools to your digestive tract. Usually, your body compensates by increasing your heart rate and constricting blood vessels. In postprandial hypotension, this mechanism fails for some reason and blood pressure drops. This problem is commonly seen in people with autonomic nervous system orders (e.g. Parkinson’s disease) or in people taking medication for hypertension.
- Neurally mediated hypotension – This condition is the opposite of orthostatic hypotension. Long periods of standing triggers a drop in blood pressure, thus leading to typical symptoms of hypotension such as dizziness, nausea, and fainting. Neurally mediated hypotension primarily affects young people and is driven by a miscommunication between the heart and the brain. Long periods of standing cause blood to pool in your legs. The brain signals the heart to compensate. In nerually mediated hypotension, the heart’s left ventricle actually signals the brain that blood pressure is too high and thus the brain incorrectly lessens the heart rate and further reduces the blood pressure.
Low blood pressure that does not exhibit any symptoms usually does not require treatment. In symptomatic low blood pressure, your doctor will determine the appropriate course of action by determining the underlying cause of the hypotension. Common causes of hypotension, such as diabetes, heart failure, hypothyroidism, and dehydration each have different courses of treatment.
If it is not immediately clear what the underlying cause of the hypotension is, your doctor may place you on a course of treatment designed to raise your blood pressure directly and to alleviate any symptoms you may be having. Typical treatment options to raise blood pressure include:
- Increased sodium intake – salt is a key driver of high blood pressure and increasing your sodium intake can help alleviate low blood pressure symptoms.
- Increased hydration – increasing the volume of fluid in your body by drinking more water can help increase blood pressure.
- Compression stockings – Blood pooling in your legs can be somewhat mitigated by wearing elastic stockings and leotards.
- Medication – The drug Midodrine has traditionally been used to raise the standing blood pressure of people with orthostatic hypotension, but use of the drug can be problematic as those same people tend to have high blood pressure when lying or sitting (supine pressure). A new drug called Mestinon show promise as it increases standing blood pressure without affecting supine pressure.
Depending on the underlying condition driving your low blood pressure, certain lifestyle modifications can help you manage your symptoms:
- Drink more water
- Drink less alcohol – alcohol is dehydrating and can lead to lower blood pressure
- Follow a healthy diet – focus on getting the nutrients you need by eating a variety of grains, fruits, vegetables, and lean meats.
- Go slow – you may be able to reduce your symptoms of dizziness and lightheadedness by sitting or standing slowly
- Eat small, low-carb meals – this helps prevent blood pressure form dropping too sharply after meals. Drinking caffeinated drinks may also help raise blood pressure, but check with your doctor first as caffeine can cause other problems.