Low Blood Pressure (Hypotension): Causes, Symptoms, Diagnosis and Treatment

Many people worry about high blood pressure as it may increase the risk of heart attack and stroke, but low blood pressure can also cause a number of health problems.

What is Low Blood Pressure?

Low blood pressure, also known as hypotension, is when your blood pressure drops below the normal range. Generally, if the blood pressure reading is less than 90/60 mmHg, it is considered as low blood pressure.

The first number (systolic) refers to the amount of pressure in your blood vessels when your heart beats, pumping the blood through your arteries to the rest of your body, and the second number (diastolic) refers to the amount of pressure in your arteries when your heart is at rest between beats.

Low blood pressure may cause an inadequate blood flow to all parts of your body, including the brain, heart, and other vital organs. As a result, your body do not get enough oxygen and nutrients. Thus, the affected organs and cells are begin to malfunction. If left untreated, low blood pressure can cause long-term damage to the heart and brain, which can be life-threatening.

What Causes Low Blood Pressure?

Low blood pressure can be caused by many things, including:

Dehydration

Dehydration is the most common cause of low blood pressure. When you’re dehydrated, your total blood volume decreases, leading to a drop in blood pressure.

Diarrhea, vomiting, overuse of diuretics and strenuous exercise can all lead to dehydration.

Heart problems

These conditions may cause low blood pressure because they prevent the body from being able to pump adequate amount of blood. Some heart problems that can lead to low blood pressure include irregular heartbeat (arrhythmia), heart attack and heart failure.

Blood loss

Blood loss due to injury or severe internal bleeding reduces the amount of blood in the body, thus lead to a drop in blood pressure.

Severe infection

When an infection in the body enters the bloodstream, it can lead to a life-threatening drop in blood pressure called septic shock.

Pregnancy

Blood pressure is likely to drop when you are pregnant, especially during the first 24 weeks of pregnancy.

Medications

Some types of medications that can cause low blood pressure include:

  • High blood pressure medications, such as diuretics, ACE inhibitors, alpha-blockers, and beta blockers.
  • Certain Parkinson’s disease medications, such as dopamine agonists and levodopa/carbidopa (Sinemet)
  • Depression medications, such as amitriptyline (Elavil)

What are the Symptoms of Low Blood Pressure?

Some of the common signs and symptoms of low blood pressure include:

  • Dizziness or lightheadedness
  • Fainting
  • Nausea
  • Fatigue
  • Blurred vision
  • Weakness
  • Cold, pale skin
  • Rapid, shallow breathing
  • Lack of concentration

How is Low Blood Pressure Diagnosed?

Your doctor will ask about your symptoms and use a blood pressure test to diagnose low blood pressure by placing a blood pressure cuff around your upper arm. The cuff will tighten on your arm, and the monitor will measure your systolic and diastolic pressure.

Depending on your medical history and symptoms, your doctor may also perform one or more of the following tests.

Blood test

This test can provide information about your overall health as well as whether you have anemia, diabetes, or other conditions associated with hypotension.

The blood test involves your doctor or the lab-technician drawing some of your blood, typically from a vein in your arm.

Electrocardiogram (ECG)

An electrocardiogram is used to check for heart problems that may cause your blood pressure to drop. An ECG is able to detect irregularities in your heart rhythm, heart structural abnormalities, and problems with the blood supply to your heart muscle. It can also tell if you’re having a heart attack or have had one in the past.

The noninvasive test involves the attachment of sticky patches (electrodes) to the skin of your chest, arms and legs. The patches detect your heart’s electrical signals, while a machine records them and displays them on the screen as a graph.

Tilt table test

If you have repeated, unexplained episodes of lightheadedness, dizziness or fainting, your doctor may order a tilt table test to determine if the symptom is related to your heart rate or blood pressure.

During the test, you will be placed on a table that has the ability to switch you from lying down to an upright position very quickly. Your body’s reaction to being switched between these two positions will be monitored with an electrocardiogram.

A tilt table test can be used to assess changes in blood pressure at different angles and is useful in diagnosing orthostatic hypotension and neurogenic mediated hypotension.

How is Low Blood Pressure Treated?

Treatment of low blood pressure depends on the cause. For example:

  • If your hypotension is caused by dehydration, you will need to increase your water intake.
  • If medicine is causing your low blood pressure, the medicine may be changed or stopped.
  • If you have a severe infection, treating the infection can help return your blood pressure to normal.

Your doctor may advise you to take precautions to prevent episodes of low blood pressure, such as avoiding dehydration, limiting alcohol consumption, and not standing up too quickly.

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