What Do The Numbers Mean?


2015-1206 What Do the Numbers Mean

There is no avoiding it, and there is no reason to avoid it. Each time we visit a doctor we have to sit still while somebody tests our blood pressure. Although many doctors use a machine to assess blood pressure, others use a stethoscope and cuff. From the patient’s point of view, the results are the same. The cuff inflates, tightens around your arm, pinches for a few seconds, and then cuff deflates.

Afterward, you hear, or ask to hear, the result. The result is usually expressed as two numbers, or a few words based on the numbers, but what do the numbers really mean?

According to the American Heart Association, “when the reading is 117/76 mm Hg (read as 117 over 76 millimeters of mercury), the upper number 117 is the systolic pressure (see below for definition and guideline) and the lower number is the diastolic pressure (see below for definition and guideline).”


The top number, which is also the higher of the two numbers, measures the pressure in the arteries when the heart beats (when the heart muscle contracts).


The bottom number measures the pressure in the arteries between heartbeats (when the heart muscle is resting between beats and refilling with blood).


The systolic and diastolic numbers determine whether your blood pressure is too high, too low, or just right. The following chart, provided by Blood Pressure UK, illustrates a typical interpretation of blood pressure guidelines.


Blood Pressure Ranges

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High Blood Pressure

You may have high blood pressure (hypertension) if either the systolic or diastolic number is higher than it should be over a number of weeks. High blood pressure increases the strain on your heart and blood vessels. Over time, the extra strain increases your risk of a heart attack, stroke, kidney disease, and some types of dementia.

The good news about high blood pressure is you may be able to control it with permanent lifestyle changes such as:

  • Consuming less salt
  • Eating more fruit and vegetables
  • Exercising more often
  • Lowering your weight
  • Drinking less alcohol

Low Blood Pressure

Most doctors do not consider low blood pressure (hypotension) a problem unless it leads to signs and symptoms, which may include:

  • Dizziness
  • Fainting
  • Fatigue
  • Problems concentrating
  • Blurry vision
  • Nausea
  • Clammy, pale skin
  • Shortness of breath

Mildly low blood pressure may be a sign of good health and a decreased risk of heart disease, but in some people, low blood pressure can be a problem. However, continually low blood pressure, or a sudden drop in blood pressure, can cause serious health problems.

According to Everyday Health, “An onset of hypotension is more likely to occur when you:

  • Are on bed rest for a long period of time, and then resume an upright posture
  • Are in your first 24 weeks of pregnancy
  • Have lost a lot of blood
  • Are taking certain medications, such as blood pressure lowering medications, certain heart medications, certain Parkinson’s disease medications, tricyclic antidepressants, or medications to treat erectile dysfunction
  • Have a heart problem, such as a very slow heart beat, heart valve problems, heart attack, or heart failure
  • Have an endocrine problem, such as hypothyroidism, parathyroid disease, Addison’s disease, low blood sugar, or diabetes
  • Have a severe infection that enters your blood stream
  • Are experiencing anaphylaxis, a life-threatening allergic reaction
  • Have a neural disorder that affects your blood pressure
  • Have a nutrient deficiency, such as low vitamin B12 and folic acid levels”

Anyone can develop low blood pressure, but certain groups of people are more likely to experience it. For instance, up to 30 percent of older adults will experience sudden drops in blood pressure while sitting or standing.


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Information in this post was provided by the American Heart Association, WebMD, Blood Pressure UK, and Everyday Health.



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