Central  South  Dakota  Medical News
The Clinical View
by Phillip Hoffsten,M.D.
15 July 04

HOW LOW SHOULD YOUR BLOOD PRESSURE BE?

     In 1925, the New York Life Insurance Company published a table showing the blood pressures for their clients that purchased a life insurance policy.  The table showed a slow increase in the mortality rate among these policy holders until the blood pressure reached 140/90 mm of mercury.  At that point, there was a sharp increase in the mortality rate as blood pressures went higher.  The medical profession took this data to mean that blood pressures up to 140/90 or less were “normal”.  Note this definition simply ignored the fact that mortality rates were increasing as blood pressures went from 125 to 130 to 135 to 140.

     In the 1980’s a suspicion was growing that 140/90 was not “a normal blood pressure”.  Studies began at that time and were published in the 1990’s showing very clearly that a “normal blood pressure” was 110/80 or less.  Specifically, what this meant was that individuals with blood pressures of 100 or 105 or 110, all have the same mortality rate.  But at 110 mm of mercury or higher, mortality rates begin to increase.  So now we have good information stating that a normal blood pressure is 110/80 mm of mercury or less.  When a blood pressure reaches 120 mm of mercury or higher, treatment with a medication to get the blood pressure back down clearly shows a benefit in avoiding heart attacks and strokes which are the leading killers in our country.

     Trying to sell this idea that a lower a blood pressure is better has been very difficult.  A patient came to the clinic stating that she needed a checkup.  Her health profile was reviewed and as part of it, a blood pressure of 135/85 was seen.  She was slightly overweight and distinctly diabetic.  Up to this point in her life, she had never taken medications and wanted to avoid the use of medications.  Try as I would, I was unable to convince her that medication treatment of both her diabetic condition and her blood pressure was an indicated step.  She said that she wanted to treat this with diet and exercise.  I pointed out to her that the statistical likelihood of her being able to control both the diabetes and the blood pressure with diet and exercise was less than 2% of the population.  Be that as it may, she said she wanted to treat her situation with diet and exercise.

     She was instructed to get a blood pressure cuff and monitor her blood pressure in her own home.  A month later, she returned with multiple blood pressures mostly in the 110 to 130 mm of mercury range.  One weekend when multiple family members came to visit and she became more tired than usual, her blood pressures rose into the 140 to 160 range.

     After she had been attempting her increased diet and exercise program for a month, she returned with the above two records.  She was again instructed that medications were appropriate and the single most effective lifesaving medication was to control her blood pressure.  She was started on a medication and returned a month later with another record of blood pressures.  Now she was concerned that her blood pressure was too low and she just felt terrible.  In fact, her blood pressures had dropped to values between 100 and 110 mm of mercury most of the time.  There were no values higher than 130.  She was absolutely convinced that this was too low for her and that she felt better with the higher blood pressure.

     So I reviewed with her the findings that would suggest that her blood pressure was too low.  I asked if she got dizzy or felt as if she would pass out when she got up to walk about.  She indicated that she had no trouble getting up and walking about.  I asked if she had had any fainting spells such as when she was standing up for prolonged periods of time.  She indicated that she had had no fainting spells.  I asked if she had changed her activity so that she couldn’t carry on her normal daily activities.  She indicated that her activity schedule was normal.  Her blood pressure monitor had a pulse check on it in addition.  I asked if her pulse was running faster than we have had prior to starting the medication.  Checking the record, her pulse had remained exactly the same.  I pointed out to her that the above findings would not suggest that her blood pressure was too low as she had none of those findings.  Various blood tests were done to see if there was a side effect of the medication and none was seen.

     I then inquired as to why she thought her blood pressure was too low.  As often happens, she related that she had been talking to several friends about her new medication and her blood pressure and they had commented that they thought that her blood pressure was too low.  I never cease to be amazed about how little credibility doctors have when it is compared to the opinion of a person’s friends.

 Long discussions ensued and eventually I have been able to convince her that a normal blood pressure for a diabetic is 110 mg of mercury or less.  Pressures higher than this are associated with progressive kidney damage, early onset of heart attacks and strokes.

     The data upon which the above information is based has been generated in the last 15 years.  It is now very clear that a normal blood pressure is 120 mg of mercury or less and an ideal blood pressure of 110 mg of mercury or less.  There is no such thing as “normal high blood pressure”.  There is also no basis for a person believing that they feel better with a higher blood pressure.

     In summary, high blood pressure is the leading cause of strokes, heart failure, progressive kidney damage with diabetics, and it is a major contributor for heart attacks.  Controlling it at the lower levels mentioned above, has been demonstrated to be highly effective in preventing those complications.  Diet and exercise alone works for less than 2% on the population.  It may work for a month or three months or six months but almost everyone will “fall off the wagon” and blood pressures go back up as the diet and exercise program wanes.  The use of medication to control the blood pressure has clear demonstrated evidence that the complications of high blood pressure can be prevented.  The healthcare providers at your local clinics are well aware of this information and will work with you to get blood pressures down into the normal range.