Hypertension Origin And Statistics

About 50 million people in the U.S. suffer from hypertension. It is more common among women than men, but is even more common among black women, particularly after the menopause and beyond age 65. There is a public health crisis going on, as Ref. 2 describes that 75 % of the 50 million Americans who have hypertension are at risk for getting cardiovascular complications such as heart attacks or strokes.

There are deficiencies in diagnosing and treating hypertension as it is painless and people who should have their blood pressure measured regularly do not get this done.

The authors describe that many physicians are not aware of the 1997 guidelines from the Joint Committee (Ref.1) and as a result they use old outdated much higher cutoff points before treatment is instituted. There are also problems with under- and overtreatment according to Ref.2. Hyman et al.(Ref. 3) reiterates that many physicians have much higher treatment thresholds than the Joint Committee's 140/90 target, which leads to underdiagnosing hypertension and unwillingly putting patients at risk by not treating them. Also, these authors observed that once treatment has been started, patients are not treated adequately to normalize their blood pressures.

Most people (85 to 90%) with hypertension have "primary hypertension", which is also known under the name "essential hypertension". This term is used to indicate that we do not know the cause of why these patients have high blood pressure. The other group(10 to 15%) is said to have "secondary hypertension".

The causes for the high blood pressure in this group is disease of the kidneys (where the powerful renin-angiotensin mechanism is activated), pheochromocytoma, hyperthyroidism, hypothyroidism, primary aldosteronism, Cushing's syndrome, renovascular disease and coarctation of the aorta. Most of these conditions involve some form of powerful hormone changes or some structural changes in the kidneys. Several chronic kidney diseases are associated with hypertension such as glomerulonephritis, pyelonephritis, obstruction of the ureter from a kidney stone, congenital polycystic kidney disease and connective tissue disease affecting the kidneys.

Despite what I said above about primary (essential) hypertension quite a lot is known about this entity. Many authors now think that there is not one cause, but a combination of various factors that interact, all leading to hypertension. Such known factors are: stress leading to overstimulation of the sympathetic nervous system, sodium retention from overindulgence of salt and hereditary factors poorly understood so far. Absence of such substances as prostaglandins and others, which are found in kidney tissue and have a relaxing effect on arterial walls, can also lead to hypertension. This likely may be the major mechanism for hypertension in the case of chronic kidney diseases mentioned under secondary hypertension, where the tissue of the kidneys gets damaged. The lack of these arterial wall relaxing substances allows the other powerful artery constricting substances, renin and angiotensin as well as epinephrine and norepinephrine, to get the upper hand.

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Disclaimer

This outline is only a teaching aid to patients and should stimulate you to ask the right questions when seeing your doctor. However, the responsibility of treatment stays in the hands of your doctor and you.

References

1. "The sixth report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure ( JNC IV )" Arch Int Med 1997(157): 2413-2446.

2. JS Trilling et al. Arch Fam Med 2000 Sep/Oct (9): 794-801.

3. DJ Hyman et al. Arch Intern Med 2000 Aug 160(15): 2281-2286.

4. CP Tifft Curr Hypertens Rep 2000 Jun (3): 243-246.

5. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 199.

6. Noble: Textbook of Primary Care Medicine, 3rd ed.,2001, Mosby Inc.

7. Goroll: Primary Care Medicine, 4th ed., 2000, Lippincott Williams & Wilkins

Last Modified: Dec. 20. 2007