One especially important cause of low blood pressure is orthostatic hypotension, which is sometimes referred to as postural hypotension. This happens when blood pressure drops rapidly during changes in body position—usually when changing from sitting to standing—inducing classic signs that the blood pressure is too low, like dizziness, blurry vision, and fainting.

^ Jump up to: a b c d e f Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo Jr. JL, Jones DW, Materson BJ, Oparil S, Wright Jr. JT, Roccella EJ, et al. (December 2003). "Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure". Hypertension. Joint National Committee On Prevention. 42 (6): 1206–52. doi:10.1161/01.HYP.0000107251.49515.c2. PMID 14656957. Archived from the original on 20 May 2012. Retrieved 1 January 2012.
^ Jump up to: a b c d e National High Blood Pressure Education Program Working Group on High Blood Pressure in Children and Adolescents (August 2004). "The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents". Pediatrics. 114 (2 Suppl 4th Report): 555–76. doi:10.1542/peds.114.2.S2.555. PMID 15286277.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Exercise also causes vasodilation, or the widening of blood vessels, which increases blood flow and decreases peripheral resistance — which, in healthy people, keeps the diastolic blood pressure from rising during activity. In fact, a diastolic blood pressure increasing greater than 10 mmHg during or after exercise represents an unstable form of hypertension, and may be associated with coronary artery disease, notes Len Kravitz, Ph.D. of the University of New Mexico.
2. Take the right nutrients. Talk with your chiropractor or other healthcare professional about the wide range of well-studied nutrients that, along with dietary and lifestyle modifications, can help normalize your blood pressure. One meta-analysis found magnesium supplements could lower blood pressure. Likewise, researchers find a small but significant decline in blood pressure for people with hypertension who use fish oil. (You can get all of fish oil’s benefits combined with anti-inflammatory flax oil and GLA in our Optimal Omega.) 
You will work with your provider to come up with a treatment plan. It may include only the lifestyle changes. These changes, such as heart-healthy eating and exercise, can be very effective. But sometimes the changes do not control or lower your high blood pressure. Then you may need to take medicine. There are different types of blood pressure medicines. Some people need to take more than one type.
Angiotensin receptor blockers prevent the actions of angiotensin II on the arteries. This means the arteries stay more open and blood pressure is lowered. ARBs can take a few weeks to work. Side effects can include dizziness, muscle cramps, insomnia, and elevated potassium levels. As with ACE inhibitors, women who are pregnant, planning to get pregnant, or breastfeeding should not take ARBs.
How the heart pumps blood into the arteries with enough force to push blood to the far reaches of each organ from the top of the head to the bottom of the feet. Blood pressure can be defined as the pressure of blood on the walls of the arteries as it circulates through the body. Blood pressure is highest as its leaves the heart through the aorta and gradually decreases as it enters smaller and smaller blood vessels (arteries, arterioles, and capillaries). Blood returns in the veins leading to the heart, aided by gravity and muscle contraction.
Unlike high blood pressure, low blood pressure is defined primarily by signs and symptoms of low blood flow and not by a specific blood pressure number. Some individuals routinely may have blood pressure numbers of 90/50 with no symptoms and therefore do not have low blood pressure. However, others who normally have higher blood pressures may develop symptoms of low blood pressure if their blood pressure drops to 100/60.
^ Ostchega Y, Dillon CF, Hughes JP, Carroll M, Yoon S (July 2007). "Trends in hypertension prevalence, awareness, treatment, and control in older U.S. adults: data from the National Health and Nutrition Examination Survey 1988 to 2004". Journal of the American Geriatrics Society. 55 (7): 1056–65. doi:10.1111/j.1532-5415.2007.01215.x. PMID 17608879.

Moderate or severe bleeding can quickly deplete an individual's body of blood, leading to low blood pressure or orthostatic hypotension. Bleeding can result from trauma, surgical complications, or from gastrointestinal abnormalities such as ulcers, tumors, or diverticulosis. Occasionally, the bleeding may be so severe and rapid (for example, bleeding from a ruptured aortic aneurysm) that it causes shock and death rapidly.
When blood pressure is measured, there are two numbers for each reading: for example, "120 over 80" is written as 120/80. This is because each heartbeat sends a pressure wave through the bloodstream. The higher number (systolic blood pressure) is the peak of the wave, when your heart contracts (the loud "thump" when you listen to your heartbeat). The lower number (diastolic blood pressure) is the lower "dip" or trough of the wave, when your heart relaxes.

When the systolic pressure drops below 90 mm Hg and the diastolic pressure falls below 60 mm Hg, this is categorized as low blood pressure. Some people may have low pressure all the time and this may be normal for them. If they do not experience any other signs or symptoms, medical treatment may not be necessary for them. Low blood pressure becomes a concern when it is accompanied by noticeable symptoms, such as dizziness, fainting and, in severe cases, shock. When this occurs, people should seek medical attention to determine if an underlying condition may be responsible for their hypotension.
A blood pressure reading measures both the systolic and diastolic forces, with the systolic pressure listed first. The numbers show your pressure in units of millimeters of mercury (mm Hg)—how high the pressure inside your arteries would be able to raise a column of mercury. For example, a reading of 120/80 mm Hg means a systolic pressure of 120 mm Hg and diastolic pressure of 80 mm Hg.
^ Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents, National Heart, Lung, and Blood Institute (Dec 2011). "Expert panel on integrated guidelines for cardiovascular health and risk reduction in children and adolescents: summary report". Pediatrics. 128 Suppl 5: S213–56. doi:10.1542/peds.2009-2107C. PMC 4536582. PMID 22084329.
Some people may ask why doctors are lowering the threshold for high blood pressure, when it was already difficult for many patients to achieve the previous blood pressure targets of below 140 mm Hg/90 mm Hg, said Dr. Pamela B. Morris, a preventive cardiologist and chairwoman of the ACC's Prevention of Cardiovascular Disease Leadership Council. However, Morris said that the guidelines were changed because "we now have more precise estimates of the risk of [high] blood pressures," and these new guidelines really communicate that risk to patients. So, just because it's going to be difficult for people to achieve, "I don't think it's a reason not to communicate the risk to patients, and to empower them to make appropriate lifestyle modifications," Morris told Live Science.

A 2015 review of several studies found that restoring blood vitamin D levels by using supplements (more than 1,000 IU per day) reduced blood pressure in hypertensive individuals when they had existing vitamin D deficiency.[167] The results also demonstrated a correlation of chronically low vitamin D levels with a higher chance of becoming hypertensive. Supplementation with vitamin D over 18 months in normotensive individuals with vitamin D deficiency did not significantly affect blood pressure.[167]

The value of routine screening for hypertension in children over the age of 3 years is debated.[90][91] In 2004 the National High Blood Pressure Education Program recommended that children aged 3 years and older have blood pressure measurement at least once at every health care visit[89] and the National Heart, Lung, and Blood Institute and American Academy of Pediatrics made a similar recommendation.[92] However, the American Academy of Family Physicians[93] supports the view of the U.S. Preventive Services Task Force that the available evidence is insufficient to determine the balance of benefits and harms of screening for hypertension in children and adolescents who do not have symptoms.[94]
Pulse pressure (the difference between systolic and diastolic blood pressure) is frequently increased in older people with hypertension. This can mean that systolic pressure is abnormally high, but diastolic pressure may be normal or low a condition termed isolated systolic hypertension.[59] The high pulse pressure in elderly people with hypertension or isolated systolic hypertension is explained by increased arterial stiffness, which typically accompanies aging and may be exacerbated by high blood pressure.[60]
For a normal reading, your blood pressure needs to show a top number (systolic pressure) that’s between 90 and less than 120 and a bottom number (diastolic pressure) that’s between 60 and less than 80. The American Heart Association (AHA) considers blood pressure to be within the normal range when both your systolic and diastolic numbers are in these ranges.
My BP gets taken once, when I arrive. Occasionally the top number is over 120. No health care provider has ever said anything to me about it. Only ONCE in the past 5 years, has any health care provider or assistant taken my BP again during the course of the exam to see if there’s been a change. So by your defintion, I’m getting poor clinical care. And that means what? As in, what will make that change? It sure won’t change for me raising the issue, I’m lucky if the provider even speaks to me. Providers spend more time staring at monitors then looking directly at the client/patient in the examination room.
Wear a blood pressure monitor. This monitor is attached to you. You will be asked to wear it for 24 hours. The monitor is usually programmed to take blood pressure readings every 15 to 30 minutes all day and night while you go about your normal activities. The doctor will evaluate the results. In some cases, home blood pressure monitors may also be used to evaluate the effectiveness of your treatment.

Because of the need for emergency care, it is important to recognize the early signs of malignant hypertension. The first giveaway is blood pressure of 180/120. You might have bleeding in the eyes due to rupture of the small blood vessels. Other malignant hypertension symptoms can include chest pain, dizziness, a headache, numbness in your extremities, and confusion.

7. Visit your chiropractor. A special chiropractic adjustment could significantly lower high blood pressure, a placebo-controlled study suggests. “This procedure has the effect of not one, but two blood–pressure medications given in combination,” study leader George Bakris, MD, told WebMD. Your chiropractor can create an effective protocol that helps normalize blood pressure without medication or other invasive procedures.

These guidelines help guide healthcare practices, and can be related to patient reimbursement and healthcare coverage. The tenth revision of the International Statistical Classification of Diseases and Related Health Problems, or ICD-10, is the set of codes used to designate specific health conditions and allow for reimbursement through health insurance programs.

Postural hypotension is considered to be a failure of a person's cardiovascular system or nervous system to react appropriately to sudden changes. Usually, when a person stands up, some of their blood pools in their lower extremities. If this remains uncorrected, it would cause the person's blood pressure to fall or decrease. A person's body usually compensates by sending messages to their heart to beat faster and to their blood vessels to constrict, offsetting the drop in blood pressure. If this does not happen, or does not happen quickly enough, postural hypotension is the result.
Excellent point! I can’t speak for anyone specifically, but I can say that generally, doctors make the worst patients. We don’t always follow the textbook guidelines nor abide by health recommendations. Then, there’s genetics, a pretty powerful force, and one over which we have little control. And, of course, there is just plain bad luck (or fate, finger of God, however you choose to describe it). So, many factors can come into play when a doctor gets diagnosed with what can otherwise be considered a preventable disease.
We tend not to think about our blood pressure — it’s a normal function of our heart working regularly. However, when blood pressure stays high over an extended period it means the heart is working harder than it should. Since hypertension usually doesn’t have symptoms, we don’t know what is happening unless we measure it. Accurately measuring blood pressure provides a glimpse into what’s happening inside our bodies without needing expensive diagnostic tests.