What causes the lower bp number to be high

What causes high blood pressure?

Blood pressure is the measure of the force of blood pushing against blood vessel walls. The heart pumps blood into blood vessels, which carry the blood throughout the body. High blood pressure, also called hypertension, is dangerous because it makes the heart work harder to pump blood out to the body and contributes to hardening of the arteries, or atherosclerosis, to stroke, kidney disease, and to heart failure.

What Is "Normal" Blood Pressure?

A blood pressure reading is written like this: 120/80. It's read as "120 over 80." The top number is called the systolic, and bottom number is called the diastolic. The ranges are:

• Normal: Less than 120 over 80 (120/80)
• Elevated: 120-129/less than 80
• Stage 1 high blood pressure: 130-139/80-89
• Stage 2 high blood pressure: 140 and above/90 and above
• Hypertension crisis: higher than 180/higher than 120 -- See a doctor right away

If your blood pressure is above the normal range, talk to your doctor about how to lower it.

What causes high blood pressure?

The exact causes of high blood pressure are not known, but several things may play a role, including:

• Smoking
• Being overweight or obese
• Lack of physical activity
• Too much salt in the diet
• Too much alcohol consumption (more than 1 to 2 drinks per day)
• Stress
• Older age
• Genetics
• Family history of high blood pressure
• Chronic kidney disease
• Adrenal and thyroid disorders
• Sleep apnea

Essential Hypertension

In as many as 95% of high blood pressure cases in the U.S., the underlying cause can't be found. This type of high blood pressure is called "essential hypertension."

Though essential hypertension remains somewhat mysterious, it has been linked to certain risk factors. High blood pressure tends to run in families and is more likely to affect men than women. Age and race also play a role. In the United States, blacks are twice as likely as whites to have high blood pressure, although the gap begins to narrow around age 44. After age 65, black women have the highest incidence of high blood pressure.

Essential hypertension is also greatly influenced by diet and lifestyle. The link between salt and high blood pressure is especially compelling. People living on the northern islands of Japan eat more salt per capita than anyone else in the world and have the highest incidence of essential hypertension. 

Most people with high blood pressure are "salt sensitive," meaning that anything more than the minimal bodily need for salt is too much for them and increases their blood pressure. Other factors that can raise the risk of having essential hypertension include obesity; diabetes; stress; insufficient intake of potassium, calcium, and magnesium; lack of physical activity; and chronic alcohol consumption.

Secondary Hypertension

When a direct cause for high blood pressure can be identified, the condition is described as secondary hypertension. Among the known causes of secondary hypertension, kidney disease ranks highest. Hypertension can also be triggered by tumors or other abnormalities that cause the adrenal glands (small glands that sit atop the kidneys) to secrete excess amounts of the hormones that elevate blood pressure. Birth control pills -- specifically those containing estrogen -- and pregnancy can boost blood pressure, as can medications that constrict blood vessels.

Who Is More Likely to Develop High Blood Pressure?

• People with family members who have high blood pressure
• Smokers
• African-Americans
• Pregnant women
• Women who take birth control pills
• People over the age of 35
• People who are overweight or obese
• People who are not active
• People who drink alcohol excessively
• People who eat too many fatty foods or foods with too much salt
• People who have sleep apnea

THURSDAY, July 18, 2019 (HealthDay News) -- When it comes to blood pressure readings, the "top" number seems to grab all the attention.

But a large, new study confirms that both numbers are, in fact, critical in determining the risk of heart attack and stroke.

Blood pressure measurements are given as a "top" and "bottom" number. The first reflects systolic blood pressure, the amount of pressure in the arteries as the heart contracts. The second reflects diastolic blood pressure, the pressure in the arteries between heart muscle contractions.

For years, systolic blood pressure has been seen as the one that really matters. That's based on studies -- including the famous Framingham Heart Study -- showing that high systolic blood pressure is a stronger predictor of heart disease and stroke.

At the same time, though, doctors measure both systolic and diastolic blood pressure, and treatment guidelines are based on both. So just how important is that diastolic number?

"The idea behind this new study was to address the confusion," said lead researcher Dr. Alexander Flint, an investigator with Kaiser Permanente Northern California's division of research.

Using medical records from 1.3 million patients, his team confirmed that, yes, high systolic blood pressure was a stronger risk factor for heart attack and stroke. But those risks also climbed in tandem with diastolic pressure; and people with normal systolic readings were still at risk if their diastolic pressure was high.

"There's been a common belief that systolic blood pressure is the only one that matters," Flint said. "But diastolic definitely matters."

He and his colleagues reported the findings in the July 18 issue of the New England Journal of Medicine.

The definition of high blood pressure has gotten a revamp in recent years. Guidelines issued in 2017 by the American College of Cardiology (ACC) and other heart groups lowered the  threshold for diagnosing the condition -- from the traditional 140/90 mm Hg to 130/80.

The fact that treatment guidelines include a diastolic pressure threshold implies that it's important. And indeed it is, said Dr. Karol Watson, a member of the ACC's prevention section and leadership council.

In fact, she said, doctors once thought that diastolic blood pressure was the more important one -- based on research at the time. Then came the studies showing that systolic pressure was generally a better predictor of people's risk of heart disease and stroke.

In addition, Watson said, high systolic blood pressure is more prevalent, because of natural changes in blood pressure as people age.

"As we get older, systolic blood pressure keeps marching up," she explained. Diastolic blood pressure, on the other hand, generally peaks when people are in their 40s to 60s -- and then it declines.

But it's clear, Watson said, that while systolic and diastolic blood pressure are different, they both deserve attention.

In the latest study, cardiovascular risks rose with each "unit increase" in systolic pressure above 140, by about 18% on average. Meanwhile, each increase in diastolic blood pressure above 90 was tied to a 6% increase in heart disease and stroke risk.

The researchers saw a similar pattern when they looked at blood pressure increases above the 130/80 threshold. That, Flint said, supports the 2017 guideline shift.

The findings are based on over 1.3 million patients in the Kaiser Permanente health system who had roughly 36.8 million blood pressure readings taken from 2007 through 2016. Over eight years, more than 44,000 patients had a heart attack or stroke.

According to Flint, it's the largest study of its kind to date.

The bottom line for patients, Watson said, is that they should care about both blood pressure numbers. In her experience, she noted, patients often point to the number that's in the normal range and say, "But look how good this is."

Flint agreed, saying that no one should "ignore" the diastolic number. "It's important not only in blood pressure treatment, but on the side of diagnosis, too," he said.