Blood pressure is a measurement that reflects the force of the blood on the walls of the arteries. It is expressed as the systolic pressure over the diastolic pressure (e.g., 120/80). Systolic pressure measures the force of the blood when the heart is actively pumping. Diastolic pressure measures the force of the blood when the heart is relaxed. Several factors can influence blood pressure and cause it to fluctuate.
Tobacco Use
Tobacco use is a major risk factor for high blood pressure, and it can cause blood pressure increases in those who usually have normal blood pressure. This is because nicotine makes the blood vessels narrower, forcing the heart to work harder to pump blood to the body's organs and tissues. This causes temporary increases in blood pressure levels.
Caffeine
Caffeine use can cause temporary increases in blood pressure, particularly if a person does not consume caffeine on a regular basis. Dr. Sheldon Sheps, a hypertension specialist at the Mayo Clinic, indicates that the caffeine in two to three cups of coffee can increase systolic blood pressure by 3 to 14 mm of mercury and diastolic blood pressure by 4 to 13 mm of mercury. People who don't drink caffeine on a regular basis may experience sharp spikes in blood pressure after consuming beverages containing caffeine.
Posture
Posture can affect blood pressure levels, with blood pressure generally increasing when a person moves from lying down to standing up. For consistent blood pressure measurements, patients usually have their blood pressure taken while sitting. If someone has hypertension and takes medications for the condition, a drop in blood pressure can be expected when standing up. These patients should have their blood pressure levels measured while sitting and again while standing so the difference in readings can be noted.
Diet
Diet plays a role in blood pressure levels. Meals high in sodium can cause increases in blood pressure because sodium causes fluid retention. When excess fluid is retained in the blood vessels, the heart has to work harder to pump blood. According to scientists from Rutgers University, sodium may also cause the arterioles to contract. This reduces the amount of blood that is returned to the heart and thereby increases blood pressure.
Physical Activity
Physical activity causes the heart rate to increase temporarily, but it can be very beneficial for reducing blood pressure levels. Exercise strengthens the heart muscle, making it easier for the heart to pump blood. This reduced effort leads to less force on the arteries, thus lowering blood pressure levels. The American Heart Association recommends 30 minutes of moderately intense exercise five days each week. This can help strengthen the heart and have a positive effect on blood pressure.
Drugs
Medications and illegal drugs can affect blood pressure levels. Drugs used to treat high blood pressure can cause low blood pressure if a higher dose than needed is used. Hormonal birth control pills, corticosteroids and decongestants are known to increase blood pressure as well. Illegal drugs like cocaine cause sharp increases in blood pressure because they cause constriction of the blood vessels, which makes the heart work harder to pump blood.
Medical Conditions
Kidney disease can lead to high blood pressure because the kidneys produce an enzyme (renin) that controls blood pressure. When the kidneys are damaged and renin production levels are abnormal, blood pressure cannot be controlled well. The adrenal glands produce hormones that affect the heart rate and blood pressure. When a tumor grows, it can cause the affected gland to produce too much of these hormones. This causes increased blood pressure levels and an increased heart rate.
