There are a number of reasons for high systolic blood pressure. Some are temporary, like recent exposure to secondhand smoke or taking certain medications like decongestants. In other cases, systolic blood pressure is elevated chronically due to essential, or primary, hypertension. Secondary hypertension, due to an underlying disorder like kidney disease, can also cause high systolic blood pressure. According to the National Heart, Lung and Blood Institute, elevation of just the systolic blood pressure, a condition called isolated systolic hypertension, is the most common type of hypertension in people who are older than 60 years of age.
Isolated Systolic Hypertension
Approximately 65 percent of people with hypertension who are 60 years of age or older have isolated systolic hypertension. As we get older, systolic blood pressure, the top number of the blood pressure reading, tends to increase, while the diastolic blood pressure, the bottom number, tends to decrease. High systolic blood pressure is particularly important to address because it has been linked to an increased risk of stroke. Like high diastolic blood pressure, it is also a risk factor for heart attack, heart failure and hypertensive kidney disease.
Essential hypertension, also known as primary or idiopathic hypertension, is the cause of elevated blood pressure in an estimated 95 percent of people who have hypertension. Likewise, it is the most common cause of isolated systolic hypertension. In essential hypertension, there is no underlying medical condition to explain the elevated blood pressure. Besides older age, risk factors associated with essential hypertension include smoking, eating a high sodium diet, being overweight and living a sedentary lifestyle. Having a family history of essential hypertension also increases your risk.
Underlying Medical Conditions
In some cases, an underlying medical condition causes secondary hypertension and can lead to elevated systolic blood pressure. Chronic kidney disease causes hypertension because much of normal blood pressure regulation takes place in the kidney. In particular, a disorder called renal artery stenosis results in elevated blood pressure due to impaired blood flow to the kidneys. Coarctation of the aorta, a congenital condition that causes narrowing of the aorta, also leads to high blood pressure. Without surgical repair, coarctation causes blood to accumulate in the upper body, resulting in high blood pressure.
Endocrine disorders such as thyroid disease are also common sources of secondary hypertension. Primary aldosteronism, Cushing's syndrome and pheochromocytoma are other endocrine diseases that cause high blood pressure. These conditions all disrupt the hormonal balance that keeps blood pressure in a normal range. People with obstructive sleep apnea are also at increased risk of hypertension. Sleep apnea likely interferes with hormones that regulate blood pressure and also causes oxygen levels in the blood to fall during the night, further disrupting blood pressure control.
Medications and Substance Abuse
A number of prescription, over-the-counter and street drugs can also cause high systolic blood pressure. Some of the more common drugs that lead to high blood pressure include non-steroidal anti-inflammatory medications, like ibuprofen (Advil, Motrin) and naproxen (Aleve), decongestants such as pseudoephedrine (Sudafed) and birth control pills. Certain antidepressants, like fluoxetine (Prozac) and migraine medications such as sumatriptan (Imitrex) have also been linked to hypertension. Smoking and alcohol abuse lead to high blood pressure as well. Cocaine and other stimulants can cause severely elevated blood pressure that can be life-threatening.