Secondary high blood pressure: When another condition causes hypertension

When something goes wrong in one part of your body, a ripple effect can create problems elsewhere — such as high blood pressure (hypertension). In fact, 5 percent to 10 percent of high blood pressure cases are caused by an underlying condition, according to the American Heart Association.

This type of high blood pressure, known as secondary hypertension, tends to appear suddenly. But there's good news. Proper treatment can often control or cure both the underlying condition and the high blood pressure, which reduces the risk of serious complications — including heart disease, kidney failure and stroke.

Here's a look at possible causes of secondary hypertension.

Diabetic nephropathy

Your kidneys contain millions of tiny blood vessels that filter waste from your blood and eliminate it in your urine. But diabetes can damage this delicate filtering system. In fact, diabetic nephropathy is the most common type of kidney failure — which is nearly always associated with high blood pressure. The high blood pressure can be treated with diet, exercise and medication. If your kidney function dips too low, you may need dialysis or a kidney transplant.

Polycystic kidney disease

In this inherited condition, cysts in the kidneys disrupt normal function and raise blood pressure. The high blood pressure can be treated with diet, exercise and medication. The polycystic disease may ultimately require dialysis or a kidney transplant.

Glomerular disease

Your kidneys filter waste and sodium using microscopic filters called glomeruli. Inflammation of these filters is called glomerulonephritis. If the inflamed glomeruli can't function normally, you may develop high blood pressure. The high blood pressure can be treated with diet, exercise and medication. Glomerulonephritis may be treated with medication, dialysis or a kidney transplant.

Hydronephrosis

In this condition, certain parts of one or both kidneys become plugged. This blocks urine flow and raises blood pressure. Some blockages resolve without treatment, but others require drainage or surgery. Once the blockage is removed, blood pressure often returns to normal.

Renovascular hypertension

This is a type of secondary hypertension caused by narrowing (stenosis) of one or both renal arteries. Renovascular hypertension can cause severe hypertension and irreversible kidney damage. It's often caused by the same type of fatty plaques that can damage your coronary arteries (atherosclerosis) or a condition in which the muscle and fibrous tissues of the renal artery wall thicken and harden into rings (fibromuscular dysplasia).

In mild cases, the high blood pressure may be treated with diet, exercise and medication while kidney function is simply monitored. In more severe cases, the doctor may open clogged arteries with a procedure known as angioplasty. Wire mesh tubes (stents) may be used to hold the arteries open. Another option is to surgically bypass blood flow around the affected arteries. Once blood flow to the kidneys improves, blood pressure usually returns to normal.

Renovascular hypertension

Renovascular hypertension

Kidney disease and high blood pressure can interact to create a variety of kidney problems, such as renovascular hypertension. The two main causes of this condition are atherosclerosis, which results in deposits of plaques in the arteries, and fibromuscular dysplasia, in which the muscle and fibrous tissues of the renal artery wall thicken and harden into rings.

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Cushing's syndrome

In this condition, corticosteroid medications, a pituitary tumor or other factors cause the adrenal glands to produce too much of the hormone cortisol. This raises blood pressure. Treatment may include surgery, radiation therapy or medication to return both cortisol and blood pressure to normal.

Aldosteronism

In this condition, a tumor in the adrenal gland, increased growth of normal cells or other factors cause the adrenal glands to release an excessive amount of the hormone aldosterone. This makes your kidneys retain salt and water and lose too much potassium, which raises blood pressure. Treatment may include medication to block the action of aldosterone, surgery to remove a tumor in the adrenal gland, and diet, exercise and medication to treat the high blood pressure.

Pheochromocytoma

This rare tumor in the adrenal gland increases production of the hormones adrenaline and noradrenaline, which can lead to persistent high blood pressure or marked fluctuations in blood pressure. Surgery to remove the tumor returns blood pressure to normal.

Hypothyroidism

This condition occurs when the thyroid gland doesn't produce enough thyroid hormone, which can cause high blood pressure. Hypothyroidism may have various causes, including inflammation, surgery, radiation treatment, certain medications or pituitary problems. Treatment with synthetic thyroid hormones usually returns blood pressure to normal.

Hyperthyroidism

This condition occurs when the thyroid gland produces too much thyroid hormone. This can increase the activity of epinephrine and norepinephrine, which can increase blood pressure. Treatment may include medication, radioactive iodine therapy or surgery, all of which can restore normal blood pressure.

Hyperparathyroidism

The parathyroid glands regulate levels of calcium and phosphorus in your body. If the glands secrete too much parathyroid hormone, the amount of calcium in your blood rises — which triggers a rise in blood pressure. Treatment is typically removal of the parathyroid glands, which returns blood pressure to normal.

Coarctation of the aorta

With this congenital defect of the body's main artery (aorta), a constriction (coarctation) in part of the aorta forces the heart to pump harder to get blood through the aorta and to the rest of your body. This, in turn, raises blood pressure — particularly in your arms. Surgery to repair the aorta can restore normal blood pressure.

Sleep apnea

In this condition, breathing repeatedly stops and starts during sleep. The repeated episodes of oxygen deprivation may damage the cellular lining of the blood vessel walls, which may deprive blood vessels of the elasticity they need to regulate blood pressure. Treating sleep apnea with a pressure mask, nasal devices, surgery, weight loss or other steps can help control the high blood pressure.

Obesity

As you gain weight, the amount of blood circulating through your body increases. This puts added pressure on your artery walls. In addition, excess weight often is associated with an increase in heart rate and a reduction in the capacity of your blood vessels to transport blood. All of these factors can increase blood pressure.

Preeclampsia

This common pregnancy complication, characterized by protein in the urine and elevated blood pressure, can develop after the 20th week of pregnancy. Left untreated, preeclampsia can lead to life-threatening complications for both mother and baby. The only cure for preeclampsia is delivery of the baby, which restores normal blood pressure.

Medications and supplements

Various prescription medications — from pain relievers to antidepressants and drugs used after organ transplants — can cause or aggravate high blood pressure. Birth control pills, decongestants and certain herbal supplements, including ginseng and St. John's wort, may have the same effect. Many illicit drugs, such as cocaine and methamphetamine, also increase blood pressure.

Treatment offers control

Once an underlying condition is effectively treated, secondary high blood pressure may decrease or even return to normal. Often, however, lifestyle changes — such as eating healthy foods, increasing physical activity and maintaining a healthy weight — remain an important part of blood pressure management. You may need to continue to take blood pressure medication as well.

Treatment can sometimes be complicated. But once you know you have high blood pressure, you can work with your doctor to control it.