Secondary high blood pressure is caused by another condition. Prompt treatment is essential.
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.
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.
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.
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.
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.
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.
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.
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.
Treatment
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.
Last Updated: 10/06/2006
