Secondary Hypertension

In the United States, one in three adults has high blood pressure. In five to ten percent of these patients, there is an underlying, potentially correctable cause. This is secondary hypertension.

Many medications, both prescribed and over the counter, affect blood pressure as do substances such as alcohol, cocaine and amphetamines. Sometimes a trial period off the potentially offending medication is all that is needed to normalize blood pressure. Dietary causes of hypertension include excessive intake of sodium and licorice.

In young women, one of the more common (yet still rare) causes of secondary hypertension is fibromuscular dysplasia. For an unknown reason, the blood vessels to the kidneys become narrow, leading to less blood flow. As an act of self-preservation, the kidneys respond by sending messenger chemicals to raise blood pressure, hoping to increase blood flow. In older patients, blockage of the renal arteries may be due to atherosclerosis and will also result in systemic hypertension. In any suspected blockage of arteries to the kidneys, the initial diagnostic test is MRI.

Endocrine imbalances are extremely rare causes of secondary hypertension. These include pheochromocytoma, Cushing’s syndrome and hyperaldosteronism.  Much more common is thyroid dysfunction – both over and under active – which can cause hypertension.

When the blood pressure is high, one of the purposes of the physician’s assessment (history, physical examination, laboratory testing) is to exclude possible secondary causes. A patient’s response to medication must be monitored, since any patient with essential hypertension could develop secondary hypertension as well.

Am Fam Physician. 2010;82(12): 1471-1478.