Renal Hypertension (High Blood Pressure)
Renal hypertension is high blood pressure caused by renal artery stenosis, a narrowing of the renal arteries that decreases blood flow to the kidneys. The blood-filtering function of the kidneys is mainly powered by the force of the blood pressure. Therefore, when blood flow decreases, the kidneys respond by producing a hormone (renin) that raises the blood pressure in an attempt to restore normal blood flow. However, because the low blood flow was caused by renal artery stenosis—and not low blood pressure—the renin raises the blood pressure too high, leading to renal hypertension.
Causes of Renal Hypertension
The most common cause of renal artery stenosis is hardening of the arteries (atherosclerosis). Atherosclerosis occurs when plaque—a mixture of fat, cholesterol, calcium and other substances—builds up inside the arteries, causing them to narrow and harden. Plaque can partially or fully block the flow of blood through an affected artery.
Less frequently, renal artery stenosis results from fibromuscular dysplasia (FMD), a condition that causes blood vessels throughout the body to become progressively twisted. Although the precise causes of FMD are unknown, some experts believe that genetics or hormones may play a role in its development.
Symptoms of Renal Hypertension
In many cases, renal hypertension does not produce noticeable symptoms. Some possible warning signs include:
- High blood pressure that cannot be controlled with medication
- High blood pressure at a relatively young age (under 30)
- Stable blood pressure that abruptly rises
- Narrowing of the arteries in the legs, brain, eyes or another part of the body
- Headaches and double vision
- Sudden fluid buildup in the lungs (pulmonary edema)
- Blood in the urine
Diagnosis of Renal Hypertension
High blood pressure is often detected during a routine medical checkup. If renal artery stenosis is suspected based on this or other symptoms, a physician will typically order one or more diagnostic tests, such as a:
- Duplex ultrasound
- Computerized tomographic angiography (CTA)
- Magnetic resonance angiogram (MRA)
- Catheter angiogram
Treatments for Renal Hypertension
Like primary hypertension—high blood pressure with no known cause—renal hypertension is often treated with medication, such as:
- Angiotensin-converting enzyme (ACE) inhibitors
- Angiotensin receptor blockers (ARBs)
If renal hypertension cannot be controlled with medication, other options such as angioplasty with stenting or renal bypass surgery may be considered. Because renal hypertension stresses the kidneys, it is a major cause of end-stage renal failure, particularly among older adults.
Tampa General Hospital ranks among the best hospitals in the nation for nephrology. Because we treat a high volume of patients with kidney disease—including many complex and challenging cases—we have acquired extensive experience, which translates to better outcomes and quality of life for our patients.