The kidneys play an important role in maintaining blood pressure as well as the amount of fluid, protein and wastes in the blood. When the kidneys are damaged, they cannot perform these functions properly. High blood pressure coupled with protein in the urine usually indicates some degree of kidney disease or damage.
High Blood Pressure
According to the National Kidney and Urologic Diseases Information Clearinghouse, high blood pressure is one of the top causes of kidney disease. When you have high blood pressure, your heart has to work harder to pump blood to meet the needs of your body. Over time, your blood vessels, including the blood vessels of the kidneys, become damaged. When the kidney's blood vessels are damaged, they can no longer remove wastes and extra fluid from the blood effectively.
Secondary Hypertension
When the kidneys cannot remove excess fluid from your blood, the fluid leaves your blood vessels through a process called osmosis, and leaks into open spaces in your tissues. This leads to a type of swelling referred to as edema. The extra fluid also increases your blood volume, which further increases your blood pressure, putting even more stress on the kidneys. The increase in blood pressure caused by kidney disease is referred to as secondary hypertension.
Protein in the Urine
Kidney disease is also characterized by an abnormal amount of protein in the urine. Normally, the kidneys do not filter important proteins, like albumin, out of the blood. When you have kidney disease, the blood vessels in your kidneys, called glomeruli, allow proteins to pass from the blood into your urine. As a result, the proteins become measurable in your urine.
In the early stages of kidney damage, only a small amount of protein is able to pass through into the urine. This is referred to as microalbuminuria. As kidney disease progresses, more proteins are allowed to pass through to the urine, a condition referred to as proteinuria.
Tips to Control Blood Pressure
If you have high blood pressure and kidney disease, it is especially important to make lifestyle changes to lower your blood pressure in order to prevent further kidney damage. The National Heart, Lung and Blood Institute recommends five key changes. The first is to maintain a healthy weight. It is also important to incorporate plenty of fruits, vegetables, whole grains and low-fat dairy into your diet. Restrict sodium intake to less than 2,000mg per day. Avoiding processed foods, canned foods and eating out can help reduce your total sodium intake. Getting regular exercise is another important aspect of maintaining your weight and lowering your blood pressure. Aim for at least 30 minutes of exercise on most days of the week.
It is also important to avoid or limit alcohol. Men should consume no more than two drinks per day, whereas women should limit alcohol intake to one drink daily.
References
- National Kidney and Urologic Diseases Information Clearinghouse; High Blood Pressure and Kidney Disease; July 2008
- National Kidney Foundation: How Your Kidneys Work
- National Kidney and Urologic Diseases Information Clearinghouse; Proteinuria; March 2009
- MayoClinic.com; Secondary hypertension; March 22, 2011
