Seven reasons to be good to your kidneys

They're trying to take good care of you.


Kidney disease is the 9th leading cause of death among all Americans and the 7th leading cause among adults 65 to 74 years of age. That’s one important reason to take good care of your kidneys. Here are seven more.

1. The kidneys keep blood pressure from getting too low.

If blood pressure starts to drop, the kidneys will try to raise it. In the short term, raising blood pressure is a good thing, because if it’s too low, oxygen can’t reach the brain. But in the long term, high pressure can damage the kidney’s blood vessels.

2. Kidneys maintain our watery internal environment.

If you drank a lot of water and your kidneys didn’t remove it from the blood, you would basically drown in fluid.

3. Kidneys help protect us against anemia.

They produce a hormone called erythropoietin that leads to the produc­tion of red blood cells.

4. Kidneys help protect our bones.

The kidneys have an enzyme that activates vitamin D. When you consume vitamin D or it’s made in the skin, it goes to the liver and then to the kidney, where it becomes the active form. The active form is important for absorbing calcium in the intestines, which helps to maintain bone health.

5. The kidneys remove toxins and other waste products.

The kidneys’ job to get rid of almost anything that you ingest that gets absorbed into the bloodstream and that the body doesn’t need—say, extra salt, calcium, or phosphorus. Main­taining that balance is critical. Gets rid of urea, uric acid, toxins, and other wastes via urine.

6. Kidneys maintain our acid-base balance.

They make sure that the body isn’t too acidic or two alkaline

7. Kidneys protect our hearts.

They maintain a balance of electrolytes (like potassium, sodium, and calcium), which is critical for heart rhythm.

What can harm the kidneys?

High blood pressure. It damages the small blood vessels of the kidney, which then damages the glomerulus—the basic filtering unit of the kidney. Each kidney can have up to a million glomeruli. Kidneys filter about 200 quarts of blood a day. So they are filled with blood vessels, and anything that impairs the blood flow through the kidney reduces the kidney’s ability to clean the blood.

Diabetes. It damages not only the small blood vessels in the glomerulus, but also something called the mesangium, which helps support the glomerulus.

Obesity. Obesity raises blood pressure and the risk of diabetes. Also, as people gain weight, the kidneys have to work harder.

You can imagine that the amount of waste products that need to get removed is far greater for a 250-pound person than for a 150-pound person, especially after we eat a large meal. So the kidney has to adapt. As people gain weight, the kidney can’t make more glomeruli, so the existing ones may start to enlarge and the kidney may start to filter blood at a greater rate, which puts an additional demand on the kidney. That may lead to damage and the eventual loss of some glomeruli. So the remaining glomeruli have to work that much harder, which leads to more lost glomeruli. It’s a vicious cycle.

Excess salt. It can raise blood pressure, and it’s possible that excess sodium itself may be harmful.

Too much protein? “I wouldn’t want someone who already has kidney disease on a diet that’s very high in animal protein,” says Harvard kidney expert Gary Curhan. “But there’s still disagreement about whether high-protein diets raise the risk of developing kidney disease. In moderate amounts, it’s proba­bly not harmful. I’d rather that people stop smoking, do more exercise, lose weight, and eat a healthy diet than worry only about how much protein they eat.”

Toxins in the environ­ment. Lead, mercury, cadmium.

Certain drugs. Excessive, long-term use of over-the-counter analgesics like acetaminophen and ibuprofen can also increase the risk of chronic kidney disease, possibly by raising blood pressure and/or by dam­aging the kidney directly. Studies about aspirin have been inconsistent. If you take those analgesics on a reg­ular basis, ask your healthcare provider about alternatives. Just because these drugs are available over the counter doesn’t mean they’re safe.

More about our kidneys, from Gary Curhan.

Q: Is exercise good for kidneys?

A: “Exercise helps keep blood vessels healthy, lowers blood pressure, reduces the risk of diabetes, and helps people lose weight. So even without conclusive evidence, I would encourage people to be active to protect their kidneys,” says Curhan.

Q: Does early kidney disease have symptoms?

A: “Most of the time there are none. It’s like high blood pressure. The best way to get people diagnosed is by screening people at higher risk for developing kidney disease—those with diabetes or hypertension. We do a blood test for creatinine and check urine for protein. But there’s not enough convincing data to demonstrate that we should screen everyone.”

Q: Can we protect our kidneys?

A: “Yes. Many of the conditions that affect the kidney are preventable. The message is quite similar to what you would do to protect your heart. Lowering your cardiovascular risk goes a long way toward protecting your kidneys. And kidneys are another reason for peo­ple to try to control their blood pressure and blood sugar if they have high levels. The best thing would be to avoid devel­oping high blood pressure and diabetes in the first place.”

Gary Curhan is a nephrologist and a professor of medicine at Harvard Medical School and professor of epidemiology at the Harvard School of Public Health. His research has focused on the causes of kidney stones.

This post was originally published in 2015 and is updated as needed.

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