What do I need to know about kidney health?

The kidneys are two bean-shaped organs. You have one on each side of the spine just below your ribcage. Each is about the size of a fist.

“Your kidneys help clean your blood out,” says Suzanne Martin, MD. She’s chief of nephrology at Reliant Medical Group, part of Optum, in Worcester, Massachusetts. “They make urine, which is basically a way to get rid of the toxins in your blood. And they remove extra fluid that you’re drinking throughout the day.”

The kidneys do even more to keep you healthy. They:

• Keep a healthy balance of water, salts and minerals in your blood
• Create hormones that help control blood pressure
• Make red blood cells
• Help keep bones strong and healthy

Blood flows into your kidneys through the renal artery. This artery branches off into smaller and smaller blood vessels. The blood then reaches the nephrons, which are filtering units. Each kidney has about a million nephrons.

Nephrons filter your blood and pull out waste and extra water, which become urine. The blood then exits the kidneys through the renal vein. Healthy kidneys filter about half a cup of blood a minute.²

Finally, the urine travels from your kidneys to your bladder through two thin tubes called ureters. Your kidneys, ureters, bladder and urethra make up your urinary tract.

“Usually, people only know that there’s trouble with their kidneys when they go to a doctor and get a blood test,” says Dr. Martin. “Typically, they have no symptoms of disease until the kidney function is really quite bad.”

Doctors use two tests to help determine how well your kidneys are working. If you have diabetes or high blood pressure, talk to your doctor. Ask about getting tested for kidney disease.

The two tests are:³

• A blood test that checks glomerular filtration rate. This can tell how well your kidneys are filtering blood.
   
• A urine test that checks for a protein called albumin. It can show any kidney damage. 

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1. Kidney infection. This happens when germs get into the kidneys, and cause:

• Fever, back pain or chills
• Frequent burning or pain while urinating
• Cloudy urine, or a change in urine color or odor
• Pus or blood in the urine

If you notice any of these signs, call your doctor right away. Also, reach out if you’re taking medication for a urinary tract infection but still don’t feel well. It could be a sign of a kidney infection.

2. Kidney stone. A kidney stone is generally a small rock or crystal made from chemicals in your urine. It usually forms inside your kidney. But it also can be found in a ureter. (That’s one of the tubes that carry urine from a kidney into your bladder.) The stone either stays in place or travels down into the ureter to your bladder and out of your body. When this happens, it can cause:

• Severe pain in your lower back
• Stomachache
• Blood in your urine
• Nausea or vomiting
• Fever and chills
• Urine that smells bad or looks cloudy

If you notice any of these symptoms, get in touch with your doctor.

3. Kidney cysts. These are fluid-filled sacs that are usually small, round or oval. You likely won’t know you have one unless you get tested for something else. Typically there are no symptoms, and they’re almost always harmless. But if you have many cysts, your doctor may test you for polycystic kidney disease (PKD). This is a more serious disorder that may require treatment.

4. Kidney cancer. This is among the 10 most common cancers in both men and women. About 79,000 new cases will be diagnosed in 2022.⁴

Kidney cancer is most often found in people ages 65 to 74. And about 13,920 people are expected to die from the disease in 2022. It’s very uncommon among people younger than 45.⁴

Early kidney cancers don’t usually have any symptoms. But larger tumors might. Many of the symptoms are often caused by diseases that aren’t cancer. Check with your doctor to figure out the possible cause. Symptoms of kidney cancer include:⁵

• Blood in the urine
• Low back pain on one side (not caused by an injury)
• A lump on the side or lower back
• Loss of appetite
• Weight loss not caused by dieting
• Fever that’s not caused by an infection and doesn’t go away
• Abnormally high or low red blood cell counts

Learn more about common kidney problems.

Chronic kidney disease (CKD) means that your kidneys are damaged. They don’t filter blood as well as they should. Over time, the kidneys stop working. It can be caused by other medical problems. The main risk factors for chronic kidney disease are:

• Diabetes
• High blood pressure
• Heart disease
• Obesity
• Family history of kidney disease
• Inherited kidney disorders
• Past damage to kidneys
• Aging

Diabetes and high blood pressure cause 2 out of 3 chronic kidney disease cases.⁶

Diabetes is the leading cause of chronic kidney disease.⁷ Diabetes happens when your blood sugar is too high. A hormone called insulin helps blood sugar get into your cells to give your body energy. When you have diabetes, your body might not make any insulin. Or it may not make enough or respond to it right way.

High blood sugar from diabetes can damage the blood vessels in the kidneys. When this happens, they don’t work as well.

High blood pressure is the second-most common cause of kidney failure in the U.S., after diabetes.⁸ Blood pressure is the force of blood pushing against the walls of your arteries. Arteries carry blood from your heart to other parts of your body.

Like high blood sugar, high blood pressure can also damage the blood vessels in your kidneys. If this happens, your kidneys won’t remove waste and extra fluid as well as they should. The extra fluid can then raise your blood pressure even more.

Many people with diabetes also have high blood pressure. Together, they’re dangerous for the kidneys.

Early chronic kidney disease doesn’t usually have any symptoms. As the disease advances, people may:⁹

• Fatigue
• Feel sick and have to vomit
• Itching
• Lose their appetite
• Metallic taste in the mouth
• Need to pee more, or need to pee less
• Have swelling in legs, feet or ankles
• Lose weight

If you have any of these symptoms, talk to your doctor.

No, but the earlier it’s identified, the earlier you can get treatment to slow the disease or keep it from getting worse. Early treatment often includes finding the cause, like diabetes or high blood pressure, and caring for it. If you have those medical problems, be sure to follow your doctor’s orders for taking your medications.

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Having kidney failure means that your kidneys don’t work well enough on their own to keep you alive.¹⁰ You’ll need either regular dialysis or a kidney transplant. Here’s what that means:

• Dialysis. Dialysis removes waste products and extra fluid from your blood. There are two types of dialysis:
  • Hemodialysis uses a machine to clean your blood. Typically, you have it done three to four times a week, at home or at a dialysis center.
     
  • Peritoneal dialysis cleans your blood inside your body. A few weeks before you start, a doctor will place a soft tube into your belly. Each day, you’ll connect it to a special bag of fluid that will flow into your belly. It will filter your blood over several hours, and then you’ll drain it out again. This is done several times a day or overnight.
     
• Kidney transplant. This is an operation that places a healthy kidney into your body from a dead or living donor. Medicines are needed to make sure your body doesn’t attack the new kidney.

All the usual habits that help keep you healthy overall can help your kidneys. Stay active and eat healthy meals. This can help you keep a healthy weight and improve diabetes and high blood pressure, says Dr. Martin. And if you smoke, quitting can help your kidneys, too. That’s because they’re packed with blood vessels that smoking can damage.

Here’s what else you can do:

• If you have diabetes, obesity, high blood pressure or heart disease, work with your doctor to care for them. “Taking care of your other medical problems is important,” says Dr. Martin.
   
• Get regular checkups with your doctor. “There are a lot of problems, like kidney disease, that start out quietly,” says Dr. Martin. “The only way to know that they’re there is by having regular follow-ups with your doctor.” 
   
• Have a family member with kidney failure, diabetes, high blood pressure or heart disease? Talk to you doctor about your health.
   
• Stay hydrated, but don’t overdo it. “Drink as you’re thirsty,” says Dr. Martin. “Your kidneys are pretty good at knowing what you need. They will help you hold on to more water when you need more water and help you get rid of it if you have too much.”
   
• Always talk to your doctor before taking any herb or supplements, say Dr. Martin.

1. National Kidney Foundation. Kidney disease: the basics. Accessed August 5, 2022.
2. National Institute of Diabetes and Digestive and Kidney Diseases. Your kidneys & how they work. Last reviewed June 2018. Accessed August 5, 2022.
3. National Institute of Diabetes and Digestive and Kidney Diseases. Chronic kidney disease tests & diagnosis. Accessed August 5, 2022.
4. American Cancer Society. Key statistics about kidney cancer. Last revised January 12, 2022. Accessed August 5, 2022.
5. American Cancer Society. Kidney cancer signs and symptoms. Last revised February 1, 2020. Accessed August 5, 2022.
6. National Kidney Foundation. Chronic kidney disease (CKD). Accessed August 5, 2022.
7. National Kidney Foundation. How your kidneys work. Accessed August 5, 2022.
8. National Kidney Foundation. High blood pressure and chronic kidney disease. Accessed August 5, 2022.
9. National Kidney Foundation. Preventing diabetic kidney disease: 10 answers to questions. Accessed August 5, 2022.
10. National Kidney Foundation. Kidney failure. Accessed August 5, 2022.

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