Your Kidneys and Your Health
Two small organs have a big impact on your health
The kidneys have a big job to do: Your whole body counts on these two bean-shaped organs—located below your ribs, on each side of your spine—to keep fluids flowing smoothly. They’re constantly filtering waste from the bloodstream to create urine. But diabetes can put your kidneys at risk. Elevated blood glucose levels can damage the blood vessels in the kidneys, making it harder for them to do their job. This is called chronic kidney disease due to diabetic nephropathy, and it can range from virtually undetectable to damage so severe that dialysis or a kidney transplant is required.
About a quarter of adults with diabetes have kidney disease, according to research published in June 2016 in JAMA. While many people with diabetes will eventually develop kidney disease, there are steps you can take that may prevent its onset or keep the disease from progressing.
Keep your glucose levels within your target range to reduce the risk of damage to the tiny blood vessels in your kidneys. High blood glucose is the leading cause of kidney disease.
Maintain healthy blood pressure levels to help prevent damage to blood vessels in the kidneys. High blood pressure is the No. 2 cause of kidney disease.
Follow a healthful eating plan as recommended by your dietitian, with an eye toward kidney health, to control both blood glucose and blood pressure. “If you eat a healthy diet low in salt and sugar, then your kidneys don’t have to excrete as much to keep your body in balance,” says Kelly Anne Hyndman, an assistant professor in cardio-renal physiology and medicine at the University of Alabama at Birmingham and spokesperson for the American Society of Nephrology. “In other words, your kidneys don’t have to work as hard.”
How can you know if you have kidney disease? Early stages have no symptoms, even as kidney function drops below 70 percent. “Most patients will not have any complaints and won’t realize they are having kidney problems,” says Mahnaz Mellati, MD, an endocrinologist at The Polyclinic in Seattle. As kidney disease worsens, you may feel fatigue, experience swelling in your hands and feet, or notice your urine has darkened. During end-stage kidney disease, you may experience anemia, bleeding or bruising, difficulty breathing, incontinence, itchiness, less urine production, nausea or loss of appetite, muscle cramps, swelling, or twitching.
There are two types of testing for kidney damage. A urine test—the albumin-to-creatinine ratio, or ACR—will spot early signs. Later signs of kidney disease, such as elevated creatinine levels, can be found in a blood test. Known as the estimated glomerular filtration rate, or eGFR, the test measures your overall kidney function. But this test won’t catch early signs of kidney disease—you need to lose about 50 percent of your kidney function before it shows an abnormality.
Getting a urine test for kidney disease? Go into it prepared. Exercise, infections, and even menstruation can skew your results. So don’t schedule the test when you’re sick or on your period. Stop exercising for 24 hours before the test. Conditions other than diabetic nephropathy may also cause elevated levels of protein or albumin in the urine, so a positive result doesn’t always mean that diabetic nephropathy is present.
The American Diabetes Association recommends that all people with type 2 diabetes get an annual urine albumin-to-creatinine test to check for kidney disease. People with type 1 diabetes are advised to get the same urine test every year after living with diabetes for five years. If you have high blood pressure, get tested annually, regardless of how long you’ve had diabetes.
That annual urine albumin-to-creatinine test is important, Mellati says. “I see people who come in for the first time when they have [early] chronic kidney disease. Patients go to the lab, they get the blood test, and they don’t get the urine [test],” she says. That means when kidney disease is in its early stages, both health providers and patients are unaware. “I think they don’t understand the importance of the urine. But [chronic kidney disease is] something, in many cases, we can prevent.”
So, you’ve been diagnosed with chronic kidney disease. Now what? Treatment options differ based on how advanced the disease is.
Diet. When looking to prevent kidney disease or slow its progression, people with diabetes must consider more than just carbohydrates in their diet. “In the early stages, it is important to choose the right type of protein,” says Melissa Prest, MS, RDN, CSR, LDN, president of the Illinois Academy of Nutrition and Dietetics and a board-certified specialist in renal nutrition. “Research conducted in persons with early stages of kidney disease has shown that adding more plant-based proteins, such as tofu and legumes, in place of protein from animal sources can help in delaying the progression of kidney disease.” People with kidney disease are still advised to eat close to the recommended daily allowance of protein, however.
If you have later-stage kidney disease, your health care team, including your dietitian, will encourage you to limit foods high in potassium, as the kidneys aren’t able to excrete excess potassium when affected by chronic kidney disease. Prest says you can swap potassium-rich foods, such as bananas, tomatoes, and potatoes, for lower-potassium foods such as apples and green beans.
You may also be advised to lower your salt intake. Doing so can help keep your blood pressure in check, which is important because high blood pressure can worsen kidney disease and increase the risk for heart attack and stroke. “Getting creative with herb seasonings in place of salt, making foods from scratch, and reducing packaged or restaurant foods can help to reduce sodium intake,” Prest says.
In later stages of kidney disease, the organs are not able to process phosphorus well. Too much phosphorus can pull calcium from your bones, weakening them and building calcium deposits in other parts of your body. “In any stage of chronic kidney disease, it’s smart to avoid colas and highly processed foods that have phosphorous additives,” says dietitian and diabetes educator Jill Weisenberger, MS, RDN, CDE. Those include cereal bars, flavored waters, nondairy creamers, and bottled coffee drinks. “Foods containing naturally occurring phosphorus are not usually restricted in early kidney disease, but they are often restricted in the later stages of chronic kidney disease.”
As with diabetes, kidney disease eating plans vary from person to person. “The appropriate dietary treatment for kidney disease is highly individualized and stage specific. That’s why each person must work with a registered dietitian nutritionist with experience in diabetes and kidney disease,” Weisenberger says.
Medication. The first step your doctor might take to help you manage kidney disease, and hopefully keep it from progressing, is to prescribe medication. ACE (angiotensin converting enzyme) inhibitors and ARBs (angiotensin receptor blockers) have been proven to slow down or even halt the progression of kidney disease by maintaining blood pressure control. But note: While ACE inhibitors and ARBs are effective when used separately, they may worsen kidney outcomes when used together.
Some diabetes medications appear to have favorable effects on the kidneys: The injectable liraglutide (Victoza) has been shown to improve kidney disease outcomes in people with type 2 diabetes. And the oral med empagliflozin (Jardiance) “has been proven to slow down kidney disease progression, in addition to having the same great benefits in the heart,” Mellati says. But this may only be helpful in people with early-stage kidney disease, as the drugs are processed by your kidneys. In later stages of the disease, Jardiance is not advised. Other diabetes medications may cause problems in later-stage kidney disease, too. Metformin, for instance, isn’t cleared by the kidneys in late-stage kidney disease and can cause lactic acidosis at high levels.
Dialysis. When kidney function falls to a critical level, dialysis becomes necessary. There are two types of dialysis: hemodialysis and peritoneal dialysis. During hemodialysis, blood is removed from the body via an access site in the arm and flows into a dialysis machine. The machine filters the blood—just as healthy kidneys do—then returns it to the body through the access site. Most people need hemodialysis three times a week for about three hours each session. This usually occurs at a dialysis center, but some hospitals can arrange for patients to do hemodialysis at home.
In peritoneal dialysis, the lining of the abdominal cavity, called the peritoneum, essentially becomes a filter for the blood. Here’s how it works: Using a permanent catheter placed into the abdominal cavity, patients fill the abdomen with fluid, which pulls waste products from the blood through the peritoneum. The fluid is later removed and discarded along with the filtered waste products. This is typically done three to four times per day, and some hospitals can provide patients with a special machine that can cycle fluid through the abdomen overnight, eliminating the need to exchange the fluid during the day.
Transplant. People on dialysis, or those who will require dialysis in the near future, may receive a transplant of a single kidney. The donated organ comes from either a deceased organ donor with healthy kidneys or from a living donor who can remain healthy with only one kidney.
The Eyes Have It
Diabetic retinopathy, damage to the small vessels in the eye that occurs in the presence of chronically elevated blood glucose, is present to some degree in almost all people with diabetic nephropathy. Kidney disease without retinopathy may be due to a cause other than diabetes. Talk to your doctor to find out what the cause may be.