African Americans & Health: Focus on Chronic Kidney Disease (Part 3 in a Series)

True or false: Chronic kidney disease, or CKD, causes more deaths than breast cancer or prostate cancer.

The answer: True! A largely under-recognized public health issue, CKD is the ninth leading cause of death in the U.S. today.

And hardest-hit by chronic kidney issues? The African American community. Although African Americans constitute 13% of the population, they suffer more than triple the rate of kidney failure of Caucasians. Over ⅓ of patients receiving kidney dialysis in this country are African American. And this demographic is 3½ times more likely to experience end-stage renal disease, compared to non-Hispanic whites.

The numbers are certainly alarming. But, before we explore some potential reasons for them, let’s take a quick look at how kidneys function—and malfunction.

Your Personal Waste Disposal Unit

Kidneys are the body’s personal recycling bin. They remove waste, regulate fluid balance and ensure electrolyte and mineral balance. The kidneys also control your blood pressure and regulate how many new red blood cells your body makes.

With every beat of your heart, over 20% of the blood that’s pumped goes directly to your kidneys, where millions of tiny filtering units—or glomeruli—filter blood, extracting plasma. Then the rest of the kidney processes what has been filtered to return what is needed to your body while excreting what you don’t need.

Symptoms and Risk Factors

Like high blood pressure, CKD can be a silent threat. When the kidneys are damaged or fail to function properly, a patient may initially experience no symptoms, until damage gradually becomes more severe.

Some possible risk factors for kidney disease may include:

• High blood pressure (hypertension)
• Diabetes
• Pre-diabetes
• Heart disease or heart failure
• A family history of CKD, kidney failure, or dialysis
• Overweight or obesity

For most patients with high blood pressure or diabetes, concurrent kidney disease happens very gradually, over time.  An occasional exception might be malignant hypertension, when an unusually radical spike in blood pressure could lead to kidney failure, as well as stroke or heart attack.

The Five Stages of CKD

For most people, kidney failure occurs after years of having CKD. Kidney damage progresses through five stages.

In the earliest stages, the kidneys begin to leak proteins such as albumin into the urine. This is called proteinuria, an excess of protein in the urine. Uncontrolled over time, this excess can lead to kidney failure, when the kidneys no longer function well enough to eliminate fluid and electrolytes, keep the body clean, and prevent illness caused by high levels of waste products. At this stage, dialysis or a kidney transplant is likely required to maintain health.

The Glomerular Filtration Rate (GFR) checks how much blood passes through the glomeruli—those tiny filtering units—per minute. As the filtration rate declines, the kidneys become more and more compromised. The five stages, as defined by the National Kidney Foundation, look like this:

• Stage 1—Normal or high GFR (GFR >90 mL/min)
• Stage 2—Mild CKD (GFR = 60–89 mL/min)
• Stage 3A—Moderate CKD (GFR = 45–59 mL/min)
• Stage 3B—Moderate CKD (GFR = 30–44 mL/min)
• Stage 4—Severe CKD (GFR = 15–29 mL/min)
• Stage 5—End Stage Renal Disease/Stage 5 CKD (GFR <15 mL/min)

Of course, as nephrologists, our mission is to strive to keep patients from reaching stage 5.  Perhaps we’re able to make an early diagnosis by discovering a little protein in their urine. Or we watch carefully to assure that their blood pressure doesn’t get too high or that their diabetes is not out of control. As we try to manage these symptoms through stages 2, 3, and 4, we use medicines to reduce stress on the kidneys so they don’t struggle to work so hard. With this approach, we’re typically successful in slowing the rate at which kidneys fail.

Considerations for African Americans

We look at several factors that seem to spur higher levels of kidney disease within our African American population:

• Biological Factors
  • Prevalence of diabetes: The higher incidence of diabetes in our African American community translates to a higher risk for the kidneys. Diabetes occurs when sugar levels become too high in the blood. Glucose can infiltrate cells without insulin receptors—in the back of the eye, in the retina, within the peripheral nervous system, and in some of the filtering units of the kidney—and cause damage. The damage stimulates more scar tissue, which causes reduced kidney function and potentially more protein leakage. This, in turn, leads to even greater scarring and damage to the kidneys, in a hazardous cycle.
  • Prevalence of high blood pressure: Genetic factors certainly play a role in the higher incidence of high blood pressure in African Americans. And a high-salt diet can make it worse. High blood pressure can also contribute to hypertensive nephrosclerosis—scarring the glomeruli and diminishing their functionality.
• Genetic Factors
  Approximately 15% of the African American population has two copies of an abnormal gene called APOL1. Risk of CKD increases markedly for people who have two copies of APOL1 in combination with another risk factor, such as diabetes or hypertension.
• Other Factors
  Taking non-steroidal anti-inflammatory drugs (NSAIDs), such as Aleve® (naproxen), Motrin® (ibuprofen), and Advil® (ibuprofen), can potentially inflict damage to the kidneys. In high doses, these medications may interfere with a patient’s blood pressure medicines and cause a rise in blood pressure. Tylenol®—which is acetaminophen, not an NSAID—can be safely taken by people with kidney disease.
  Kidney function can also be negatively impacted by infections, severe dehydration, or acute damage due to heart disease.

Testing for CKD

Two simple tests provide a primary care doctor with the basic information they need to diagnose a patient’s kidney health.

• The Estimated Glomerular Filtration Rate (eGFR) test measures the patient’s blood creatinine level. Based on age and other factors combined with the patient’s creatinine level, the test delivers an estimated filtration rate. If your eGFR is less than 60%—less than 60 mLs per minute—you would likely be referred to a kidney specialist.
• An ACR urine test will measure your albumin-to-creatinine ratio and indicate any noteworthy increase in the level of urine albumin (microalbuminuria). Kidneys which are a little leakier of protein than normal are considered under stress, and an ACR in the high range will likely prompt a referral to a kidney specialist.

Prevention and Treatment

Kidney disease is rarely painful and can easily hide until it’s progressed to a more serious stage.

As a first line of defense, maintaining a healthy weight, following a low-salt diet, and getting regular exercise can go a long way to keep kidneys healthy. Individuals with kidney disease in their family should see their primary care doctor for blood pressure, pre-diabetes and diabetes screenings, and ACR testing to ensure urine free from microalbuminuria.

Here at MedStar Washington Hospital Center, our specialists check for complications from high blood pressure and long-term diabetes. For example, we may request results of a recent eye exam or call for a new one, or we may discuss with patients possible nerve damage from their diabetes.

Then, treatment typically starts with medications to help the kidneys leak less albumin and reduce the overall stress on the kidney. We make sure the patient’s diabetes is controlled and blood pressure is low, and we counsel on diet.

For example, in a hypothetical scenario where a patient has a slightly elevated ACR, but kidney function is normal and blood pressure is a little high, we might treat the blood pressure and work with the patient to lower it, in turn reducing the ACR.

Occasionally, we might explore for a possible structural issue, such as a kidney stone or enlarged prostate that’s blocking flow from the kidneys.

Some Tips for Everyone

My general advice to stay kidney-healthy is to listen to your body and drink water when it tells you to replenish fluids. The amount of water to drink daily is different for everyone, so let your own thirst be a guide. If you have kidney stones, keep drinking more than two quarts of liquid every single day.

Also, try to reduce sodium. Consume less animal protein, particularly red meat. Schedule a checkup immediately if your urine contains blood, or if the urine becomes very foamy, indicating the presence of excess protein. If your family has a history of kidney ailments, you’ll want to discuss that with your primary care provider.

And don’t let COVID-19 stop you from visiting one of our specialists. Our staff at the Hospital Center is making very effective use of the telehealth option. Of course, for people with advanced kidney disease, there’s no substitute for listening to the heart and lungs, and we schedule those patients for a physical examination.