The kidneys are amazing organs that work tirelessly to keep our bodies healthy. They are the main filtering system in the body, doing everything from filtering waste to maintaining electrolyte balance to producing hormones that regulate vital functions like blood pressure. Chronic kidney disease (CKD) is more common than imagined. The National Kidney Foundation estimates that 37 million American adults have chronic kidney disease, with many more at risk.

Let’s explore how the kidneys function, what chronic kidney disease is and how it's treated, and, most importantly, how to keep your kidneys healthy.

The kidneys are two bean-shaped organs located in the middle of the back, just below the rib cage, one on each side of the spine. They act as the body's primary filtration system, constantly filtering blood to remove excess water and waste products, which are then expelled from the body as urine.¹ Here are some interesting facts about the kidneys.

• Each kidney is about the size of a fist.¹
• According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the kidneys filter approximately 150 quarts of blood daily to produce about one to two quarts of urine.²
• Kidneys help maintain a healthy balance of electrolytes like sodium, potassium, and phosphates.³
• Kidneys also produce hormones that regulate blood pressure, stimulate red blood cell production, and contribute to bone health.²
• Each kidney contains about one million tiny filters called nephrons. Each nephron acts like a miniature coffee filter, retaining essential substances and returning them to the bloodstream while allowing waste products to pass through and exit the body through the urinary system.¹

The kidneys precisely regulate the levels of various minerals in the body, ensuring the optimal amount of substances like sodium and potassium are returned to the bloodstream while any excess is eliminated through urine.¹

Kidney disease occurs when the kidneys are damaged and can no longer filter blood effectively. This leads to a buildup of waste in the body, causing various health problems. Complications can include:⁴

• High blood pressure
• Anemia
• Weak bones
• Nerve damage
• Increased risk of cardiovascular disease

Often, kidney disease develops without noticeable symptoms. The NIDDK notes that severe kidney damage can lead to kidney failure, also known as end-stage renal disease (ESRD). ESRD means the kidneys have lost 85 to 90% of their function, requiring dialysis or a kidney transplant for survival.⁵ This underscores the importance of preventative measures to keep your kidneys healthy.

Acute kidney injury involves a sudden change in kidney function, often due to illness, injury, or certain medications.⁶

Chronic kidney disease is the most common form of kidney disease. It develops gradually, over many years, and is primarily caused by diabetes and high blood pressure.⁴

Several factors increase the risk of developing kidney disease:⁷

• Heart disease: A strong correlation exists between heart disease and kidney disease, although the exact reasons are still being researched.
• Diabetes: Diabetes, both type 1 and type 2, is the leading cause of kidney failure. High blood sugar levels overwork the kidneys, damaging their filtering ability. This type of kidney damage is called diabetic nephropathy.
• High blood pressure: High blood pressure (typically defined as greater than 130/80) is the second leading cause of kidney failure. It damages the delicate blood vessels in the kidneys, hindering their function.
• Family history: A family history of kidney disease increases an individual's risk.
• Ethnicity: African Americans, Hispanics, and Native Americans are at higher risk, likely due to higher rates of diabetes and high blood pressure within these groups.

The National Kidney Foundation attributes two-thirds of chronic kidney disease cases to diabetes and high blood pressure.⁷ Individuals at risk should discuss screening with their doctor.

Early detection of kidney disease is crucial, as it often presents no symptoms. Screening involves two main tests: a blood test to measure the glomerular filtration rate (GFR) and a urine test to detect the presence of albumin.⁸

• GFR indicates how well the kidneys are filtering. A GFR of 60 or higher is considered normal, while a GFR below 60 suggests kidney disease. A GFR of 15 or lower indicates kidney failure.
• Albumin is a protein that should not be present in urine. Its presence indicates kidney damage. A urine albumin level below 30 is normal, while levels above 30 are abnormal.

Individuals with diabetes should have their kidneys checked annually with both the GFR blood test and a urine albumin-creatinine ratio test. This is because albumin can leak into the urine even with a normal GFR, indicating early kidney disease.⁹ Kidney disease is progressive, meaning it worsens over time. While the damage is irreversible, early detection and treatment can effectively slow its progression.

If your primary care doctor suspects your kidneys aren’t functioning properly, the next step is to determine the state of your kidney function. Kidney disease is broken down into stages that reflect how much the disease has progressed by the time you’re diagnosed.¹⁰

• Stage 1: Kidney damage with normal kidney function (GFR 90 or higher).
• Stage 2: Kidney damage with mild loss of kidney function (GFR 60-89).
• Stage 3A: Mild to moderate loss of kidney function (GFR 45-59).
• Stage 3B: Moderate to severe loss of kidney function (GFR 30-44).
• Stage 4: Severe loss of kidney function (GFR 15-29).
• Stage 5: Kidney failure (ESRD) (GFR less than 15).

Several lifestyle modifications can help protect kidney health and slow the progression of kidney disease.

• Maintain a healthy weight: Being overweight strains the kidneys and increases the risk of high blood pressure and diabetes.³ Aim for gradual weight loss of about one pound per week.
• Avoid smoking: Smoking interferes with blood pressure medications and reduces blood flow to the kidneys. Explore smoking cessation resources like behavioral therapy, telephone services, and medications.³
• Limit alcohol: Excessive alcohol consumption impairs kidney function and can contribute to high blood pressure and liver disease. Individuals over 65 should limit their intake to no more than one drink per day.³
• Eat a kidney-friendly diet: A balanced diet can help protect kidneys, manage blood pressure and blood sugar, and prevent or delay complications. Consult a registered dietitian for personalized meal planning. Limiting sodium, protein, phosphorus, potassium, and fluid intake may be necessary, depending on the stage of kidney disease.¹¹
• Manage medications: Work with your healthcare provider to ensure medications are safe for your kidneys. Avoid NSAIDs like ibuprofen and naproxen, which can reduce blood flow to the kidneys.³ Always consult a pharmacist or provider about potential interactions between medications and supplements.
• Stay up to date on immunizations: Get annual flu, pneumonia, and shingles vaccines to protect your overall health.
• Monitor kidney health: Regularly check your GFR and urine albumin levels to track kidney function. Discuss any changes with your healthcare provider.³
• Manage underlying conditions: Control your blood pressure and blood sugar levels through lifestyle changes and manage medication prescribed by your doctor. A normal blood pressure reading is around 120/80 or below.¹³ If you have diabetes, aim for an A1C below 7%. If you are not diabetic, a target A1C is below 5.7%.¹²

By taking proactive steps to manage your health, you can significantly reduce your risk of developing kidney disease and slow its progression. Regular visits with your doctor are essential for developing a personalized plan to protect your kidney health.

Content contained on this page is for informational purposes only and does not constitute medical advice. Consult your health care provider before beginning any new fitness or dietary plan. References provided are for informational purposes only and do not constitute endorsement of any websites or other sources. Should you have any health-related questions, you should contact your health care provider.

• Your Kidneys & How They Work, National Institute of Diabetes and Digestive and Kidney Diseases, last accessed April 11, 2025, https://www.niddk.nih.gov/health-information/kidney-disease/kidneys-how-they-work.
• Are You "Kidney" Me?, Johns Hopkins Medicine, last accessed April 11, 2025, https://www.hopkinsmedicine.org/news/articles/2017/02/are-you-kidney-me.
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• Chronic Kidney Disease (CKD), National Kidney Foundation, last accessed April 11, 2025, https://www.kidney.org/kidney-topics/chronic-kidney-disease-ckd
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• Acute kidney injury, Mayo Clinic, last accessed April 11, 2025, https://www.mayoclinic.org/diseases-conditions/kidney-failure/symptoms-causes/syc-20369048.
• Kidney Disease: Fact Sheet, National Kidney Foundation, last accessed April 11, 2025, https://www.kidney.org/about/kidney-disease-fact-sheet.
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• Stages of kidney disease (CKD), American Kidney Fund, last accessed April 11, 2025, https://www.kidneyfund.org/all-about-kidneys/stages-kidney-disease.
• Kidney-friendly eating plan, American Kidney Fund, last accessed April 11, 2025, https://www.kidneyfund.org/living-kidney-disease/healthy-eating-activity/kidney-friendly-eating-plan.
• What Is the A1C Test?, American Diabetes Association, last accessed April 11, 2025, https://diabetes.org/about-diabetes/a1c.
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