Learn About Kidney Disease Signs and Symptoms

Understanding Kidney Disease: What Kidneys Do and Why They Matter

Your kidneys are two bean-shaped organs, each about the size of your fist, located on either side of your spine below the rib cage. Despite their small size, kidneys perform critical functions that keep your body healthy. Most people know kidneys filter waste from blood to create urine, but their work goes far beyond that single task.

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Kidneys filter about 120 to 150 quarts of blood daily to produce roughly 1 to 2 quarts of urine. This filtering process removes excess water, salts, and other waste products that your body doesn't need. But kidneys also regulate blood pressure by controlling fluid and salt balance, produce hormones that help create red blood cells, activate vitamin D to keep bones strong, and maintain the right balance of chemicals in your blood.

When kidneys function normally, they work quietly in the background. You might not think about them at all. However, kidney disease develops when kidneys lose their ability to filter waste properly. This happens gradually in most cases. According to the National Kidney Foundation, about 1 in 7 American adults—roughly 37 million people—have chronic kidney disease. Many don't know they have it because early stages often show no noticeable symptoms.

There are five stages of chronic kidney disease, numbered 1 through 5. Stage 1 means mild kidney damage with normal kidney function. Stage 5 is kidney failure, where kidneys work at less than 10 percent of normal function. The earlier kidney disease is caught, the better the outcomes tend to be. Understanding how kidneys work helps explain why recognizing warning signs matters so much.

Takeaway: Healthy kidneys perform multiple essential functions beyond filtering waste. Since early kidney disease often has no symptoms, learning what to watch for gives you the chance to catch problems when they're easier to manage.

Early Warning Signs You Might Have Kidney Disease

Early kidney disease frequently produces no symptoms at all. This silent progression is one reason why kidney disease is sometimes called a "silent killer." Some people discover they have kidney disease only when a doctor runs routine blood work or urine tests for other reasons. However, as kidney function declines, certain warning signs may appear.

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One of the earliest detectable signs is blood or protein in your urine, which you typically cannot see or feel. A simple urine test can reveal this. Another early indicator might be high blood pressure that's difficult to control, even with medication. Conversely, if your blood pressure suddenly drops or becomes hard to manage in new ways, this could signal kidney changes.

Fatigue and weakness often accompany early kidney disease. This happens because damaged kidneys produce less erythropoietin, a hormone that signals your bone marrow to make red blood cells. With fewer red blood cells, your blood carries less oxygen to tissues, leaving you feeling tired. This fatigue typically worsens as kidney function declines. You might notice you need more rest than usual or feel worn out after activities you once handled easily.

Some people in early stages experience swelling in their ankles, feet, or face. This occurs when damaged kidneys cannot regulate fluid balance properly, causing fluid to accumulate in tissues. The swelling might be worse in the morning or after standing for long periods. Puffiness around the eyes is sometimes an early sign.

Changes in urination patterns can indicate kidney problems. This might mean needing to urinate more frequently, especially at night, or noticing changes in urine color or appearance. Some people produce less urine than normal. Others experience foamy or bubbly urine, which suggests protein is leaking into the urine.

Takeaway: Early kidney disease signs are often subtle and easy to overlook. Regular health checkups with blood and urine tests remain the most reliable way to catch kidney problems before symptoms develop.

Recognizing Advanced Symptoms of Kidney Disease

As kidney disease progresses to advanced stages, symptoms become more noticeable and affect daily life. By stage 4 or 5, when kidney function drops below 30 percent, most people experience multiple symptoms. Recognizing these signs matters because they indicate your kidneys need urgent medical attention.

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Severe fatigue and weakness intensify significantly in advanced kidney disease. This goes beyond normal tiredness. People often describe feeling completely drained, struggling to work, or finding it difficult to care for themselves or their families. This severe fatigue directly connects to anemia—the shortage of red blood cells—and the buildup of waste products in the bloodstream.

Nausea and loss of appetite commonly occur when kidney function falls significantly. Waste products accumulate in the blood, causing a condition called uremia. This buildup affects the stomach and digestive system, making food unappealing or causing persistent nausea. Some people develop a metallic taste in their mouth. Unintentional weight loss often follows because people eat less due to poor appetite.

Itching becomes a frustrating symptom for many people with advanced kidney disease. The itching is often intense and widespread, affecting various parts of the body. Scientists believe this happens because kidneys cannot remove certain waste products that build up in the skin. Scratching can lead to skin infections, adding another complication.

Bone and joint pain may develop because damaged kidneys cannot properly activate vitamin D, which your body needs to absorb calcium. Without adequate calcium, bones weaken and become painful. Some people experience muscle cramps, particularly in the legs, as kidney disease progresses.

Brain fog and difficulty concentrating sometimes accompany advanced kidney disease. The buildup of waste in the bloodstream affects cognitive function. Some people report memory problems or feeling confused. High blood pressure that develops or worsens with kidney disease can also contribute to these symptoms.

Takeaway: Advanced kidney disease symptoms significantly impact quality of life. If you experience multiple symptoms like severe fatigue, persistent nausea, or unexplained itching, mention them to your doctor—these warrant testing to check your kidney function.

Risk Factors That Increase Your Chances of Kidney Disease

Certain conditions and lifestyle factors substantially increase the likelihood of developing kidney disease. Understanding your personal risk helps you and your doctor monitor your health more carefully. The two leading causes of kidney disease in the United States are diabetes and high blood pressure, together accounting for about two-thirds of all kidney disease cases.

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Diabetes damages blood vessels in the kidneys. When blood sugar stays too high for years, it harms the delicate filtering units called nephrons. About 1 in 4 people with diabetes develop chronic kidney disease. Type 2 diabetes is more common than Type 1, so it accounts for more kidney disease cases overall, but both types carry significant risk.

High blood pressure damages kidney blood vessels over time. When pressure inside kidney blood vessels is consistently too high, it scars and weakens the vessels' ability to filter properly. Interestingly, kidney disease and high blood pressure create a dangerous cycle: damaged kidneys cannot regulate blood pressure well, which causes higher pressure, which damages kidneys further.

Age increases kidney disease risk. People over 60 have a higher prevalence of chronic kidney disease, though the disease can develop at any age. Family history matters significantly—if relatives had kidney disease, kidney failure, or required dialysis, your risk increases. African Americans, Hispanic Americans, Native Americans, Asian Americans, and Pacific Islander Americans have higher rates of kidney disease than white Americans, likely due to combinations of genetic factors, higher rates of diabetes and high blood pressure, and differences in access to healthcare.

Obesity increases kidney disease risk, partly through its connection to diabetes and high blood pressure. Smoking damages blood vessels throughout the body, including those in the kidneys. Heavy alcohol use strains the kidneys and can contribute to high blood pressure. Recurrent kidney infections scar kidney tissue over time. Autoimmune diseases like lupus can attack the kidneys directly.

Certain medications, when used long-term or in high doses, can damage kidneys. These include some pain relievers, particularly nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and naproxen. Some blood pressure medications, antibiotics, and contrast dyes used in medical imaging can also affect kidney function in susceptible people.

Takeaway: If you have diabetes, high blood pressure, a family history of kidney disease, or belong to a higher-risk ethnic group, discuss regular kidney function screening with your doctor. Catching kidney