Chronic renal disease, more commonly called chronic kidney disease (CKD), is a long-term condition in which the kidneys gradually lose their ability to filter waste and excess fluid from the blood. It affects roughly 788 million adults worldwide, with a global prevalence of about 14.2%. The condition progresses through five stages, and most people feel no symptoms until the damage is already advanced.
How CKD Develops
Your kidneys contain roughly one million tiny filtering units called nephrons. When disease or injury destroys some of these nephrons, the surviving ones compensate by working harder, filtering more blood at higher pressure than they were designed to handle. This overwork damages the delicate capillaries inside those remaining nephrons, causing scarring. The scarring destroys more nephrons, which forces even more strain onto whatever’s left. This self-reinforcing cycle is what makes CKD progressive: once enough nephrons are damaged, kidney function declines steadily over months to years, even if the original cause is treated.
Leading Causes
Diabetes and high blood pressure are responsible for the majority of CKD cases. Type 2 diabetes alone accounts for an estimated 30% to 50% of all CKD and end-stage kidney disease, while type 1 diabetes contributes just under 4%. High blood pressure is the other major driver: roughly 1 in 5 adults with hypertension may have CKD. Both conditions damage the blood vessels inside the kidneys, accelerating that cycle of nephron loss and scarring.
Other causes include autoimmune conditions like lupus, inherited diseases such as polycystic kidney disease, recurrent kidney infections, prolonged obstruction of the urinary tract, and long-term use of certain pain medications. In some cases, no single cause is identified.
The Five Stages of CKD
CKD is classified by how well your kidneys filter blood, measured by a number called estimated glomerular filtration rate (eGFR). A higher number means better kidney function. The stages break down as follows:
- Stage 1 (eGFR 90 or above): Kidney function is normal or near-normal, but there’s evidence of damage such as protein in the urine.
- Stage 2 (eGFR 60 to 89): Mildly reduced function. Still typically no symptoms.
- Stage 3a (eGFR 45 to 59) and 3b (eGFR 30 to 44): Moderate loss of function. Waste products may begin building up in the blood.
- Stage 4 (eGFR 15 to 29): Severe loss. Symptoms become more noticeable, and planning for dialysis or transplant often begins.
- Stage 5 (eGFR below 15): Kidney failure. The kidneys can no longer sustain life without dialysis or a transplant.
Most people are diagnosed somewhere in stages 2 through 3, often incidentally through routine blood work. Because progression can take years, early detection makes a real difference in how long you can preserve the kidney function you still have.
Why Symptoms Appear Late
In stages 1 and 2, and often well into stage 3, your kidneys compensate well enough that you feel nothing unusual. This is the most deceptive aspect of CKD. Most people have no symptoms until the disease is advanced.
As kidney function drops into stages 4 and 5, waste and fluid build up in the body, causing a range of problems: nausea, vomiting, loss of appetite, persistent fatigue, trouble sleeping, reduced mental sharpness, shortness of breath (from fluid collecting in the lungs), and blood pressure that becomes increasingly difficult to control. Swelling in the ankles and feet, itchy skin, and changes in how often you urinate are also common at this point.
How CKD Is Diagnosed
Two simple tests form the basis of a CKD diagnosis. The first is a blood test for creatinine, a waste product from normal muscle activity. Your creatinine level is used to estimate your eGFR. Normal creatinine ranges are 0.74 to 1.35 mg/dL for adult men and 0.59 to 1.04 mg/dL for adult women, though values outside this range don’t automatically mean CKD.
The second is a urine test that measures the ratio of albumin (a protein) to creatinine. Healthy kidneys keep almost all protein in the blood, so protein leaking into urine signals damage. A ratio under 30 mg/g is normal. Between 30 and 300 mg/g indicates moderately increased protein loss, and 300 mg/g or above signals severely increased loss. Both your eGFR and your urine protein level factor into your diagnosis and staging. A doctor typically confirms CKD only if abnormal results persist for three months or longer.
Slowing the Progression
CKD cannot be reversed, but its progression can be significantly slowed, particularly when caught early. The strategy centers on controlling the conditions that damage kidneys in the first place.
Blood pressure management is critical. Medications that reduce pressure inside the kidney’s filtering units are typically the first line of treatment, as they protect nephrons beyond their blood-pressure-lowering effect. For people with diabetes, keeping blood sugar well controlled reduces ongoing damage to kidney blood vessels.
A newer class of medications originally developed for diabetes has shown strong benefits for kidney protection regardless of whether you have diabetes. These drugs work by reducing the pressure inside the kidney’s filters and decreasing how much glucose and sodium the kidneys reabsorb. Clinical trials have demonstrated that they meaningfully slow the decline in kidney function, and they’ve become a standard part of CKD management.
Dietary Changes
There is no single diet for everyone with CKD. In the early stages, you may have few restrictions at all. As the disease progresses, your kidneys become less effective at balancing key minerals in your blood, and dietary adjustments become more important.
Phosphorus is one concern. Damaged kidneys struggle to remove it, and high phosphorus levels pull calcium from bones and cause deposits in blood vessels. Foods with added phosphorus (found in many processed and packaged foods) raise blood levels more sharply than naturally phosphorus-containing foods like dairy or nuts. Potassium is another mineral that can accumulate when kidney function drops. Too much potassium in the blood can cause dangerous heart rhythm problems. The right intake level varies from person to person, so working with a dietitian who specializes in kidney disease is one of the most practical steps you can take.
Sodium reduction helps manage blood pressure and fluid retention. Protein intake also changes over the course of CKD. Eating less protein can reduce the workload on damaged kidneys, but once someone starts dialysis, protein needs actually increase.
Dialysis and Transplant
When kidneys fail completely or nearly so, two options replace their filtering function: dialysis and kidney transplant.
In-center hemodialysis is the most common form. You go to a dialysis center at least three times a week, where a machine filters your blood through an external circuit. Home hemodialysis allows 5 to 7 shorter sessions per week on your own schedule. Peritoneal dialysis uses the lining of your abdomen as a natural filter. It’s done every day but, when you factor in travel and waiting time at a center, often takes less total time out of your week than in-center hemodialysis.
A kidney transplant offers the closest thing to normal kidney function. A successful transplant eliminates the need for dialysis and generally provides a better quality of life, though it requires lifelong medication to prevent the body from rejecting the new kidney. Not everyone is a candidate, and wait times for a donor kidney can be years long, which is why many people start dialysis while waiting.
Who Should Be Screened
Because CKD is silent in its early stages, screening matters most for people at higher risk. If you have diabetes, high blood pressure, heart disease, or a family history of kidney failure, regular blood and urine testing can catch CKD years before symptoms appear. People over 60, those who are obese, and individuals with a history of acute kidney injury are also at elevated risk. A simple blood draw and urine sample are all it takes, and early detection is the single biggest factor in preserving kidney function long-term.