The most common kidney diseases are chronic kidney disease (CKD), kidney stones, kidney infections, glomerulonephritis, and polycystic kidney disease. CKD alone affects roughly 14% of adults worldwide, and diabetes and high blood pressure drive the majority of cases. Some of these conditions develop slowly over years with no obvious warning signs, while others strike suddenly with unmistakable pain or fever.
Chronic Kidney Disease
CKD is by far the most widespread kidney condition. Global estimates put the adult prevalence at 14.2%, a figure that has risen steadily since 1990. Most people fall into the earlier stages, where kidney function is only mildly to moderately reduced. The challenge is that CKD rarely causes symptoms until it has progressed significantly. In early stages, your kidneys compensate well enough that you feel normal.
Diabetes is the single largest driver, responsible for 44% of new cases of kidney failure. High blood pressure is the second leading cause. Both conditions damage the tiny blood vessels inside the kidneys over time, gradually reducing the organs’ ability to filter waste from your blood. Other contributors include obesity, smoking, heart disease, and a family history of kidney problems.
Doctors classify CKD into five stages based on how well your kidneys filter blood, measured by a number called GFR (glomerular filtration rate):
- Stage 1: GFR of 90 or above. Kidney damage is present but filtration is still normal.
- Stage 2: GFR 60 to 89. Mildly decreased function.
- Stage 3a/3b: GFR 30 to 59. Moderate loss of function, where symptoms may start to appear.
- Stage 4: GFR 15 to 29. Severe reduction, and planning for possible dialysis or transplant begins.
- Stage 5: GFR below 15. This is kidney failure.
When symptoms do eventually appear, they tend to include swelling in the legs, feet, or ankles, changes in urination frequency, foamy urine, fatigue, and difficulty concentrating. Because these signs overlap with many other conditions and show up late, routine blood and urine tests are the only reliable way to catch CKD early if you have risk factors like diabetes or hypertension.
Kidney Stones
Kidney stones form when minerals and salts in your urine crystallize inside the kidney. They range from grain-of-sand size to large enough to fill the entire interior of the kidney. The hallmark symptom is sudden, intense pain in the back or side that can radiate toward the lower abdomen and groin. Nausea, blood in the urine, and painful urination are also common.
About 80% of kidney stones are made of calcium oxalate, sometimes mixed with calcium phosphate. Uric acid stones account for roughly 9% of cases and are more common in people with gout or diets very high in animal protein. Struvite stones, sometimes called infection stones, make up about 7 to 10% and form in the setting of chronic urinary tract infections. Cystine stones are rare, representing about 1% of all stones, and are caused by an inherited condition.
Most small stones pass on their own within days to weeks with plenty of fluids and pain management. Larger stones, or those that block urine flow, may require procedures to break them apart using sound waves or to remove them surgically. The biggest modifiable risk factor is not drinking enough water. People who have had one stone have a significantly higher chance of developing another, so staying well hydrated and adjusting dietary habits (reducing sodium and oxalate-rich foods, for instance) can make a real difference in prevention.
Kidney Infections
A kidney infection, or pyelonephritis, is a urinary tract infection that has traveled upward from the bladder into one or both kidneys. It typically causes fever, pain in the back or side, groin pain, and painful or frequent urination. Unlike a simple bladder infection, a kidney infection can make you feel genuinely sick, with chills, nausea, and vomiting.
Women are more prone to kidney infections because of their shorter urinary tract, which gives bacteria a shorter path to travel. Other risk factors include kidney stones (which can trap bacteria), urinary catheter use, and any condition that impairs urine flow. Kidney infections require prompt antibiotic treatment. Left untreated, the infection can spread to the bloodstream or cause permanent scarring of kidney tissue.
Glomerulonephritis
Glomerulonephritis refers to inflammation of the glomeruli, the clusters of tiny filtering units inside each kidney. When these structures become inflamed, they leak blood and protein into the urine and lose their ability to remove waste efficiently. The condition can develop suddenly (acute) or gradually over months to years (chronic).
The most common form worldwide is IgA nephropathy, where an immune protein called IgA builds up in the glomeruli and triggers inflammation. It often shows up as blood in the urine during or shortly after a cold or respiratory infection. Other forms include lupus nephritis (linked to the autoimmune disease lupus), post-streptococcal glomerulonephritis (which can follow a strep throat infection, particularly in children), and several rarer autoimmune varieties.
Symptoms vary by type and severity but can include pink or cola-colored urine, foamy urine from excess protein, swelling in the face or legs, high blood pressure, and fatigue. Diagnosis usually involves blood tests, urine tests, and sometimes a kidney biopsy, where a small tissue sample is examined under a microscope to determine which type of glomerulonephritis is present and how much damage has occurred. Some forms resolve on their own, while others require medications that calm the immune system to prevent ongoing kidney damage.
Nephrotic Syndrome
Nephrotic syndrome is not a single disease but a pattern of kidney damage defined by three features: heavy protein loss in the urine (more than 3.5 grams per day), low blood protein levels, and swelling, particularly around the eyes, in the hands, and in the legs. When the kidney’s filters become too leaky, large amounts of a protein called albumin escape into the urine, pulling fluid out of the bloodstream and into surrounding tissues.
Several underlying conditions can cause nephrotic syndrome. In children, a condition called minimal change disease is the most common trigger, and it generally responds well to treatment. In adults, it is more often linked to diabetes-related kidney damage, a condition called focal segmental glomerulosclerosis, or membranous nephropathy. People with nephrotic syndrome also face a higher risk of blood clots and infections because they lose protective proteins through the urine.
Polycystic Kidney Disease
Polycystic kidney disease (PKD) is the most common inherited kidney disorder. The dominant form, ADPKD, affects roughly 1 in 400 to 1,000 people worldwide and causes fluid-filled cysts to grow throughout both kidneys over decades. These cysts gradually enlarge the kidneys and crowd out normal tissue, reducing function over time. About half of people with ADPKD develop kidney failure by their 50s or 60s.
The condition is caused by mutations in one of two genes. Mutations in the PKD1 gene account for about 85% of cases and tend to cause more severe disease with earlier kidney failure. Mutations in the PKD2 gene make up most of the remaining 15% and generally follow a slower course. Symptoms often begin between ages 30 and 50 and include back or side pain, high blood pressure, blood in the urine, and frequent kidney infections. Cysts can also develop in the liver and other organs.
Because PKD is genetic, there is no way to prevent it, but treatments can slow cyst growth and manage complications. Controlling blood pressure is critical, as hypertension develops early in most people with PKD and accelerates kidney damage. A newer class of medication that targets cyst growth has been shown to slow the decline in kidney function for some patients with rapidly progressing disease.
How These Conditions Overlap
Many of these diseases are interconnected. Chronic kidney disease is often the end result of poorly controlled diabetes, long-standing high blood pressure, recurrent kidney infections, or progressive glomerulonephritis. Kidney stones can lead to infections, and repeated infections can scar the kidneys enough to cause CKD. Polycystic kidney disease follows its own genetic timeline but ultimately leads to the same destination: reduced filtration and, in many cases, kidney failure.
The common thread across nearly all kidney diseases is that early detection makes a significant difference. A simple blood test measuring kidney filtration and a urine test checking for protein can catch problems years before symptoms appear. If you have diabetes, high blood pressure, a family history of kidney disease, or a history of kidney stones or recurrent infections, periodic screening gives you the best chance of catching damage while it can still be slowed or managed effectively.