The four types of kidney disease most commonly discussed are chronic kidney disease (CKD), acute kidney injury (AKI), polycystic kidney disease (PKD), and glomerular disease. Each affects the kidneys differently, progresses on its own timeline, and calls for a distinct approach to management. Globally, about 14.6% of adults are living with some form of kidney disease, with CKD accounting for the vast majority of cases.
Chronic Kidney Disease (CKD)
Chronic kidney disease is the slow, progressive loss of kidney function over months or years. It is by far the most common type, and the two biggest drivers are diabetes and high blood pressure. Together, these conditions damage the tiny blood vessels inside the kidneys that filter waste from your blood. Glomerular diseases and recurring kidney infections can also lead to CKD over time.
CKD is classified into five stages based on how well your kidneys are filtering. Doctors measure this with a blood test called eGFR (estimated glomerular filtration rate), which gives a score roughly reflecting the percentage of normal kidney function you still have:
- Stage 1 (eGFR 90+): Kidney damage is present, often detected by protein in the urine, but filtration is still normal.
- Stage 2 (eGFR 60–89): Mild loss of function, usually without noticeable symptoms.
- Stage 3a (eGFR 45–59) and 3b (eGFR 30–44): Moderate loss of function. Fatigue, swelling, and changes in urination may start to appear.
- Stage 4 (eGFR 15–29): Severe loss of function. Symptoms become more pronounced, and preparation 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.
Early stages are often completely silent. A urine test measuring albumin (a protein that leaks into urine when kidneys are damaged) can catch problems before symptoms develop. A normal result is less than 30 mg/g. Anything above that may signal kidney disease, even if your eGFR still looks fine.
Managing CKD focuses on slowing the decline. Controlling blood sugar and blood pressure is foundational. A newer class of medications originally designed for diabetes has shown striking results: large clinical trials found these drugs reduce the risk of kidney disease progression by about 37%, regardless of whether the person has diabetes. Dietary changes also matter. For people with stage 3 through 5 CKD, guidelines recommend reducing protein intake to roughly 0.55 to 0.60 grams per kilogram of body weight per day. For a 150-pound person, that translates to about 37 to 41 grams of protein daily, significantly less than what most people eat.
Acute Kidney Injury (AKI)
Unlike CKD’s gradual decline, acute kidney injury is a sudden drop in kidney function that develops over hours or days. It’s most common in people who are already hospitalized, particularly those in intensive care, though it can happen to anyone. Common triggers include severe dehydration, a sharp drop in blood pressure (from major bleeding or sepsis), a reaction to certain medications, or a physical blockage preventing urine from leaving the kidneys.
Doctors diagnose AKI when blood levels of creatinine (a waste product your kidneys normally clear) spike by a specific amount within 48 hours, or when urine output drops below roughly half a milliliter per kilogram of body weight per hour for six hours or more. In plain terms, if you’re producing far less urine than usual and feeling suddenly unwell, that’s a red flag.
Symptoms can include swelling in the legs and ankles, nausea, confusion, and significantly reduced urination. The good news is that AKI is often reversible if the underlying cause is treated quickly. However, severe or repeated episodes of AKI can leave lasting damage and increase the risk of developing CKD later on. Recovery depends heavily on what caused the injury and how fast treatment begins.
Polycystic Kidney Disease (PKD)
Polycystic kidney disease is a genetic condition in which clusters of fluid-filled cysts grow inside the kidneys, gradually enlarging them and crowding out healthy tissue. It comes in two forms, distinguished by how it’s inherited.
The dominant form is far more common, affecting 1 in 500 to 1,000 people. You only need to inherit one copy of the altered gene from one parent to develop it. Symptoms typically appear between the ages of 30 and 50 and include flank pain, high blood pressure, blood in the urine, and kidney stones. Over time, the cysts can grow large enough that you can feel them, and the kidneys may swell to several times their normal size.
The recessive form is much rarer, occurring in roughly 1 in 20,000 to 40,000 people. It requires an altered gene from both parents and tends to cause problems much earlier, often in infancy or childhood. It can affect the liver as well as the kidneys and is generally more severe.
There is no cure for PKD, but treatment can slow cyst growth and manage complications like high blood pressure and pain. Many people with the dominant form maintain adequate kidney function into middle age, though a significant number eventually progress to kidney failure and need dialysis or a transplant.
Glomerular Disease
Glomerular diseases target the glomeruli, the microscopic filtering units inside each kidney. Healthy kidneys contain about a million of them, and their job is to separate waste from the things your body needs to keep, like protein and red blood cells. When the glomeruli become inflamed or damaged, those substances start leaking into the urine.
Glomerular diseases show up in two main patterns. The first, called nephrotic syndrome, is defined by heavy protein loss in the urine (more than 3 grams per day), low protein levels in the blood, and noticeable swelling, particularly around the eyes, ankles, and feet. The second pattern, nephritic syndrome, involves blood in the urine alongside protein loss, rising blood pressure, and declining kidney function. Nephritic syndrome generally carries a worse prognosis.
The causes are varied. Some glomerular diseases are triggered by the immune system attacking the kidneys directly. Others develop as a complication of infections, diabetes, or lupus. In some cases, no clear cause is found. Treatment depends on the specific type and ranges from medications that suppress immune activity to careful blood pressure control. Left untreated, glomerular disease is one of the leading pathways to CKD and eventual kidney failure.
How These Types Overlap
These four categories aren’t always separate stories. Glomerular disease and PKD frequently lead to CKD if they progress far enough. Repeated episodes of AKI raise CKD risk. And someone with CKD is more vulnerable to AKI because their kidneys have less reserve to handle a sudden insult like dehydration or a new medication.
Two screening tests catch the vast majority of kidney problems early: a blood test for eGFR and a urine test for albumin. Both are simple, inexpensive, and routinely available. If you have diabetes, high blood pressure, or a family history of kidney disease, regular screening gives you the best chance of catching damage in a stage where treatment can make the biggest difference.