Kidney dialysis becomes necessary when the kidneys lose so much function that they can no longer filter waste from the blood on their own. This typically happens when kidney filtration drops to about 15% of normal capacity or lower. The causes range from chronic diseases that damage the kidneys over years to sudden injuries that shut them down in days. Diabetes alone accounts for roughly 50% of all cases worldwide, making it the single biggest driver of dialysis-requiring kidney failure.
How Diabetes Damages the Kidneys
Chronically high blood sugar harms the kidneys’ filtering units, called glomeruli, in several ways at once. Excess sugar in the bloodstream triggers a chain reaction: it stimulates proteins that ramp up scar tissue production, causes cells to enlarge, and accelerates collagen buildup inside the filters. Over time, the tiny blood vessels in the kidney thicken and stiffen, and the mesh-like tissue that supports the filters expands. The result is scarring that progressively chokes off the kidney’s ability to clean the blood.
This process also raises pressure inside the kidney’s filtering system, which creates a vicious cycle. Higher pressure forces more protein through the damaged filters and into the urine, a hallmark sign called proteinuria. Each round of damage and scarring reduces the number of working filters, pushing the remaining ones to work harder and fail faster. Many people with diabetes develop some degree of kidney involvement, but tight blood sugar and blood pressure control can slow the process significantly.
High Blood Pressure and Kidney Scarring
Chronic high blood pressure is the second leading cause of dialysis-requiring kidney failure. When blood pushes through the kidneys’ tiny arteries at elevated pressure year after year, it damages the vessel walls, the filtering units, and the surrounding tissue. The small blood vessels harden and narrow, reducing blood flow to the kidney tissue they supply. Starved of adequate circulation, those sections of kidney gradually scar over and stop functioning.
What makes hypertension particularly dangerous is that it often causes no symptoms until the damage is advanced. Many people don’t know their blood pressure is elevated, and the kidney damage accumulates silently over a decade or more. Because diabetes and high blood pressure frequently occur together, they can compound each other’s effects on the kidneys, accelerating the timeline to dialysis.
Immune System Attacks on the Kidneys
Several autoimmune and inflammatory conditions can cause the body’s immune system to attack kidney tissue directly. The umbrella term for inflammation of the kidney filters is glomerulonephritis, and it comes in many forms. Lupus is one of the most common culprits. It can target the kidneys along with the skin, joints, heart, and lungs. In some people, lupus-related kidney inflammation progresses to permanent scarring and kidney failure if not controlled.
IgA nephropathy occurs when a specific type of antibody builds up in the kidney filters, triggering chronic inflammation. It often progresses slowly, sometimes over 20 years or more, but can eventually destroy enough filtering capacity to require dialysis. A rarer condition called Goodpasture’s syndrome produces antibodies that directly attack the tissue lining the kidney filters, potentially causing rapid, permanent damage.
Blood vessel inflammation, known as vasculitis, can also starve kidney tissue of blood flow. Conditions like granulomatosis with polyangiitis affect small and medium blood vessels in the kidneys, lungs, and airways. Focal segmental glomerulosclerosis, where scarring develops in scattered sections of the filters, is another important cause, particularly in younger adults.
Polycystic Kidney Disease
Polycystic kidney disease (PKD) is the most common genetic cause of kidney failure. In the autosomal dominant form, which is passed from one parent, fluid-filled cysts grow throughout both kidneys over decades. These cysts gradually compress and replace healthy kidney tissue, while also promoting scarring in the tissue between the cysts. By middle age, many people with PKD have kidneys that are massively enlarged but largely nonfunctional, and roughly half will need dialysis or a transplant by their late 50s or 60s.
Urinary Blockages
Chronic obstruction of urine flow can quietly destroy the kidneys from the inside. When something blocks the path urine takes from the kidneys to the bladder, urine backs up and causes the kidneys to swell, a condition called hydronephrosis. Kidney stones and an enlarged prostate are among the most common culprits. If the blockage affects both kidneys and goes untreated, the sustained pressure damages kidney tissue permanently. At that point, dialysis or a transplant becomes necessary.
Sudden Kidney Failure
Not all dialysis is for chronic disease. Acute kidney injury can shut the kidneys down within hours or days, sometimes requiring temporary dialysis while they recover. Common triggers include sepsis (a severe bodywide infection), major blood loss from trauma or surgery, severe dehydration, and dangerously low blood pressure from shock or heart failure.
Certain medications and substances can also poison the kidneys. Common over-the-counter painkillers like ibuprofen and naproxen can cause acute kidney damage, especially when used at high doses or during dehydration. Some antibiotics, iodine-based contrast dyes used in CT scans, and recreational drugs carry similar risks. In many cases, the kidneys recover once the trigger is removed, and dialysis can be stopped. But severe or repeated acute injuries can leave lasting damage that eventually becomes chronic.
Environmental and Occupational Exposures
Heavy metals and environmental pollutants are an underappreciated cause of kidney disease. Mercury, lead, and cadmium have all been linked to chronic kidney damage. Lead exposure can come from old pipes, battery recycling, or manufacturing settings, and chronic exposure causes a specific pattern of gout and kidney disease. Cadmium enters the body mainly through contaminated food, particularly rice grown in cadmium-rich soil, and through cigarette smoke.
Farm workers face elevated rates of kidney disease linked to heavy herbicide and pesticide exposure. Air pollution is another contributor. A large study of U.S. veterans found that for every increase of 10 micrograms of particulate matter per cubic meter of air, new kidney disease cases rose 25 to 37%, and the risk of progressing to dialysis increased by 31%. Some herbal remedies and traditional medicines contain aristolochic acid, a plant compound that causes progressive kidney inflammation and has been responsible for regional epidemics of kidney failure, including one in the Balkans.
How Kidney Failure Feels Before Dialysis Starts
As kidney function declines toward the point of needing dialysis, waste products build up in the blood, a condition called uremia. The earliest symptoms are typically nausea and loss of appetite. You might feel queasy when you first wake up or lose interest in food after a few bites. A persistent metallic taste in the mouth, muscle cramps, and widespread itching are also common.
In advanced, untreated uremia, the signs become more dramatic. Breath can take on an ammonia-like smell, and yellowish-white crystals may form on the skin after sweating. Chest pain from inflammation around the heart and seizures can occur if treatment is delayed too long. Doctors typically recommend starting dialysis when early symptoms like mild nausea and appetite loss appear, rather than waiting for these severe complications. The decision is based on a combination of symptoms and blood tests measuring how well the kidneys are still filtering, with a filtration rate of 15 or below signaling kidney failure.