Kidney disease is most often caused by diabetes and high blood pressure, which together account for the majority of cases worldwide. An estimated 788 million adults globally are living with chronic kidney disease, and many don’t know it until significant damage has already occurred. The causes range from common metabolic conditions to genetic disorders, medications, infections, and environmental exposures.
Diabetes: The Leading Cause
About 1 in 3 people with diabetes develop kidney disease, making it the single biggest driver of kidney failure. The damage happens gradually, often over years, and starts with a process that seems counterintuitive: your kidneys actually work too hard at first.
When blood sugar stays elevated, the kidneys ramp up their filtration rate in an attempt to clear the excess glucose. This overwork, called hyperfiltration, puts mechanical stress on the tiny filtering units inside each kidney. At the same time, high blood sugar triggers a cascade of inflammation and oxidative damage throughout the kidney’s blood vessels and tissues. The walls of the filtering units thicken, scar tissue forms, and specialized cells that act as the kidney’s final filter begin to die off. Sugar byproducts like fructose and sorbitol also build up inside kidney cells, increasing internal pressure until the cells swell and rupture.
The earliest sign of this damage is protein leaking into the urine, something you won’t notice on your own but that a simple lab test can detect. Left unchecked, the scarring spreads and the kidneys progressively lose their ability to filter waste from the blood.
High Blood Pressure and Blood Vessel Damage
About 1 in 5 people with high blood pressure develop kidney disease. The relationship also works in reverse: kidney damage raises blood pressure, creating a cycle that accelerates decline in both directions.
Your kidneys filter blood through an intricate network of tiny arteries. When blood pressure is chronically elevated, it overwhelms the protective mechanisms these vessels use to regulate internal pressure. The vessel walls thicken and stiffen in response, narrowing the channels that carry blood to the filtering units. This reduces blood flow to the kidney tissue itself, starving it of oxygen. Over time, entire sections of the kidney become scarred and nonfunctional. The remaining healthy tissue has to compensate by working harder, which only speeds up the damage.
Immune System Attacks on the Kidneys
Several autoimmune conditions directly target the kidney’s filtering units, causing inflammation known as glomerulonephritis. Two of the most common are lupus nephritis and IgA nephropathy.
Lupus is a chronic inflammatory disease that can affect the skin, joints, heart, lungs, and kidneys. When lupus targets the kidneys, the immune system deposits antibody complexes in the filtering units, triggering inflammation and scarring. IgA nephropathy happens when a specific type of antibody, normally part of your first line of defense against infections, accumulates in the kidneys instead. The resulting inflammation can simmer quietly for years, with blood in the urine often being the only clue. Both conditions can lead to progressive kidney failure if the inflammation isn’t controlled.
Genetic Kidney Disease
Polycystic kidney disease (PKD) is the most common inherited form of kidney disease, affecting 1 in 500 to 1,000 people. It causes fluid-filled cysts to grow throughout both kidneys, gradually replacing healthy tissue and enlarging the organs to many times their normal size.
The autosomal dominant form, which is far more common than the recessive form, requires only one copy of a mutated gene to develop. In about 90% of cases, the mutation is inherited from an affected parent. The remaining 10% arise spontaneously in people with no family history. If someone inherits the mutation in one gene copy but later develops a second mutation in the other copy, cysts tend to grow faster and the disease progresses more aggressively. Many people with PKD eventually need dialysis or a transplant, though the timeline varies widely.
Medications That Harm the Kidneys
Common over-the-counter painkillers, particularly nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and naproxen, are a well-documented cause of kidney injury. Taking seven or more standard daily doses per month is associated with a 20% increase in the risk of both sudden kidney injury and chronic kidney disease. In one large analysis, the median time from NSAID exposure to kidney injury was just six days, and nearly 80% of cases occurred within the first month.
The risk is highest for older adults and anyone whose kidney function is already slightly reduced, even if they don’t know it. NSAIDs work by blocking chemicals that, among other things, help maintain blood flow to the kidneys. Reduced blood flow leads to tissue damage, particularly in the tubules that handle the fine-tuning of what your kidneys keep and what they discard. Chronic use can also trigger inflammation within the kidney tissue itself, a condition called interstitial nephritis.
Prescription medications can also be culprits. Certain antibiotics, antifungal drugs, and proton pump inhibitors (commonly used for acid reflux) have all been linked to kidney inflammation. The risk generally rises with higher doses and longer use.
Physical Blockages
When something blocks the flow of urine out of the body, pressure builds backward toward the kidneys. Kidney stones and an enlarged prostate are the most common culprits. The trapped urine causes the kidneys to swell, a condition called hydronephrosis. If the blockage affects both kidneys and isn’t treated promptly, the sustained pressure can cause permanent damage and eventually kidney failure.
Even partial blockages that persist for weeks or months can silently erode kidney function. The key factor is how long the obstruction lasts. Short-term blockages, once relieved, usually allow full recovery. Prolonged blockages may leave lasting scarring.
Sudden Kidney Injury
Unlike chronic kidney disease, which develops over months or years, acute kidney injury happens within hours or days. The most common triggers fall into two categories: conditions that reduce blood flow to the kidneys and conditions that damage kidney tissue directly.
Severe dehydration, major blood loss, sepsis (a life-threatening response to infection), and anaphylaxis can all slash blood flow to the kidneys so dramatically that tissue begins to die. This is the most frequent cause of sudden kidney injury in hospitalized patients. When kidney tissue is starved of blood for too long, the tubular cells that do much of the kidney’s work begin to break down, a process called acute tubular necrosis.
Certain medications, contrast dyes used in imaging scans, and the breakdown products released during severe muscle injury (rhabdomyolysis) can poison kidney cells directly. Avoiding dehydration and unnecessary use of drugs known to stress the kidneys are the most practical ways to lower your risk.
Environmental and Occupational Exposures
Heavy metals are a lesser-known but significant cause of kidney damage. Lead, cadmium, mercury, arsenic, and copper can all injure the tubular cells that line the kidney’s internal plumbing. Lead accumulates in these cells over time, causing chronic inflammation and scarring. Cadmium exposure, which can come from contaminated water, food, or tobacco smoke, is particularly harmful to the kidneys and is a recognized occupational hazard in industries like battery manufacturing and metal smelting.
The damage from heavy metals typically shows up as abnormal amounts of protein and amino acids in the urine, reflecting the tubules’ inability to reabsorb substances that should stay in the blood. With some metals, like mercury and gold, the filtering units themselves bear the brunt of the damage instead. People with ongoing occupational exposure face the highest risk, but environmental contamination and smoking also contribute meaningfully to the burden of kidney disease worldwide.
Other Risk Factors That Compound the Damage
Heart disease is a major independent risk factor for kidney disease. The kidneys depend on steady, well-oxygenated blood flow to function, and a weakened heart delivers less of it. Family history of kidney failure also raises your risk, even in the absence of a known genetic condition like PKD, suggesting that subtler inherited traits influence how resilient your kidneys are to other insults.
Obesity, smoking, and older age all accelerate kidney decline by worsening inflammation, blood vessel damage, and blood pressure. These factors rarely cause kidney disease on their own, but they amplify the harm done by diabetes, hypertension, and other primary causes. In many people, kidney disease results not from a single cause but from several overlapping risks compounding over decades.