Kidney failure happens when the kidneys can no longer filter enough waste and fluid to keep the body working. The most common symptoms are producing much less urine, swelling in the legs, feet or face, shortness of breath, deep exhaustion, confusion, nausea, severe itching, a metallic taste in the mouth, muscle cramps and chest pain. Chest pain, trouble breathing, confusion or a sudden drop in urine can be life threatening and need emergency care right away.
The tricky part is that many early signs feel like a long week. Tired, puffy, achy and a little off is easy to blame on stress or getting older. That’s how kidney disease stays hidden. The CDC estimates that as many as 9 in 10 adults with chronic kidney disease do not know they have it.
What causes kidney failure?
Kidney failure can build slowly over years as chronic kidney disease reaches stage 5, when kidney function falls below about 15% of normal. It can also hit fast, within hours or days, after a severe illness, an injury, serious dehydration or a reaction to certain medicines. That sudden form, called acute kidney failure, can sometimes be reversed with quick treatment.
What are the warning signs of kidney failure?
- Less urine. A sharp drop in urine is one of the clearest signs, especially when it happens suddenly. Urine may look dark, brown or bloody. In chronic kidney failure, some people still make normal amounts while their kidneys fail to clean the blood, so normal output does not guarantee healthy kidneys.
- Spreading swelling. Fluid and salt build up, often starting in the ankles and feet before moving to the hands and face. Puffy eyes or shoes that suddenly feel tight can be early clues.
- Shortness of breath. Fluid can collect in the lungs, which makes breathing harder, especially when lying flat. Some people describe feeling like they cannot catch their breath after small tasks.
- Constant exhaustion. Failing kidneys make less of the hormone that tells the body to produce red blood cells. The resulting anemia can bring weakness and a feeling of being cold even in a warm room.
- Confusion or brain fog. Waste in the blood can affect the brain, causing memory slips and trouble focusing. In severe cases it can lead to seizures.
- Nausea and appetite loss. A buildup of waste called uremia often causes vomiting, unplanned weight loss and a sudden dislike of foods like meat.
- A metallic taste. Uremia can make food taste like metal and leave breath smelling like ammonia.
- Severe itching. Mineral imbalances can cause itching that lotion does not help.
- Cramps and twitching. When calcium, phosphorus and potassium fall out of balance, muscles can cramp, twitch or weaken.
- Chest pain or an irregular heartbeat. Fluid around the heart or dangerously high potassium can disrupt its rhythm. This is one of the most dangerous signs.
Why are Black Americans at higher risk for kidney failure?
Black Americans are about three times as likely as white Americans to develop kidney failure. Higher rates of diabetes and high blood pressure, gaps in access to care and gene variants more common in people of African ancestry all play a role.
The tools also played a role. For years, doctors estimated kidney function with a formula that adjusted results for Black patients. Research found that the race based version could make Black patients’ kidneys appear to work better than they did, which delayed diagnoses and transplant listings. Major kidney groups dropped it in 2021, and the national transplant system required race neutral calculations starting July 27, 2022.
Patients who were harmed got some of that time back. Beginning in January 2023, every kidney transplant program had to identify Black candidates whose wait time was based on the old formula and check whether they should have qualified sooner. Nationally, 32% of Black candidate listings, more than 14,400, received extra waiting time. In the first six months alone, the median credit was 1.7 years. If you or a loved one were on a kidney waitlist before mid 2022, ask your transplant center whether your waiting time was reviewed.
Who else is at risk for kidney failure?
Diabetes and high blood pressure are the leading causes. Heart disease, obesity, a family history of kidney failure and long term use of certain pain relievers also raise the risk.
How is kidney failure treated?
The main options are dialysis, which filters blood through a machine or the lining of the belly, and a kidney transplant, which offers many patients the closest thing to normal life. Some people choose supportive care focused on comfort. Doctors also treat related problems like anemia and mineral imbalances.
If you have risk factors, ask your doctor for two simple tests, an eGFR blood test and a urine test for protein. Finding kidney disease early leaves the most options open.
This article is for general information and is not medical advice. If you have chest pain, severe shortness of breath, confusion, fainting, a seizure, an irregular heartbeat or a sudden drop in urine, call 911 or go to an emergency room.
