Your kidneys are a pair of organs located toward your lower back. One kidney is on each side of your spine. They filter your blood and remove toxins from your body. Kidneys send toxins to your bladder, which your body later removes toxins during urination.
Kidney failure occurs when your kidneys lose the ability to sufficiently filter waste from your blood. Many factors can interfere with your kidney health and function, such as:
- toxic exposure to environmental pollutants or certain medications
- certain acute and chronic diseases
- severe dehydration
- kidney trauma
Your body becomes overloaded with toxins if your kidneys can’t do their regular job. This can lead to kidney failure, which can be life-threatening if left untreated
Usually someone with kidney failure will have a few symptoms of the disease. Sometimes no symptoms are present. Possible symptoms include:
- a reduced amount of urine
- swelling of your legs, ankles, and feet from retention of fluids caused by the failure of the kidneys to eliminate water waste
- unexplained shortness of breath
- excessive drowsiness or fatigue
- persistent nausea
- confusion
- pain or pressure in your chest
- seizures
- coma
Early signs of kidney failure
Symptoms of early stage kidney disease may be difficult to pinpoint. They’re often subtle and hard to identify. If you experience early signs of kidney disease, they may include:
- decreased urine output
- fluid retention that leads to swelling in limbs
- shortness of breath
Kidney failure can be the result of several conditions or causes. The cause typically also determines the type of kidney failure.
People who are most at risk usually have one or more of the following causes:
Loss of blood flow to the kidneys
A sudden loss of blood flow to your kidneys can prompt kidney failure. Some conditions that cause loss of blood flow to the kidneys include:
- a heart attack
- heart disease
- scarring of the liver or liver failure
- dehydration
- a severe burn
- an allergic reaction
- a severe infection, such as sepsis
High blood pressure and anti-inflammatory medications can also limit blood flow.
Urine elimination problems
When your body can’t eliminate urine, toxins build up and overload the kidneys. Some cancers can block the urine passageways, such as:
- prostate (most common type in men)
- colon
- cervical
- bladder
Other conditions can interfere with urination and possibly lead to kidney failure, including:
- kidney stones
- an enlarged prostate
- blood clots within your urinary tract
- damage to your nerves that control your bladder
Other causes
Some other things that may lead to kidney failure include:
- a blood clot in or around your kidneys
- infection
- an overload of toxins from heavy metals
- drugs and alcohol
- vasculitis, an inflammation of blood vessels
- lupus, an autoimmune disease that can cause inflammation of many body organs
- glomerulonephritis, an inflammation of the small blood vessels of the kidneys
- hemolytic uremic syndrome, which involves the breakdown of red blood cells following a bacterial infection, usually of the intestines
- multiple myeloma, a cancer of the plasma cells in your bone marrow
- scleroderma, an autoimmune condition that affects your skin
- thrombotic thrombocytopenic purpura, a disorder that causes blood clots in small vessels
- chemotherapy drugs that treat cancer and some autoimmune diseases
- dyes used in some imaging tests
- certain antibiotics
- uncontrolled diabetes
There are five different types of kidney failure:
Acute prerenal kidney failure
Insufficient blood flow to the kidneys can cause acute prerenal kidney failure. The kidneys can’t filter toxins from the blood without enough blood flow. This type of kidney failure can usually be cured once your doctor determines the cause of the decreased blood flow.
Acute intrinsic kidney failure
Acute intrinsic kidney failure can result from direct trauma to the kidneys, such as physical impact or an accident. Causes also include toxin overload and ischemia, which is a lack of oxygen to the kidneys.
The following may cause ischemia:
- severe bleeding
- shock
- renal blood vessel obstruction
- glomerulonephritis
Chronic prerenal kidney failure
When there isn’t enough blood flowing to the kidneys for an extended period of time, the kidneys begin to shrink and lose the ability to function.
Chronic intrinsic kidney failure
This happens when there’s long-term damage to the kidneys due to intrinsic kidney disease. Intrinsic kidney disease develops from a direct trauma to the kidneys, such as severe bleeding or a lack of oxygen.
Chronic post-renal kidney failure
A long-term blockage of the urinary tract prevents urination. This causes pressure and eventual kidney damage.
There are several tests your doctor can use to diagnose kidney failure.
Urinalysis
Your doctor may take a urine sample to test for any abnormalities, including abnormal protein or sugar that spills into the urine.
They may also perform a urinary sediment examination. This test measures the amount of red and white blood cells, looks for high levels of bacteria, and searches for high numbers of tube-shaped particles called cellular casts.
Urine volume measurements
Measuring urine output is one of the simplest tests to help diagnose kidney failure. For example, low urinary output may suggest that kidney disease is due to a urinary blockage, which multiple illnesses or injuries can cause.
Blood samples
Your doctor may order blood tests to measure substances that are filtered by your kidneys, such as blood urea nitrogen (BUN) and creatinine (Cr). A rapid rise in these levels may indicate acute kidney failure.
Imaging
Tests like ultrasounds, MRIs, and CT scans provide images of the kidneys themselves as well as the urinary tract. This allows your doctor to look for blockages or abnormalities in your kidneys.
Kidney tissue sample
Tissue samples are examined for abnormal deposits, scarring, or infectious organisms. Your doctor will use a kidney biopsy to collect the tissue sample. A biopsy is a simple procedure that’s usually performed while you’re awake.
Your doctor will give you a local anesthetic so you don’t feel any pain. They’ll then insert a biopsy needle through your skin and down into your kidney to get the sample. X-ray or ultrasound equipment will locate the kidneys and help your doctor in guiding the needle.
These tests can help determine whether your kidneys are functioning as they should. Other kidney function tests may also help your doctor determine what’s causing the symptoms.