Renal Failure Tests

If you have acute renal failure or are living with chronic kidney disease, your provider may need to do renal failure tests to check on your health. Kidney failure, or end-stage renal disease, means your kidneys are not functioning well enough for you to survive without treatment like a transplant or dialysis.

Renal failure tests can include blood and urine tests to measure how well your kidneys are filtering out waste and to check for proteins like albumin. You may also need imaging tests or a kidney biopsy to rule out other illnesses or find an underlying cause for kidney failure.

This article will cover renal failure tests, including what to expect if you need to have them done.

What Are the Signs and Symptoms of Kidney Disease?

Acute and chronic kidney disease can cause signs and symptoms that signal there is a problem with your kidney function. Signs of acute kidney failure include:

• Suddenly not urinating as much or at all 
• Nausea
• Fatigue
• Weakness
• Shortness of breath
• Swelling of the legs, feet, or ankles 
• Irregular heartbeat
• Chest pain or pressure
• Confusion
• Seizures

Sometimes, a person with acute kidney failure (also called acute kidney injury) does not have any symptoms and they only find out their kidneys are not working when they have medical tests done.

Signs of chronic kidney disease include:

• Fatigue and weakness
• Breath that smells odd (like ammonia) 
• Not feeling hungry 
• Dry, itchy skin
• Swollen feet and ankles
• Puffy eyes in the morning 
• Urinating more (especially at night) 
• Trouble sleeping
• Muscle cramps (especially at night) 
• Trouble concentrating

Labs and Tests

Your provider will probably want to do some labs and tests to check your kidney function and test you for renal failure.

Blood Tests

You may give a sample of your blood to be checked in a lab. One blood test is the glomerular filtration rate (GFR), which measures whether the kidneys are filtering at a normal rate.

Your provider might also want to test your blood to see how much creatinine there is in it. Creatinine is a waste substance your kidneys usually help clear from your body. If your kidneys are not working well, you may have more creatinine in your blood than normal.

Urine Tests

You may need to give a urine sample to have it checked in a lab for the following: 

• Creatinine: This test measures how much of a waste product called creatinine is in the urine. The kidneys are responsible for getting rid of creatinine, so if there is not much in the urine, it means the kidneys are not doing their job well.
  
• Albumin: Healthy kidneys do not let albumin into the urine, therefore, the amount of albumin in the urine can be an indicator of kidney function. Your provider can either use a dipstick test (where a strip changes color to show if there is albumin in it) or the urine albumin-to-creatinine ratio test (UACR). This test measures both substances and estimates how much the kidneys are able to process out of the body.

Biopsy

Sometimes, a kidney biopsy is necessary if the provider needs more information either about a suspected disease process or how quickly the kidney damage or failure is progressing.

A biopsy can be done with a needle inserted into the kidney, guided by ultrasound. The needle then removes kidney tissue for microscopic examination in a lab.

Self-Checks/At-Home Testing

Right now, there are no self-checks for renal failure. It’s important that you know the signs and symptoms of kidney disease and see your provider if you think there could be something wrong with your kidneys.

There are at-home tests to check for kidney function, but these tests should not be used to check for kidney failure. These tests are often recommended in the early stages of kidney disease for people who have trouble leaving home or do not have medical insurance.

Physical Examination

The symptoms of kidney disease and kidney failure can be vague or seem like they could be related to a different health condition, especially in the early stages. 

To start, your provider will want to do a physical exam to get a sense of your overall health. A chest and abdominal exam can help your provider see if there is swelling of your abdomen or fluid in your lungs. Gently striking of the back that causes pain can indicate a urinary tract obstruction. 

Your provider will also check your chest and abdomen by touching, and gently pressing to feel for anything abnormal. Through doing this, they may find masses or signs that the kidneys are bigger than normal (kidney enlargement).

An exam of your skin can show:

• Paleness caused by anemia (low red blood cell count)
• Skin discoloration from urochrome deposits (the pigment that makes urine yellow is deposited into the skin because of problems eliminating it)
• Hyperpigmentation (patches of skin that are darker than the surrounding skin)
• Petechiae (little rash-like spots of blood) from platelet abnormalities
• Scratch marks from itching due to abnormal phosphorus levels
• Dry skin caused by sweat gland problems
  

While they’re doing a physical exam, a provider can also talk to you and see how you’re feeling. This can be helpful because people with acute renal failure may have slurred speech, be confused or drowsy, or have trouble paying attention. 

Imaging Tests

Imaging tests can help your provider get a closer look at your kidneys. There are a few imaging tests they might want to do:

• Ultrasound: Ultrasounds use sound waves to create a picture of your kidneys. It can check for size abnormalities or obstructions.
• CT (computed tomography) scan: A CT uses X-rays to look for structural problems or abnormalities in the kidneys. 

Differential Diagnosis

There are other conditions that can cause the signs and symptoms of kidney failure. Your provider will want to make sure that you do not have any of these conditions before diagnosing you with renal failure:

• Sepsis
• Poor fluid intake
• Congestive heart failure
• Cirrhosis
• Toxins
• HELLP syndrome
• Ischemia (reduced blood flow)
• Systemic lupus erythematosus
• Lymphoma
• Leukemia
• Prostate cancer
• Cervical cancer
  

Your provider will rule these causes out to ensure a correct diagnosis is made.

How Is Kidney Disease Treated?

If your provider tells you that you have kidney disease, the treatment will depend on what’s causing your kidneys to fail and how serious the condition is.

For example, if you have acute kidney failure, you may need to be in the hospital to get fluids in an IV, medications to help get rid of the extra fluids, and other treatments that help your body do important jobs like clearing toxins from your body while your kidneys need a rest (hemodialysis). 

You may get better after acute kidney failure if it is treated and the underlying cause is taken care of—for example, an injury to the organ heals or you stop taking a medication that damaged your kidneys.

If you have chronic kidney disease, you’ll need to learn how to live with the condition and prevent complications. Your provider will talk to you about taking steps like changing your diet and starting medications that will help prevent your kidneys from being under too much stress and that can help manage your overall health.

For example, you may need to take medications to lower your blood pressure and may need to change your diet so you’re eating less protein (which can be hard on your kidneys). If your condition is severe, you may need to have treatment like dialysis that does your kidney’s work for them. At some point, you may need to have a kidney transplant. 

When to See a Healthcare Provider

You should call your provider if you’re having symptoms that are concerning to you. For example, you notice that you’re peeing a lot more often or a lot less than usual, or you have swelling in your feet or hands. 

Sometimes, people only learn they have kidney disease when they’re having medical tests for something else. If your provider thinks your symptoms could be related to your kidneys, they’ll do tests to check them. 

Summary

Renal failure tests can be used to check you for acute or chronic kidney disease. If you have signs or symptoms of kidney failure, your provider may check your blood and urine as well as do imaging tests to see how your kidneys are working. 

The treatment you need will be based on what the renal failure tests say and what diagnosis your provider gives you.