How Kidney Failure Is Diagnosed

Kidney failure, or end-stage renal disease, means the kidneys aren't functioning enough for you to survive without treatment like a transplant or dialysis.

If you’ve been living with chronic kidney disease, your healthcare provider has likely been monitoring your kidney function and your health. Acute renal failure is sudden kidney failure that happens within several hours to days.

To diagnose kidney failure, a variety of tests will need to be done, like blood and urine tests to measure how well your kidneys are filtering out waste and to check for protein like albumin. You may also undergo imaging tests or a kidney biopsy to rule out other illnesses or explore underlying causes of kidney failure.

This article will review how kidney failure is diagnosed. Knowing what you might be able to expect can help make things a little less nerve-racking.

Self-Checks/At-Home Testing

Right now, there are no self-checks for kidney failure. Being aware of the symptoms of kidney disease and kidney failure is important and can be a sign that you need to see your healthcare provider immediately for evaluation. Your provider can then do an exam and order the necessary tests to diagnose kidney failure.

There are at-home tests to check for kidney function, but these shouldn't be used to assess kidney failure. These are often recommended in the early stages of kidney disease for those who have trouble leaving their homes or don't have medical insurance.

Physical Examination

Because the symptoms of kidney disease and kidney failure can sometimes be nonspecific, especially in the early stages, a physical exam can be helpful.

A chest and abdominal exam can show swelling of the abdomen or fluid in the lungs. Gentle striking of the back that causes pain can indicate a urinary tract obstruction. Your healthcare provider will likely explore your chest and abdomen by touch, gently pressing to feel for anything abnormal. Through doing this, they may discover masses or kidney enlargement.

Examination of the 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 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
  

Those with acute renal failure may have slurred speech, be confused or drowsy, or show inattentiveness.

All of these aspects of the physical examination can provide important information about the extent of kidney failure and aid in diagnosis.

Labs and Tests

In addition to a physical examination, your provider will likely order labs and tests to help evaluate kidney function and assess for kidney failure. Tests can include:

• Blood test for glomerular filtration rate (GFR): This measures whether the kidneys are filtering at a normal rate.
• Urine test for albumin: Healthy kidneys don’t let albumin into the urine, therefore, the amount of albumin in the urine can be an indicator of kidney function.
  

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.

This 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.

New research is being done for tests that are less invasive. One such study involves the use of a cotton thread-based colorimetric sensor that measures glucose and urea from sweat. The sensor can distinguish between normal and abnormal readings and may be a useful tool in helping individuals measure and monitor their glucose (blood sugar) and/or urea levels in a noninvasive way. More research needs to be done, but this is promising.

Imaging Tests

Imaging tests can help your healthcare provider get a better sense of what might be going on with your kidneys.

An ultrasound uses sound waves to create a picture of your kidneys. It can check for any size abnormalities or obstructions.

A CT (computed tomography) scan uses an X-ray for similar reasons, as well as to look for structural problems or abnormalities.

Differential Diagnosis

Especially with acute renal failure, healthcare providers will rule out other possible causes of your symptoms. The three categories of acute renal failure are:

• Prerenal acute failure: Marked by reduced kidney blood flow
• Intrinsic acute renal failure: Caused by damage to the renal parenchyma (the functional part of the kidney)
• Postrenal acute renal failure: Caused by urinary tract obstruction

Knowing more about what kind of acute renal failure you have can help providers determine the cause of the kidney failure. If there's a specific underlying cause, like a toxin or blockage, it can be addressed while also providing medical treatment and support.

Other possible causes for symptoms of kidney failure include:

• 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.

Summary

Diagnosing kidney failure accurately is important to get appropriate treatment. To get a proper diagnosis, various blood and urine tests may be done, as well as physical examination. Depending on what labs show and what a physical exam turns up, your healthcare provider may also order imaging tests, which can show what's going on with your kidneys in more detail.

This may lead to a kidney biopsy for more clinical information. All of these tests can help your provider rule out other potential causes for your symptoms, and come to a definitive diagnosis, which will help to guide treatment.

A Word From Verywell

This might all seem overwhelming, especially if you're worried about keeping your kidney disease under control. Talk with your healthcare provider about signs you should be aware of and the diagnostic tests they'll do to monitor your condition. The tests themselves may provoke anxiety, but an accurate diagnosis is necessary to proceed with appropriate treatment.