Urine Albumin and Albumin to Creatinine Ratio

Purpose of the test

The purpose of a urine albumin test is to determine if there is an abnormal amount of the protein albumin in a urine sample.

Excess albumin on this type of test indicates that too much of this protein has passed from the blood to the urine, which can reflect a problem with the kidneys. Different types of urine albumin tests can be used for diagnosis, screening, and monitoring of kidney disease.

Diagnosis

Diagnosis includes medical exams or tests that are done after symptoms have appeared. A urine albumin test may be included in the diagnostic process if you notice health changes that could be caused by kidney problems.

Examples of symptoms that can be related to kidney impairment include urinary irregularities such as frothy urine, blood in the urine, or changes in urine volume or frequency. Abnormal swelling, itching, loss of appetite, and fatigue can also occur as a result of kidney problems.

Screening

Screening tests are designed to try to find health problems before symptoms occur with the goal of enabling treatment before a disease has significantly progressed. Because the early stages of kidney disease may not cause symptoms, urine albumin tests are often used to look for indications of kidney problems.

A urine albumin-to-creatinine ratio test is a common way to screen for high levels of albumin, which is known as albuminuria. This screening is most often done in people who have a higher risk of kidney disease including people with diabetes, high blood pressure, or a family history of kidney problems. Screening may also be recommended in older adults and people in some racial and ethinc groups.

Screening for kidney disease may combine a urine albumin test with another kidney function test, known as an estimated glomerular filtration rate (eGFR) test, that assesses how well the kidneys are filtering the blood.

The presence of moderate or severely increased levels of albumin in the blood has also been associated with cardiovascular disease, obesity, and diabetes, so screening with urine albumin tests may provide information about risks related to these conditions and their potential complications.

Monitoring

Another use of urine albumin tests is for monitoring kidney health over time. This often means using repeat urine albumin tests at regular intervals to check how kidney disease is progressing or to see how well treatments are working.

What does the test measure?

A urine albumin test is a measurement of the protein albumin. Albumin is a common protein in the blood that helps keep fluid from leaking out of blood vessels. Albumin also helps carry substances, including enzymes and vitamins, through the body.

While albumin is supposed to be found in the blood, very little albumin should enter the urine if the kidneys are functioning properly. Different types of urine albumin tests are designed to detect albumin in the urine:

• A urine dipstick test is a test in which a test strip turns a different color based on the amount of albumin in the sample.
• A 24-hour urine sample requires collecting all of your urine for a full day. The laboratory then measures the total amount of albumin in that complete sample.
• An albumin-to-creatinine ratio test measures both albumin and creatinine in a one-time sample, also known as a spot urine sample. Creatinine is a chemical byproduct of normal muscle activity, and it is normally removed from the body in urine. Total daily creatinine production is relatively consistent, so an albumin-to-creatinine ratio test is a way to estimate your total daily urine albumin level without having to do a full 24-hour urine sample.

A dipstick test does not provide an exact measurement of albumin.

A 24-hour urine sample provides an albumin measurement that is typically listed as milligrams per 24 hours (mg/24 hours).

An albumin-to-creatinine ratio test is reported in milligrams of albumin per gram of creatine (mg/g) found in one deciliter of urine. This may also be listed in international units, which are measured in milligrams per millimole (mg/mmol).

Some laboratories or health professionals may report urine albumin test results using an estimated albumin excretion rate (eAER). The eAER is a calculation with a formula that incorporates the albumin-to-creatinine ratio with the ability to adjust the expected daily creatinine level based on individual factors such as body composition, age, sex, and race. While not broadly used, the eAER may be most beneficial for patients with abnormal daily production of creatinine.

When should I get a urine albumin or albumin-to-creatinine ratio test?

Urine albumin tests can be used in several different medical contexts.

For diagnosis, they are generally performed if you have signs of possible kidney impairment. Urinary changes, swelling, and unexplained itching are examples of symptoms that can be associated with kidney problems. In these cases, a urine albumin test may be performed along with other kidney function tests.

Screening with a urine albumin test is only recommended for some people. For people without risk factors for kidney disease, the downsides of this testing, including financial costs and potential unnecessary follow-up, are considered to be greater than the potential benefits. As such, this screening is not recommended in the population in general.

Instead, screening is usually reserved for people who are at a higher risk of having kidney problems. Urine albumin testing is recommended for people with diabetes, and this testing may be done every year for people with type 2 diabetes.

Screening is also advised in people with one or more of the following risk factors for kidney disease:

• High blood pressure
• A family history of chronic kidney disease
• Obesity
• Cigarette smoking
• Cardiovascular disease
• Belonging to certain racial or ethnic groups

If you have had an abnormal albumin level in your urine or have been diagnosed with kidney disease in the past, you may have repeat testing to monitor your urine albumin levels. In these cases, the doctor may request 24-hour urine samples to more precisely measure the amount of albumin.

How to get tested

Testing for urine albumin levels is normally ordered by a doctor. Your doctor can recommend either a dipstick, single urine sample, or 24-hour urine collection based on your health situation including whether you have any symptoms or risk factors for kidney disease.

Dipstick tests may be performed in a doctor’s office, health clinic, or hospital. Spot urine samples can also be collected in these medical settings. A 24-hour urine sample involves collecting all your urine in special containers over the course of a full day.

Dipstick tests are a kind of point-of-care test, which means they provide results on-site and without having to send the sample to a lab. Point-of-care devices exist for measuring albumin in a spot urine sample, but these devices are not widely available. Most spot urine samples and virtually all 24-hour urine collections are analyzed by a laboratory.

Can I take the test at home?

Some types of urine albumin tests can be taken at home. At-home test kits generally fall into two categories:

• Self-test kits: Self-test kits allow you to take and analyze the sample at home. These kits are dipstick tests in which a special paper or test strip is dipped into a cup of urine that you have collected. The test strip changes color based on the amount of albumin detected.
• Self-collection kits: This type of test involves obtaining your test sample at home and then sending it to a laboratory for analysis. Almost all 24-hour urine samples require self-collection with special bags or containers provided by your doctor.

Urine albumin-to-creatinine ratio testing is not normally done at home.

There are benefits and drawbacks to each kind of urine albumin testing, so it is important to talk with your doctor about which type of test is most appropriate in your situation and whether it can be performed at home.

How much does the test cost?

The expected cost of a urine test measuring albumin will vary based on multiple factors including:

• Whether your test uses a dipstick, spot urine sample, or 24-hour urine collection
• Whether any measurements other than albumin are included
• Where the test was performed, including whether you had a point-of-care test
• Whether you have health insurance coverage

The final cost of this testing may be composed of individual charges including office visits, any technical services involved in collecting your sample, and/or laboratory analysis.

When prescribed by a doctor, insurance often covers some or all of the cost of urine albumin testing. Despite this, you may have copayments or out-of-pocket costs toward your deductible.

For the most specific information about likely costs of a urine albumin test, talk with your doctor and health insurance provider.

Taking a Urine Albumin or Albumin-to-Creatinine Ratio Test

There are three main ways that you can take a urine albumin test: a urine dipstick, a spot urine sample, or a 24-hour urine sample.

Urine dipstick and spot urine tests are one-time samples that are normally obtained in a medical office, hospital, or lab. The specific albumin-to-creatinine ratio can be determined from a spot urine sample but not a dipstick test.

A 24-hour urine test requires that you collect all the urine that you produce for one day regardless of where you are.

There are important practical considerations for taking each test, and each one has benefits and drawbacks. Your doctor can help you understand which test is recommended for you and provide instructions for taking that version of the test.

Before the test

Before your test, check with your doctor about the schedule and timing of when your urine will be collected. For spot urine samples for albumin-to-creatinine ratio tests, some doctors may prefer to get a sample from early in the morning. If you are having a repeat test, they may try to schedule your test for around the same time of day as your previous test in order to account for normal fluctuations in creatinine production.

Intense exercise can lead to a temporary boost in albumin, so check with your doctor about whether you should restrict vigorous exercise on the day before the test.

You typically do not need to fast before a urine albumin test. Eating meat can affect creatinine levels, though, so it is possible that your doctor will ask you to avoid it for one day before an albumin-to-creatinine ratio test.

If you are going to do a 24-hour urine test, you should be given special containers before you start your test. Carefully review the test instructions and bring up any questions you have with your doctor or nurse so that you make sure that you properly prepare your test sample.

During the test

For a urine dipstick test or an albumin-to-creatinine ratio test, you will need to provide a one-time urine sample.

To obtain a spot urine sample, you will take a special container to the bathroom in the doctor’s office or lab. Typically, you will be instructed to use the “clean catch” method, which includes starting to urinate in the toilet and then placing the collection cup under your urine stream.

Although not the standard for urine albumin tests, in certain circumstances your doctor may request a split urine sample, which means that you provide two different spot urine samples at different times during the day. Generally, one of these samples is done after you’ve been standing or sitting upright, and the other is done after you have been lying down for several hours.

For a 24-hour urine sample, you will be provided with containers in which you collect all of your urine. On the test day, you urinate into the toilet the first time you pee after waking up. You then collect all of your urine for the rest of that day and during your first trip to the bathroom after waking up the next day.

After the test

In all three types of tests, you urinate normally, so it is rare to have any side effects after the test is over. After providing a spot or 24-hour urine sample, you can return to all normal daily activities.

Receiving test results

If you take a urine dipstick test, results are available within a few minutes, but this test does not provide precise albumin levels. Your doctor can usually discuss the results with you during the same office visit.

If you take a spot urine test, the albumin-to-creatinine ratio is normally measured by a laboratory with results available within a few business days. Although rare, in some cases your doctor’s office will have a device that allows for albumin levels to be measured without sending your sample to a lab.

After the lab receives your 24-hour urine sample, the total albumin level will be measured, and results should be available within several business days.

For urine albumin tests that are analyzed by a lab, you may get a copy of the test report by mail or through an online health portal. Your doctor may also call or email you to address your test results.

Interpreting test results

The interpretation of your results can depend on the type of urine albumin test that you take as well as your overall health situation and the reason that the test was prescribed.

If you have a urine dipstick test, the test strip will change color a few minutes after being in contact with your urine. Based on its color, your doctor or nurse can see whether the test registered high levels of albumin.

For an albumin-to-creatinine ratio test, your result will generally be listed in milligrams of albumin per gram of creatinine (mg/g). For a 24-hour urine sample, the total grams of albumin in the full day’s sample will be shown (g/day or g/24 hours).

Albuminuria is the medical term for elevated levels of the protein albumin. In general, the following are considered to be abnormally high amounts of urine albumin:

It is important to know that neither of these conditions are based on a single test. Instead, a diagnosis of moderately or severely increased albuminuria requires elevated levels on at least two of three tests during a period of three to six months.

Identifying albuminuria is important because it can be a sign of kidney disease. Higher levels of albuminuria are associated with a faster progression of kidney problems. Albuminuria is common in conditions like diabetes and high blood pressure that can have serious negative effects on the kidneys. High urine albumin levels are also considered to be a potential risk factor for cardiovascular problems.

Not all cases of high urine albumin levels are caused by kidney problems. Vigorous exercise, urinary tract infections, fever, and various types of inflammation can lead to temporary rises in albumin levels. Repeat tests are used to diagnose albuminuria in part because of the potential for these types of conditions to influence urine albumin levels.

In general, the less albumin in the urine, the better. Increased amounts of albumin can be tied to a higher risk of cardiovascular problems even if your levels fall within the normal range.

Talk with your doctor to best understand the results of your urine albumin test. Interpreting the test requires considering your test results along with your overall health, risk factors, and symptoms. Your doctor is in the best position to review these factors and explain what they mean for your health.

Are test results accurate?

Urine albumin tests generally offer a reliable measurement that can be used by doctors to help assess kidney health.

No test is perfect, though, and each method of testing urine albumin is subject to different issues that have the potential to affect accuracy.

Urine dipstick tests are rapid, convenient, and can usually identify significant increases in albumin in the urine. However, they are less accurate with lower albumin levels and may not detect moderately increased albuminuria.

The color change on a urine dipstick provides a range rather than a precise measurement of albumin. In addition, the test result can be affected by the total urine volume in the sample, which can change the reported concentration of albumin and potentially cause inaccurate results.

A urine albumin-to-creatinine ratio test resolves some of the accuracy concerns of a dipstick test. This testing of a spot urine sample enables a more precise measurement of the albumin level. The test also measures creatinine to control for variation in urine volume.

By using the creatinine level as a gauge, a albumin-to-creatinine ratio test can in most cases dependably estimate the total amount of albumin in a full day’s worth of urine production. Studies have found that this testing, especially when done on the day’s first morning urination, is a reliable predictor of kidney disease.

In general, the urine albumin-to-creatinine ratio test proves to be quite accurate, but in individual cases, it can have drawbacks that affect its accuracy. These challenges relate to potential variability in creatinine production.

The amount of creatinine in the urine can change at different times of day as well as in response to activity and exercise, whether you have been mostly standing or sitting, and the food and drinks you have consumed. In addition, muscle mass, sex, age, and race can all influence a person’s total daily creatinine production.

The albumin-to-creatinine ratio test depends on a standard level of creatinine production that applies to most, but not all, people. If you produce more or less creatinine, your test results may either under- or overestimate the actual level of albumin and may not properly identify albuminuria.

In terms of accuracy, a 24-hour urine collection is considered to be the gold standard for measuring albumin and detecting albuminuria. Because it tests all the urine you produce during a day, this type of test can eliminate errors found in urine dipstick or albumin-to-creatinine ratio tests.

However, the 24-hour sample test also has potential drawbacks. It can be inconvenient for patients, and this often leads to difficulties in precisely collecting all of their urine during the test’s 24-hour window. If urine is over- or under-collected, it will negatively affect the accuracy of total albumin measurement.

For laboratory analysis of both spot and 24-hour urine samples, accuracy can also depend on the technique used to measure albumin. While different methods can yield distinct results, efforts are underway to better standardize albumin measurement.

Do I need follow-up tests?

If you have an abnormal result on a urine albumin test, it is common to have follow-up tests. Repeat tests are often used to check your urine albumin again. If your initial test was with a urine dipstick, your doctor may recommend an albumin-to-creatinine ratio test or a 24-hour urine collection.

When albumin is elevated, other tests may be advised to check the status of your kidneys such as an estimated glomerular filtration rate (eGFR) test or a basic metabolic panel. Because albuminuria is often associated with diabetes and cardiovascular problems, the doctor may suggest glucose testing to check your blood sugar or a lipid panel to evaluate your cholesterol levels.

When necessary, other types of blood or urine tests or imaging tests like an ultrasound may be prescribed. Less often, a biopsy of the kidney may be needed. Depending on your situation, you may be referred to another doctor including a nephrologist, who specializes in kidney disorders, or a cardiologist, who focuses on the heart and cardiovascular disease.

Questions for your doctor about test results

To improve your understanding of your urine albumin test, you can bring up some of the following questions when discussing the test result with your doctor:

• Which type of urine albumin test did I have?
• What was my result? Was it normal or abnormal?
• How do you interpret my test result? What do you think is the most likely explanation for the test result?
• Should I repeat this test? If so, how often?
• How accurate is the urine albumin test that I had?
• Do you suggest any other tests for follow-up? What are the pros and cons of the different follow-up test options?

Urine albumin tests are one kind of test of kidney health. In addition, both albumin and creatinine can be measured in other types of tests. The following sections help explain how a urine albumin or albumin-to-creatinine ratio test is different from a number of related tests.

How is a urine albumin or albumin-to-creatinine ratio test different from an albumin blood test?

The first key difference between a urine albumin test and an albumin blood test is the type of sample. As the names indicate, one test measures albumin in urine and the other in blood.

This difference is important because albumin is expected to be in the blood. In fact, it is the most prevalent protein circulating in the blood. In contrast, under normal circumstances, very little albumin should be found in the urine.

Urine albumin tests are focused primarily on detecting kidney problems while albumin blood tests are principally, although not exclusively, for detecting liver problems. Albumin is produced in the liver, so low levels can be a sign of liver disease.

How is a urine albumin-to-creatinine ratio test different from a urine protein-to-creatinine ratio test?

An albumin-to-creatinine ratio test is very similar to a protein-to-creatinine ratio test, but the latter measures albumin and all other types of proteins in the urine. In this way, the protein-to-creatinine test has a broader focus than the albumin-to-creatinine test.

A difficulty with protein-to-creatinine tests is that no single laboratory technique can precisely measure each separate type of protein. As a result, there can be more variability in test results, leading to greater use of the urine albumin-to-creatinine ratio test.

How is a urine albumin-to-creatinine ratio test different from a creatinine test?

In a urine albumin-to-creatinine ratio test, creatinine provides a method to estimate total daily albumin in the urine while using only a spot urine sample. In a creatinine test, the focus is on measuring creatinine itself.

A creatinine test may use either a blood or urine sample. Because the kidneys typically filter creatinine out of the blood, the creatinine level can be a method of assessing the condition of the kidneys.

How is a urine albumin-to-creatinine ratio test different from a creatinine clearance test?

A urine albumin-to-creatinine ratio test and a creatinine clearance test are both related to kidney health and involve measuring creatinine in the urine. However, the test procedure and the role of the creatinine measurement reflect important differences.

In a creatinine clearance test, creatinine is measured in the blood and in the urine using a 24-hour urine sample. Comparing the two values helps determine how well the kidneys are filtering creatinine out of the blood.

This is distinct from a urine albumin-to-creatinine ratio test, which includes only a spot urine sample. In this test, creatinine is not measured to assess kidney filtration. Instead, creatinine is measured to help approximate how much albumin is produced in 24 hours with only a one-time urine sample.

How is a urine albumin or albumin-to-creatinine ratio test different from an estimated glomerular filtration rate test?

The estimated glomerular filtration rate (eGFR) is an evaluation of how well the kidneys are filtering the blood. It is an important kidney function test that can provide vital information about impairment of the kidneys.

A urine albumin or albumin-to-creatinine ratio test is another way to assess the kidneys, but it is not focused solely on filtration like eGFR. In addition, while abnormal eGFR is typically a reflection of active kidney problems, detection of albuminuria can serve as a risk factor for the progression of kidney disease as well as cardiovascular problems.

These tests are often used together to detect kidney disease and determine its severity. Studies have found that combining eGFR and urine albumin tests can better predict the likelihood of serious kidney problems.

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