Urine Albumin-to-Creatinine Ratio (UACR): What It Measures, Results and Preparation
A practical guide to the UACR urine test, including what it measures, when it is used, how to collect the sample, what the result means and when repeat testing may be needed.
Urine Albumin-to-Creatinine Ratio (UACR): What It Measures, Results and Preparation
A urine albumin-to-creatinine ratio, usually called UACR or ACR, is a urine test used to look for albumin leaking into the urine. It is especially useful when doctors are checking for kidney damage, including in people with diabetes or other risk factors for chronic kidney disease.
The test uses a single urine sample rather than requiring a routine 24-hour urine collection. The result is reported as a ratio, which helps account for how concentrated or diluted the urine is.
What is a UACR test?
UACR compares the amount of albumin in a urine sample with the amount of creatinine in the same sample.
Albumin is a protein that normally stays in the blood. Healthy kidneys generally prevent significant amounts of albumin from passing into the urine. When the kidney's filtering system is damaged, albumin can appear in urine.
According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), a spot urine UACR is the recommended test for assessing and monitoring urine albumin.
Why is UACR done?
A doctor may order a UACR when evaluating kidney health or monitoring a condition that can affect the kidneys.
It is commonly used in people with diabetes and may also be considered when there are other reasons to assess kidney function or kidney damage.
UACR is useful because albumin in urine can be an early sign of kidney disease, sometimes before a person develops obvious symptoms.
A UACR result is usually interpreted alongside other information, such as estimated glomerular filtration rate (eGFR), blood pressure, medical history, medications and previous test results.
What do UACR results mean?
NIDDK states that a urine albumin-to-creatinine ratio of 30 mg/g or less is considered normal, while a result above 30 mg/g may indicate kidney disease.
A result above the reference range does not automatically mean that a person has chronic kidney disease. Temporary factors can affect urine albumin, and a doctor may repeat the test to confirm whether the finding persists.
If albumin is detected in urine, the next step depends on the result, medical history and other kidney measurements.
UACR at a glance
| UACR result | General interpretation |
|---|---|
| 30 mg/g or less | Generally considered normal |
| More than 30 mg/g | May indicate increased urine albumin and needs clinical interpretation |
These values are a general guide, not a diagnosis. Always use the reference range and interpretation provided by your laboratory and doctor.
Does UACR require fasting?
Usually, no fasting is required for a UACR test.
The test uses a urine sample rather than a fasting blood sample. Follow any specific instructions provided by your doctor or diagnostic centre, particularly if UACR has been ordered alongside blood tests that require preparation.
Which urine sample is used for UACR?
A spot urine sample is generally sufficient.
NIDDK notes that the first morning urine sample is preferred because it is usually more concentrated and may improve detection of small amounts of albumin. A random urine sample can also be used when a first morning sample is not available.
A routine 24-hour urine collection is not necessary for standard UACR assessment.
Read our guide on how to collect a clean urine sample correctly before visiting a diagnostic centre.
How is the test performed?
The process is simple:
- You receive a clean urine container from the laboratory or collection centre.
- You provide the requested urine sample.
- The laboratory measures urine albumin and creatinine.
- The two measurements are used to calculate the UACR.
- Your doctor interprets the result alongside your other clinical information.
There is no blood draw involved.
Can one abnormal UACR result confirm kidney disease?
Not necessarily.
Urine albumin can vary, so an elevated result may need to be repeated. NIDDK notes that healthcare providers may repeat urine testing when albumin is found to confirm the result.
This is important because a single laboratory result should not be interpreted in isolation. Your doctor may also review eGFR, blood pressure, diabetes status, medications and previous results.
UACR vs routine urine test
A routine urine test and UACR answer different questions.
| Test | What it looks at |
|---|---|
| Routine urinalysis | Several urine characteristics, including blood, glucose, protein and signs that may suggest infection |
| Urine albumin test | Detects albumin in urine |
| UACR | Quantifies albumin relative to creatinine in a spot urine sample |
If you are looking for information about urine culture and sample collection, see our guide to urine culture tests.
When should you discuss a UACR result with a doctor?
Talk to your doctor if your report shows an elevated UACR, especially if you have diabetes, high blood pressure, known kidney disease or other kidney-related risk factors.
Your doctor can decide whether the result needs to be repeated and whether other kidney tests are appropriate.
Frequently asked questions
Is UACR a blood test?
No. UACR is a urine test. It measures albumin and creatinine in a urine sample.
Do I need to fast before a UACR test?
Usually no. However, follow the instructions from your doctor or diagnostic centre if UACR is part of a larger set of tests.
Is first-morning urine better for UACR?
It is generally preferred because it is more concentrated and can improve detection of small amounts of albumin. A random urine sample may also be acceptable.
What UACR level is considered abnormal?
NIDDK states that a UACR above 30 mg/g may indicate kidney disease. An abnormal result needs clinical interpretation and may require repeat testing.
Does an elevated UACR always mean kidney disease?
No. A single elevated result does not by itself establish a diagnosis. Your doctor may repeat the test and consider your other health information.
Where can I get a urine test?
You can use Locatemycentre to explore diagnostic centres and pathology labs in your area and compare available options before booking.
Sources
This article is for general education and is not a substitute for medical advice.