What is an Albumin/Creatinine Ratio (ACR) test?
This test measures the amount of albumin in your urine compared with the amount of creatinine. Albumin is a protein that is normally found in your blood. Healthy kidneys keep albumin in your blood and prevent large amounts from passing into your urine.
Creatinine is a waste product produced by normal muscle activity. Your kidneys normally remove creatinine from your blood and excrete it in urine.
The albumin/creatinine ratio (ACR) helps estimate how much albumin is being lost through your kidneys. Comparing albumin with creatinine helps account for how concentrated or diluted the urine sample is.
An ACR test can provide important information to help detect early kidney damage, assess kidney disease, and monitor kidney function, particularly in people with diabetes, high blood pressure, or other conditions that can affect the kidneys.
Other names: Urine albumin/creatinine ratio, UACR, urine ACR, microalbumin/creatinine ratio, albumin-to-creatinine ratio
What is it used for?
An ACR test may be used to help:
Detect early kidney damage
Small amounts of albumin in the urine, called albuminuria, can be an early sign of kidney damage. This may occur before other signs of reduced kidney function appear.
Screen for kidney disease
ACR testing is commonly used to screen people who are at increased risk of kidney disease, including people with:
Diabetes
High blood pressure
Cardiovascular disease
A family history of kidney disease
Other conditions that may affect the kidneys
Monitor kidney disease
If you already have albuminuria or kidney disease, repeated ACR measurements can help monitor changes over time and assess the response to treatment.
Assess kidney disease risk
Higher amounts of albumin in the urine are associated with an increased risk of chronic kidney disease and cardiovascular complications.
Why do I need an ACR test?
You may need an ACR test if:
You have diabetes and your healthcare provider wants to check for early kidney damage.
You have high blood pressure.
You have known kidney disease and your provider wants to monitor your condition.
You have other risk factors for kidney disease.
Another urine or blood test suggests that your kidneys may not be working normally.
Your healthcare provider wants to assess your risk of developing or worsening kidney disease.
What happens during an ACR test?
An ACR test usually uses a single urine sample, often a first-morning urine sample.
You will be asked to urinate into a clean container provided by your healthcare provider or laboratory. The laboratory measures the amount of urine albumin and urine creatinine and calculates the ratio between them.
Unlike a 24-hour urine collection, a routine ACR test usually requires only one urine sample.
Will I need to do anything to prepare for the test?
Usually, no special preparation or fasting is required for an ACR test.
However, some factors can temporarily increase urine albumin, including:
Strenuous exercise
Fever
Urinary tract infection
Dehydration
High blood glucose
High blood pressure
Your healthcare provider may recommend repeating the test if the result is unexpectedly high.
Are there any risks to the test?
There are no known risks associated with collecting a urine sample.
What do the results mean?
ACR is commonly reported as mg/g or mg/mmol, depending on the laboratory.
In general, for adults:
ACR Interpretation
<30 mg/g Normal to mildly increased
30–300 mg/g Moderately increased albuminuria
>300 mg/g Severely increased albuminuria
A higher ACR generally means that more albumin is leaking through the kidneys into the urine.
A high ACR
A high ACR may indicate kidney damage or an increased risk of kidney disease. Possible causes include:
Diabetic kidney disease
High blood pressure
Chronic kidney disease
Glomerular diseases
Cardiovascular disease
Other conditions affecting the kidneys
A single elevated result does not always mean that you have chronic kidney disease. Temporary increases can occur, so your healthcare provider may repeat the test to confirm persistent albuminuria.
A normal ACR
A normal ACR generally means that there is little or no abnormal albumin loss through the kidneys at the time of testing.
However, a normal ACR does not completely rule out kidney disease. Other tests, such as serum creatinine, estimated glomerular filtration rate (eGFR), urinalysis, and blood pressure, may also be needed to assess kidney health.
Important note
The ACR is not the same as measuring urine albumin alone. The ratio corrects for differences in urine concentration by comparing albumin with creatinine.
For the most accurate assessment, an elevated ACR is usually interpreted using repeat measurements over time, together with eGFR and other clinical findings.
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