What is a Microalbumin (24-hour Urine) test?
Microalbumin (24-hour urine) measures the total amount of albumin excreted in the urine over 24 hours.
Albumin is the main protein found in blood. Healthy kidneys normally prevent significant amounts of albumin from passing into the urine. When the kidney's filtering units become damaged, small amounts of albumin may begin to leak into the urine.
This test can detect and quantify increased urinary albumin excretion, which can be an early sign of kidney damage.
What is it used for?
A 24-hour urine microalbumin test may be used to:
Detect early kidney damage
Evaluate kidney involvement in diabetes
Assess kidney damage associated with high blood pressure
Monitor patients with known kidney disease
Quantify albumin loss over a complete 24-hour period
Help assess the risk of progression of chronic kidney disease
Today, a urine albumin-to-creatinine ratio (ACR) from a spot urine sample is commonly preferred for routine screening because it is much easier to collect and is less affected by urine concentration.
Why do I need a Microalbumin (24-hour Urine) test?
Your healthcare provider may request this test if you:
Have diabetes
Have hypertension
Have known or suspected kidney disease
Have an abnormal urine protein result
Need monitoring of kidney damage over time
Need a quantitative measurement of daily albumin loss
What happens during the test?
You will collect all urine produced during a 24-hour period in a special container.
A typical collection is:
In the morning, empty your bladder into the toilet and do not collect this first urine. Record the time.
Collect every urine specimen for the following 24 hours.
Store the collection according to your laboratory's instructions, usually refrigerated.
At the end of 24 hours, urinate one final time and include this specimen.
Return the container to the laboratory.
Missing even one urine specimen can make the result inaccurate.
Will I need to do anything to prepare for the test?
Usually, no fasting is required.
Continue your normal diet and fluid intake unless your healthcare provider gives you different instructions.
Avoid unusually strenuous exercise immediately before or during collection when possible, because intense exercise can temporarily increase urinary albumin.
Your healthcare provider may also consider factors such as fever, urinary tract infection, uncontrolled blood pressure, or acute illness when interpreting the result.
Are there any risks to the test?
There are no significant medical risks associated with urine collection.
The main potential problem is an incomplete or improperly timed 24-hour collection.
What do the results mean?
The result is usually reported as mg/24 hours.
A commonly used classification for urinary albumin excretion is:
Urinary albumin excretion Interpretation
<30 mg/24 h Normal to mildly increased
30–300 mg/24 h Moderately increased albuminuria
>300 mg/24 h Severely increased albuminuria
The exact terminology and reference intervals may vary slightly between laboratories.
Increased urinary albumin
An increased result may occur with:
Diabetic kidney disease
Hypertension-related kidney damage
Glomerular kidney disease
Chronic kidney disease
Cardiovascular disease and increased cardiovascular risk
A temporary increase can also occur with strenuous exercise, fever, infection, uncontrolled blood pressure, or hyperglycemia.
Therefore, an elevated result should generally be confirmed with repeat testing rather than interpreted from a single measurement.
Low or normal urinary albumin
A result below the laboratory's reference limit generally indicates that there is no significant increase in albumin excretion at the time of testing.
However, a normal result does not completely exclude kidney disease.
Important note
For routine screening, urine ACR is generally preferred over a 24-hour urine collection because it is easier for patients and provides albumin measurement relative to urine creatinine.
When a 24-hour collection is performed, urine volume and collection completeness are important. A 24-hour urine creatinine measurement may be useful for assessing whether the collection was likely complete.
Results should be interpreted together with serum creatinine, eGFR, blood pressure, diabetes status, and other urine findings.
Prefer to talk to someone first? Contact us to book.
