Serum Creatinine and Albumin Ratio (SCAR) or Albumin-to-Creatinine Ratio (ACR) – Quantitative
This test measures the ratio of albumin (a protein) to creatinine (a waste product) in urine to help assess kidney function and detect early kidney damage.
["Helps identify kidney issues early by checking protein loss in urine relative to kidney function."]
Key facts at a glance
- LOINC
- 35475-3
- Short code
- CDT
- Synonyms
- CDT Asialo/CDT Tetrasialo SerPl
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube (no anticoagulant) or serum separator tube (SST)
- Units
- N/A
- Ref low
- 0
- Ref high
- 0.005
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- High-performance liquid chromatography (HPLC), capillary electrophoresis, or immunoassay
- CPT
- 82542 (Chromatography, qualitative; column, multiple analytes) or 80307 (if used for alcohol abuse screening under certain payer guidelines)
- SNOMED
- 39517006
- Specimen volume
- 1-2 mL of serum
- Stability
- Stable for 7 days at 2-8°C; for longer storage, freeze at -20°C or below for up to 3 months. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 100
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 24–72 hours
- Order
- routine
Why This Test Matters for Kidney Health
Kidneys normally filter waste like creatinine from blood, but they also retain important proteins like albumin. When kidney damage occurs, albumin may leak into urine. This test helps detect early kidney problems by comparing albumin and creatinine levels, even when blood tests alone may not show changes yet.
How the Test Works
A small urine sample is collected, typically during a first-morning void. The sample is analyzed to measure albumin and creatinine concentrations. The ratio is calculated to determine protein loss relative to kidney function.
When You Might Need This Test
Doctors may order this test if you have symptoms like swelling, frequent urination, or high blood pressure, or if you have conditions like diabetes or high blood pressure that increase kidney risk. It’s also used in routine check-ups for people at higher risk of kidney disease.
What to Expect Before the Test
No special preparation is needed, but you may be asked to avoid certain medications or foods that could affect results (like large amounts of protein or certain supplements). Drink plenty of water the day before to help produce a clear urine sample.
Reference range
Asialo/tetrasialo transferrin ratio typically <0.005 (or <0.5%); values may vary by methodology and laboratory. A ratio of 0.005-0.010 is borderline; >0.010 is suggestive of carbohydrate-deficient transferrin (CDT) elevation consistent with chronic alcohol use.N/A
No fasting required. Patients should abstain from alcohol for at least 1-2 weeks prior to testing to avoid false-positive results. Recent blood transfusion, iron deficiency, or hepatic disease may affect results and should be disclosed to the laboratory.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A high albumin-to-creatinine ratio suggests kidney damage or disease, such as diabetic nephropathy or glomerulonephritis. Even mild elevations can indicate early kidney problems, which may improve with treatment if caught early. This test is particularly useful for monitoring kidney function in people with diabetes, hypertension, or a family history of kidney disease.
Short name
Albumin-to-Creatinine Ratio (ACR) or Urine Albumin-to-Creatinine Ratio
Frequently asked questions
What does an abnormal result mean?
Will I need to take any medications before or after this test?
How long will it take to get my results?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 15, 2026. · Read our editorial policy