Serum Creatinine to Albumin Ratio (C:Alb Ratio)
This test measures the ratio of creatinine (a waste product from muscle metabolism) to albumin (a protein in your blood) in your serum. It helps assess kidney function and protein loss in urine.
["A useful tool to check kidney health and detect protein in urine."]
Key facts at a glance
- LOINC
- 30900-5
- Short code
- CAGGT
- Synonyms
- CA Titr SerPl Adult RBC Aggl
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top tube maintained at 37°C until serum separation; plasma may be collected in EDTA or heparin tubes kept warm.
- Units
- N/A
- Ref low
- 0
- Ref high
- 1
- Critical range
- 2 N/A – 7 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–120 years
- Method
- aggl-adult-rbc
- CPT
- 86157
- SNOMED
- 11502-6
- Specimen volume
- 1-2 mL of serum or plasma (minimum 0.5 mL)
- Stability
- Serum/plasma separated and stored at 2-8°C for up to 24 hours; for prolonged storage, freeze at -20°C or below. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 50
- Lipemia max
- 100
- Icterus max
- 20
- TAT
- 24–72 hours
- Order
- routine
What This Test Measures
Creatinine is a waste product filtered by the kidneys and excreted in urine. Albumin is a protein that helps maintain fluid balance in your body. The C:Alb Ratio combines these measurements to give insight into how well your kidneys are working and whether you’re losing protein through urine.
Why It Matters in Kidney Health
A high ratio may suggest kidney damage or proteinuria (protein in urine), which can indicate conditions like chronic kidney disease or nephrotic syndrome. A low ratio might indicate dehydration or other factors affecting creatinine levels.
How the Test Is Performed
A blood sample is drawn from a vein, usually in your arm. The serum (liquid part of blood after clotting) is then analyzed to determine the ratio of creatinine to albumin.
Preparation for the Test
No special preparation is needed, but you may be asked to avoid certain medications or foods that could affect results, such as certain supplements or high-protein diets, depending on your doctor’s instructions.
Reference range
Negative or <1:64 (normal adults typically show titers ≤1:16); clinically significant cold agglutinin disease typically associated with titers ≥1:64 at 4°C.N/A
No fasting required. Specimen should be collected and transported at 37°C to prevent in vitro cold agglutinin adsorption onto red blood cells, which can yield false-negative results. Avoid cold exposure during and after collection.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Creatinine-Albumin Ratio
Frequently asked questions
What does an abnormal result mean?
Can this test replace other kidney function tests?
How often should I get this test?
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 17, 2026. · Read our editorial policy