Free urinary protein (mass concentration)
This test measures the amount of protein that appears in your urine without being filtered by your kidneys. It helps detect early kidney damage or conditions that cause protein to leak into urine.
["A simple urine test to check for kidney health by identifying protein loss."]
Key facts at a glance
- LOINC
- 14977-3
- Short code
- UFLC
- Synonyms
- BJ Protein Free Ur
- Category
- chemistry
- Sample
- urine
- Container
- Sterile, leak-proof urine container; 24-hour collection requires a large calibrated container without preservatives
- Units
- N/A
- Ref low
- 1.7
- Ref high
- 3.7
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Nephelometry
- CPT
- 83883
- SNOMED
- 313689003
- Specimen volume
- 10 mL for random urine; entire 24-hour collection for timed specimens
- Stability
- Ambient: 2 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 3 months. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–72 hours
- Order
- routine
Why This Test Matters
Kidneys normally filter waste and excess substances from your blood, including proteins. When kidney function declines, proteins can leak into urine. Detecting this early can help prevent serious kidney problems.
What to Expect Before the Test
You’ll provide a urine sample (usually a first-morning sample) in a clean container. No special preparation is needed, but avoid excessive protein-rich foods or strenuous activity 24 hours before testing.
How the Results Are Used
Your healthcare provider may use these results to diagnose or monitor conditions like kidney disease, diabetes, or other metabolic disorders affecting protein metabolism.
Common Conditions Monitored
This test is often used alongside other kidney function tests (like creatinine clearance) to assess kidney health, especially in people with diabetes, high blood pressure, or family history of kidney disease.
Reference range
Kappa free light chains: <32.9 mg/L; Lambda free light chains: <4.2 mg/L; Kappa/Lambda ratio: 1.7-3.7. 24-hour urine: Kappa <50 mg/24h; Lambda <25 mg/24h.N/A
No special preparation required. Normal hydration is recommended unless otherwise specified by the ordering physician.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated free urinary protein levels may indicate kidney damage, glomerular disease, or systemic conditions like lupus or certain cancers. Low levels may suggest dehydration or normal protein filtration. Results should be interpreted alongside clinical context and other tests.
Short name
Free urinary protein
Frequently asked questions
What does a high or low result mean?
Does diet affect this test?
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 16, 2026. · Read our editorial policy