Urine Protein-Creatinine Ratio (UPCR) Calculator
Urine Protein-Creatinine Ratio (UPCR) Calculator
Estimate daily protein excretion from a spot urine sample, useful when non-albumin proteinuria is suspected.
Urine Protein-Creatinine Ratio (UPCR)
Protein ÷ creatinine × 1000Urine protein 120 mg/dL, urine creatinine 90 mg/dL
Formula
- protein
- mg/dL, spot urine, total protein
- creatinine
- mg/dL, spot urine
- ×1000
- converts the ratio into mg protein per g creatinine
Worked example
Urine protein 120 mg/dL, urine creatinine 90 mg/dL
120 ÷ 90 × 1000 = 1333 mg/g
Between 500 and 3500 → significant proteinuria
Interpreting UPCR
| UPCR (mg/g) | Interpretation | Approx. 24h protein |
|---|---|---|
| < 150 | Normal | < 0.15 g/day |
| 150 – 500 | Mild proteinuria | 0.15 – 0.5 g/day |
| 500 – 3500 | Significant proteinuria | 0.5 – 3.5 g/day |
| > 3500 | Nephrotic range | > 3.5 g/day |
UPCR versus UACR
The urine protein-creatinine ratio measures total urinary protein — albumin plus every other protein species — normalised to creatinine, the same principle used for UACR but applied to a broader analyte. Because it is expressed in mg protein per gram of creatinine, and roughly 1 g of creatinine is excreted per 24 hours in a person with stable muscle mass, the number in mg/g approximates the 24-hour excretion in milligrams divided by 1000. A UPCR of 3500 mg/g therefore corresponds to roughly 3.5 g/day, the conventional threshold for nephrotic-range proteinuria.
UACR and UPCR are not interchangeable, and guidelines are specific about which to use. UACR is preferred for screening diabetic and hypertensive kidney disease because it is sensitive to low-level albuminuria that a dipstick or total-protein assay can miss entirely — albumin is a small fraction of total urinary protein at low concentrations, so UPCR under-detects early diabetic nephropathy. UPCR is preferred where non-albumin proteinuria is the clinical question, most notably suspected myeloma, where free light chains dominate urinary protein and would be invisible to an albumin-specific test. In known glomerular disease, either can be used to track response to treatment, provided the same test is used consistently.
Frequently asked questions
What UPCR level indicates nephrotic-range proteinuria?
Above roughly 3500 mg/g, corresponding to about 3.5 g of protein excreted per day, the conventional threshold for nephrotic-range proteinuria.
Should I use UACR or UPCR?
UACR for screening diabetic or hypertensive kidney disease, since it detects low-level albuminuria that UPCR misses. UPCR when non-albumin proteinuria matters, such as suspected myeloma with free light chains.
Why does UPCR in mg/g approximate 24-hour protein in grams?
Because a person excretes approximately 1 g of creatinine per day, protein expressed per gram of creatinine approximates protein excreted per day, avoiding a timed collection.
Can UPCR be normal with significant kidney disease?
Yes, particularly early diabetic nephropathy, where albumin rises before total protein crosses the UPCR threshold. UACR is more sensitive in that setting.
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References
- Price CP, Newall RG, Boyd JC. Use of protein:creatinine ratio measurements on random urine samples for prediction of significant proteinuria: a systematic review. Clin Chem. 2005;51(9):1577–86.
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4S):S117–S314.