Protein Creatinine Ratio Calculator – Urine UPCR / PCR
Calculate spot urine total protein divided by same-specimen creatinine in mg/g, mg/mmol, and mg/mg, with interpretation boundaries distinct from ACR and measured 24-hour protein.
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Formula and medical content are based on the references listed on this page. See sources, About, and Sources and Review Process.
About
This page calculates the spot urine total-protein-to-creatinine ratio (UPCR or PCR) from total protein and creatinine measured in the same spot or untimed specimen. It reports mg/mg, mg/g, and mg/mmol: three unit expressions of one ratio, not three different tests. It measures total protein rather than albumin. [1, 4]
The ratio partly reduces the effect of urine concentration or dilution, but it still depends on individual creatinine excretion. Muscle mass, body size, acute kidney injury, diet, exercise, and other factors can change the relationship between a spot ratio and timed protein excretion. This page does not convert UPCR into mg/day or a 24-hour excretion value. [1, 4]
ACR is generally preferred for initial detection of lower-level proteinuria in CKD because it measures albumin specifically. PCR answers a total-protein question and may include albumin and non-albumin proteins; it cannot calculate the albumin fraction or assign A1, A2, or A3. One PCR result cannot diagnose CKD or nephrotic syndrome or determine treatment. [1, 2]
Formula
Interpretation
| Quantity | What it represents | Calculated here |
|---|---|---|
| Urine total protein concentration | Laboratory protein concentration in the submitted specimen | Input |
| Urine creatinine concentration | Laboratory creatinine concentration in the same specimen | Input |
| UPCR mg/mg | Total protein mass divided by creatinine mass | Yes |
| UPCR mg/g | The same ratio expressed per gram creatinine | Yes |
| UPCR mg/mmol | The same ratio expressed per mmol creatinine | Yes |
| UACR / ACR | Urine albumin divided by creatinine | No |
| Timed protein excretion | Protein collected over a defined time, such as 24 hours | No |
- Quantity
- Urine total protein concentration
- What it represents
- Laboratory protein concentration in the submitted specimen
- Calculated here
- Input
- Quantity
- Urine creatinine concentration
- What it represents
- Laboratory creatinine concentration in the same specimen
- Calculated here
- Input
- Quantity
- UPCR mg/mg
- What it represents
- Total protein mass divided by creatinine mass
- Calculated here
- Yes
- Quantity
- UPCR mg/g
- What it represents
- The same ratio expressed per gram creatinine
- Calculated here
- Yes
- Quantity
- UPCR mg/mmol
- What it represents
- The same ratio expressed per mmol creatinine
- Calculated here
- Yes
- Quantity
- UACR / ACR
- What it represents
- Urine albumin divided by creatinine
- Calculated here
- No
- Quantity
- Timed protein excretion
- What it represents
- Protein collected over a defined time, such as 24 hours
- Calculated here
- No
The three UPCR outputs are unit expressions of one ratio and are not separate clinical tests. ACR requires a urine albumin result, and daily excretion requires timed collection information. This page does not turn a ratio into a diagnosis, stage, or treatment.
What this calculator computes
The calculator separately normalizes submitted total urine protein and same-specimen urine creatinine, calculates one ratio at full precision, and displays it in mg/mg, mg/g, and mg/mmol. It does not read or infer urine albumin, urine volume, collection duration, or daily creatinine excretion.
Why the same specimen matters
Protein and creatinine must describe the same urine dilution state: use values from one container and one void, not different dates, specimens, or laboratories. This requirement is visible before entry, but the calculator cannot verify specimen identity. Editing either value or changing a selected unit clears the old result.
First-morning versus random spot specimens
KDIGO generally prefers a first-morning midstream sample because biological variability is lower; a random spot sample may be used when a first-morning sample is unavailable. Follow the applicable laboratory and clinical pathway. Ginsberg 1983 was a historical study in stable adults and does not establish sampling quality for every modern population. This page cannot verify how a specimen was collected. [1, 3]
UPCR versus ACR
UPCR measures total protein; ACR measures albumin. KDIGO and NICE generally prefer ACR for initial lower-level CKD proteinuria testing because it is more sensitive to albumin. PCR may address total protein or suspected non-albumin protein, but it cannot be converted into ACR or assign A1/A2/A3. [1, 2]
Total protein and non-albumin proteins
Spot ratio versus timed urine protein
Spot PCR can correlate with timed protein excretion in some stable populations, but that relationship is not an exact individual conversion. High proteinuria, changing kidney function, collection error, and differences in creatinine excretion can reduce agreement. This page intentionally provides no mg/day or 24-hour estimate. [3, 4]
Units, conversion, precision, and display
Protein follows mg/dL × 10 or g/L × 1000 to mg/L. Creatinine mass units use the same mass paths; mmol/L uses the fixed software factor 113 mg/mmol. Intermediate arithmetic is not rounded. mg/mg displays four decimals; mg/g and mg/mmol display one. True zero protein remains zero, and tiny positive results do not display as false zero. These software input limits are not laboratory reference intervals.
Worked examples from the implementation
50 mg/dL protein and 100 mg/dL creatinine: 500 mg/L protein and 1000 mg/L creatinine (8.849557522123893 mmol/L) produce 0.5000 mg/mg, 500.0 mg/g, and 56.5 mg/mmol.
500 mg/L and 1000 mg/L: the same physical concentrations reproduce 0.5000 mg/mg, 500.0 mg/g, and 56.5 mg/mmol.
0.5 g/L and 1 g/L: mass-unit normalization reproduces the same three displays.
500 mg/L protein and 8.849557522123893 mmol/L creatinine: the amount-concentration path normalizes to the same values and displays.
0 mg/L protein and 1000 mg/L creatinine: the arithmetic is 0.0000 mg/mg, 0.0 mg/g, and 0.0 mg/mmol. This does not prove the absence of kidney disease or another urine abnormality.
These examples audit implementation, units, and display behavior. They are not patient diagnoses or 24-hour excretion estimates.
KDIGO PCR relationships are static reference context
| Approximate PCR | Equivalent expression | Source context |
|---|---|---|
| <150 mg/g | <15 mg/mmol | Normal-to-mild total-protein relationship |
| 150–500 mg/g | 15–50 mg/mmol | Moderate total-protein relationship |
| >500 mg/g | >50 mg/mmol | Severe total-protein relationship |
- Approximate PCR
- <150 mg/g
- Equivalent expression
- <15 mg/mmol
- Source context
- Normal-to-mild total-protein relationship
- Approximate PCR
- 150–500 mg/g
- Equivalent expression
- 15–50 mg/mmol
- Source context
- Moderate total-protein relationship
- Approximate PCR
- >500 mg/g
- Equivalent expression
- >50 mg/mmol
- Source context
- Severe total-protein relationship
KDIGO presents these as approximate relationships between total-protein categories and PCR units because spot PCR depends in part on individual creatinine excretion. They are static source context, not QuickMedCalc result categories. A1, A2, and A3 are albuminuria categories based on ACR, so this total-protein calculator does not assign them. [1, 7]
Nephrotic-range proteinuria is not nephrotic syndrome
KDIGO glomerular-disease guidance defines adult nephrotic-range proteinuria as more than 3.5 g per 24 hours or PCR at least 3000 mg/g (300 mg/mmol). Nephrotic syndrome additionally depends on clinical and laboratory findings such as hypoalbuminemia; the ratio alone does not establish the syndrome. These values are shown as static source context and are never applied as a dynamic label. [7]
Creatinine excretion and ratio bias
Lower urine creatinine excretion can make a ratio relatively higher, while higher excretion can make it relatively lower. Muscle mass, body size, biological sex-related physiology, diet, exercise, and AKI can affect creatinine. A ratio reduces but does not remove urine and person-level variability, and this page makes no demographic correction. [1, 4]
Transient and preanalytical factors
Hematuria, menstruation, recent exercise, symptomatic UTI, acute illness, AKI, contamination, collection timing, changing treatment, extreme dilution or concentration, and mismatched specimens can affect interpretation. One ratio cannot distinguish persistent from transient change. [1]
Laboratory method and assay variation
Total-protein assays may respond differently to different proteins, and creatinine method or calibration can also affect the ratio. Small differences between laboratories or methods are not necessarily biological change. Trend comparisons are clearest when laboratory, method, units, and collection conditions remain consistent. This page does not validate an analyzer or assay. [4]
Pregnancy proteinuria uses a separate clinical pathway
NICE NG133 uses PCR 30 mg/mmol as a significant-proteinuria threshold in the assessment of hypertensive disorders of pregnancy, requires interpretation with a full clinical review, recommends a new sample if the result is at or above that value and the diagnosis remains uncertain, advises against a first-morning void, and does not recommend routine 24-hour collection. That sampling instruction differs from the general CKD preference for first-morning urine. [1, 6]
ACOG Practice Bulletin 222 includes a protein-to-creatinine ratio of at least 0.3 as one proteinuria criterion in the evaluation of preeclampsia. It is not equivalent to a preeclampsia diagnosis: the hypertensive and broader clinical criteria remain necessary, and preeclampsia can occur without proteinuria when specified new-onset organ dysfunction is present. NICE and ACOG expressions remain source-specific here and are not merged into a universal calculator cutoff. [8]
This calculator collects no pregnancy, blood-pressure, symptom, gestational-age, or organ-function data and applies no obstetric diagnosis or management rule. Pediatric interpretation is also pathway-specific and is not calculated here.
What the result cannot determine
The result cannot determine albumin fraction, A1/A2/A3, CKD diagnosis or stage, daily protein excretion, nephrotic syndrome, cause of proteinuria, biopsy, referral, pregnancy diagnosis, pediatric management, medicine, or treatment.
References
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease.
- NICE NG203. Chronic kidney disease: assessment and management. Recommendations 1.1.10–1.1.14.
- Ginsberg JM, Chang BS, Matarese RA, Garella S. Use of single voided urine samples to estimate quantitative proteinuria. N Engl J Med. 1983;309(25):1543–1546. PMID 6656849. DOI 10.1056/NEJM198312223092503.
- Kamińska J, et al. Diagnostic utility of protein to creatinine ratio in spot urine within routine clinical practice. Crit Rev Clin Lab Sci. 2020;57(5):345–364. PMID 32058809. DOI 10.1080/10408363.2020.1723487.
- NIH PubChem. Creatinine, CID 588. Molecular weight approximately 113.12 g/mol.
- NICE NG133. Hypertension in pregnancy: diagnosis and management. Assessment of proteinuria in hypertensive disorders of pregnancy.
- KDIGO 2021 Clinical Practice Guideline for the Management of Glomerular Diseases. Kidney Int. 2021;100(4S):S1–S276.
- American College of Obstetricians and Gynecologists. Gestational Hypertension and Preeclampsia. Practice Bulletin No. 222. Obstet Gynecol. 2020;135:e237–e260. Reaffirmed 2026. DOI 10.1097/AOG.0000000000003891.
FAQ
UPCR divides total urine protein by urine creatinine from the same spot specimen after unit normalization. This implementation calculates PCR mg/mmol = protein mg/L ÷ creatinine mmol/L, mg/g = mg/mmol ÷ 0.113, and mg/mg = mg/g ÷ 1000 without rounding intermediate arithmetic. It is a ratio, not measured 24-hour protein excretion.
They are unit expressions of the same protein-to-creatinine ratio. mg/mg is numerically equivalent to g/g. This implementation uses the fixed 113 mg/mmol creatinine factor, so mg/mmol = mg/g × 0.113.
Sources: [5]
KDIGO generally prefers a first-morning midstream specimen because biological variability is lower, while a random spot may be used when it is unavailable. The applicable pathway matters: NICE specifically advises against a first-morning void for proteinuria assessment in hypertensive pregnancy.
Hematuria, menstruation, exercise, symptomatic urinary infection, acute kidney injury, urine concentration, diet, muscle mass, body size, and collection conditions can affect protein or creatinine. Low creatinine excretion can relatively raise PCR, while high excretion can relatively lower it. Total-protein assays and creatinine methods can also differ between laboratories.
The implementation uses a fixed rounded conversion of 1 mmol creatinine = 113 mg, corresponding to creatinine's molecular weight of approximately 113.12 g/mol. It is a software conversion convention, not an infinitely precise natural constant or a serum-creatinine conversion.
Sources: [5]
KDIGO gives approximate total-protein relationships of less than 150 mg/g (less than 15 mg/mmol), 150–500 mg/g (15–50 mg/mmol), and more than 500 mg/g (more than 50 mg/mmol). They are static source context, not dynamic QuickMedCalc categories, and they are not the A1–A3 albuminuria categories used with ACR.
No. KDIGO glomerular-disease guidance uses adult PCR at least 3000 mg/g (300 mg/mmol) as one expression of nephrotic-range proteinuria, but nephrotic syndrome also depends on clinical and laboratory findings such as hypoalbuminemia. The calculator assigns neither label.
Sources: [7]
In hypertensive pregnancy, NICE uses PCR 30 mg/mmol as a significant-proteinuria threshold with full clinical review, a new sample when uncertainty remains, no first-morning void, and no routine 24-hour collection. ACOG includes a ratio of at least 0.3 as one proteinuria criterion, not a preeclampsia diagnosis by itself. This calculator applies neither threshold dynamically.
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Disclaimer
Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.