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Urine Protein/Creatinine Ratio (UPCR)

Compares the protein in a urine sample with its creatinine to estimate how much protein your kidneys are letting into your urine.

AI-verified against cited sources. Awaiting expert reviewAlso called UPCR, Uprot/CrLOINC 2890-2

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What it is

Healthy kidneys keep most protein in your blood, so only a small amount reaches your urine. The protein/creatinine ratio (UPCR) measures the total protein in a single urine sample and divides it by the creatinine in the same sample. Creatinine enters urine at a fairly steady rate, so the ratio corrects for how watery or concentrated the sample is. That makes a spot sample a practical stand-in for a 24-hour collection. Unlike the albumin/creatinine ratio (uACR), UPCR counts every kind of protein, not just albumin.

Why it matters

Protein in the urine is one of the main signals clinicians use to judge whether the kidney's filters are under strain, and it often causes no symptoms at first. Higher amounts are linked to a higher chance of kidney problems over time. KDIGO prefers the albumin-based uACR as the first test in adults. UPCR is still useful when total protein matters, because it also picks up non-albumin proteins that uACR can miss, and for children KDIGO suggests doing both. A high result is usually repeated, since exercise, fever and other short-term things can raise it.

If it’s high

A result above 150 mg/g (15 mg/mmol) means there is more protein than usual in your urine. It can be temporary or ongoing. KDIGO groups results as 150–500 mg/g (moderately increased) and above 500 mg/g (severely increased). If a high result stays high on repeat tests over at least 3 months, it can be one sign of kidney damage. Many different things can cause this, and your clinician can put it in context.

Common causes

  • Strenuous exercise, dehydration, fever, stress or a recent illness (usually temporary)
  • A urinary tract infection, or blood in the urine, including menstrual bleeding
  • Protein loss that happens only when upright (orthostatic proteinuria), which affects an estimated 2% to 5% of adolescents
  • Pregnancy
  • Diabetes
  • High blood pressure
  • Heart disease
  • Other kidney conditions
  • Low muscle mass or low body weight, which lowers urine creatinine and can raise the ratio
  • Proteins other than albumin, such as some tubular proteins or light chains, which uACR can miss

What can help

  • Repeating the test on a first-morning urine sample, when you are well and not having a period
  • Asking whether a urine albumin test (uACR) would add useful information
  • Asking what blood pressure and blood sugar targets make sense for you
  • Not smoking, regular physical activity and a balanced diet, which support kidney and heart health
  • Asking your clinician whether any medicines or supplements you take could be relevant, and not stopping them on your own

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

The usual range depends on age. Choose an age to see the one that applies.

Children and teens 4 ranges

See UPCR by age and sex, with the U.S. survey numbers where they exist.

KDIGO 2012 proteinuria categories (mg/g)

  • A1: normal to mildly increasedbelow 150 mg/g
  • A2: moderately increased150 to under 500 mg/g
  • A3: severely increased500 and above mg/g

KDIGO 2012 proteinuria categories (mg/mmol)

  • A1: normal to mildly increasedbelow 15 mg/mmol
  • A2: moderately increased15 to under 50 mg/mmol
  • A3: severely increased50 and above mg/mmol

What can affect your result

  • Exercise in the 24 hours before the test
  • Fever, infection or a urinary tract infection
  • Menstrual bleeding or blood in the urine
  • Sex: females have lower urine creatinine and tend to have a higher ratio
  • Body size and muscle mass, which change urine creatinine
  • Diet, such as a high-protein intake, which raises urine creatinine
  • Posture: some people lose protein only when upright
  • Time of day and sample type: a first-morning urine is preferred over a random sample
  • Age: newborns normally have high ratios, and thresholds differ for infants and children
  • The lab's method, which can differ between labs
  • Hard exercise, fever, a urinary tract infection, menstrual bleeding and blood in the urine can all raise the protein in the sample for reasons unrelated to long-term kidney health.
  • Urine creatinine changes the ratio. Females, people with low muscle mass or low body weight, and people with low protein intake or sudden kidney injury have lower urine creatinine, which pushes the ratio up. A high-protein intake or hard exercise raises urine creatinine and can push it down.
  • Some people lose protein only when they are upright (orthostatic proteinuria), so a first-morning sample is needed to tell it apart.
  • Mayo Clinic Laboratories asks that urine be collected before fluorescein dye (used in eye exams) is given, or at least 24 hours after.
  • Total protein methods react more strongly with albumin than with other proteins, there is no standard reference method, and results differ between labs. ARUP notes that its method tends to underestimate urinary light chains.
  • Dipstick (reagent strip) protein tests are less accurate than a laboratory ratio, and KDIGO recommends confirming a positive strip with a lab test.

KDIGO prefers a first-morning midstream sample. A random sample is acceptable if no first-morning sample is available. Reflects protein loss at the time of collection, and it can shift within a day with exercise or fever. Whether protein loss is persistent is judged over at least 3 months.

When to talk to a clinician

Talk with a clinician if your ratio is above 150 mg/g (15 mg/mmol), especially if a repeat test is also high. KDIGO lists, among the reasons for adults with chronic kidney disease to see a kidney specialist, albuminuria of 300 mg/g or more (approximately equal to a protein/creatinine ratio of 500 mg/g, or 50 mg/mmol, or more) together with blood in the urine. Contact a clinician soon if you notice swelling in your hands, feet, legs or around your eyes, foamy or bloody urine, or you are urinating much less than usual. If your lab flagged the result as urgent, follow its instructions.

Questions you could ask

  • Which unit does this lab use, and which range should I compare it with?
  • How often should this be rechecked, given my health conditions?
  • Should we repeat this on a first-morning urine sample?
  • Should I also have a urine albumin test (uACR)?
  • Could exercise, a recent illness, a period or a urinary infection have affected this sample?

Questions people ask

What is the difference between UPCR and uACR?

uACR measures only albumin, the main protein that leaks when the kidney's filters are damaged, and KDIGO prefers it as the first test in adults because its methods are better standardized. UPCR measures all protein, including non-albumin proteins that uACR can miss, and is commonly used in children. The two are not interchangeable: KDIGO treats a uACR of 300 mg/g as roughly equal to a UPCR of 500 mg/g.

Why does my lab report mg/g, g/g or mg/mmol?

They are the same ratio in different units. 1 g/g equals 1,000 mg/g, and mg/mg is the same as g/g. KDIGO converts mg/g to mg/mmol by multiplying by 0.113, so 1 mg/mmol is about 8.84 mg/g. KDIGO treats below 150 mg/g, or below 15 mg/mmol, as normal to mildly increased. Compare your result with the range in the same unit.

Can exercise or being sick change my result?

Yes. Hard exercise, fever, an infection, a period or blood in the urine can raise the protein in your sample for a short time. That is why a high result is usually repeated, ideally on a first-morning sample when you are well.

Show the science and sources

Units

  • 1 mg/g = 1 mg/g
  • 1 mg/g = 0.1131 mg/mmol
  • 1 mg/g = 0.001 g/g
  • 1 mg/g = 0.001 mg/mg

Open the UPCR unit converter

For clinicians and researchers

UPCR is the urine total protein concentration divided by the urine creatinine concentration in the same untimed sample. It corrects for dilution because creatinine excretion is fairly constant over 24 hours, and on random or early-morning samples it shows good diagnostic performance and correlation with 24-hour protein excretion (KDIGO 2024). Total protein is measured by turbidimetry or colorimetry. These methods react more strongly with albumin than with globulins and other proteins, some have interferences that cause falsely high results, and there is no reference measurement procedure or standardized reference material for urinary total protein, so between-lab variation is significant. ARUP notes that its method characteristically underestimates urinary light chains. KDIGO 2012 Table 7 relates categories: A1 PCR below 150 mg/g (15 mg/mmol), A2 150–500 mg/g (15–50 mg/mmol) and A3 above 500 mg/g (50 mg/mmol), with the links to excretion rates based on the assumption that creatinine excretion is about 1.0 g/day (10 mmol/day). KDIGO 2012 defines nephrotic-range proteinuria as a PCR above 3,500 mg/g (350 mg/mmol). KDIGO 2024 treats an ACR of 300 mg/g as approximately equivalent to a PCR of 500 mg/g, prefers uACR for initial testing of albuminuria in adults, and recommends PCR when measuring total protein, including in children, where it advises testing both PCR and ACR on a first-morning sample. Creatinine excretion varies with sex, weight, diet, exercise and acute kidney injury, so the ratio can over- or under-estimate protein loss in people whose creatinine excretion is far from average. For an exact conversion from mg/g of creatinine to mg/mmol, multiply by 0.113. Mayo Clinic Laboratories lists evaluation of kidney disease and monoclonal gammopathy (abnormal antibody proteins, which the albumin-based test can miss) as uses of its random urine protein/creatinine ratio.

LOINC 2890-2 (primary), 34366-5. Specimen: urine.

Sources

  1. KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease, Kidney International Supplements 3(1):1-150 (2013)
  2. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease, Kidney International 105(4S):S117-S314 (2024)
  3. RPTU1 - Protein/Creatinine Ratio, Random, Urine, Mayo Clinic Laboratories (via the Schneck Medical Center test catalog)
  4. Protein, Total, Urine (test 0020479), ARUP Laboratories
  5. Protein in Urine, MedlinePlus (National Library of Medicine)
  6. Creatinine (PubChem CID 588), PubChem (National Library of Medicine)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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