A urine protein-creatinine ratio (UPCR) test looks for high levels of protein in your urine, which can happen in kidney disease. Results that are higher than average may be a sign of a kidney-related issue.
Kidney disease, particularly chronic kidney disease (CKD), is a common health concern. CKD is estimated to affect 15% of adults in the United States, according to the
There are several tests that can be used to diagnose and monitor kidney disease. One of these is a urine protein-creatinine ratio (UPCR) test, which is done by collecting and analyzing a urine sample.
A UPCR test can tell a doctor if protein levels in your urine are higher than normal. Depending on your results and other symptoms, a doctor may order additional tests to better understand your kidney function.
The UPCR test uses measurements of protein and creatinine in a urine sample. The concentration of protein is divided by the concentration of creatinine to generate the result.
Creatinine is a waste product that’s made in your muscles. Creatinine in your bloodstream is eventually filtered out by your kidneys and removed from your body in urine.
Proteins can be present in urine, but they’re normally only found at low levels. A UPCR tests looks for proteinuria. This is when protein levels in your urine are higher than normal.
Typically, a urine sample for a UPCR test is collected
Normally, little protein is present in your urine. Because proteins are important for your body’s health and function, your kidneys typically don’t filter them out of your bloodstream.
But when the filtering ability of your kidneys is impaired, they become less effective at ensuring that proteins remain in the body. This means that more protein makes its way into your urine.
As such, proteinuria can be a sign that you have problems with your kidneys. The level of proteinuria is
Assessing proteinuria, such as through a UPCR test, is a part of diagnosing kidney disease. This test can also be used to check kidney disease severity and to see how effectively your treatment plan is managing your kidney disease.
UPCR in pregnancy
A doctor may also check for proteinuria using a UPCR test if you have signs of preeclampsia during pregnancy. Preeclampsia is a serious condition where you have high blood pressure and proteinuria after 20 weeks of pregnancy.
Preeclampsia affects 1 in 25 pregnancies in the United States, according to the
The
- 30 milligrams per millimole (mg/mmol) or higher
- 300 milligrams per gram (mg/g) or higher
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A 2020 review notes that there’s some variation in the cutoffs for different levels of proteinuria. Test results can also be given in different units or no units at all, depending on the lab.
The Kidney Disease: Improving Global Outcomes clinical practice guidelines from 2013 define three categories of proteinuria as follows:
- normal to mildly increased
- moderately increased
- severely increased
The table below shows the values for each category of proteinuria when measured using a UPCR test.
| Normal to mildly increased | Moderately increased | Severely increased | |
|---|---|---|---|
| UPCR in mg/mg | less than 0.15 | 0.15–0.50 | greater than 0.50 |
| UPCR in mg/mmol | less than 15 | 15–50 | greater than 50 |
| UPCR in mg/g | less than 150 | 150–500 | greater than 500 |
What does it mean if your levels are outside of the normal range?
A result on the UPCR test that’s higher than normal may mean that you have kidney disease. Kidney disease is often caused by the effects that other health conditions have on your kidneys. This may include conditions such as:
- diabetes
- high blood pressure
- heart disease
- kidney stones
- autoimmune diseases such as lupus
- cancers such as kidney cancer and multiple myeloma
- rare inherited conditions such as polycystic kidney disease
It’s also important to note that other, more benign factors can also lead to proteinuria and therefore a higher result on a UPCR test. This includes:
- dehydration
- stress
- vigorous physical activity
- having an acute illness or infection
If the values of your UPCR test are outside of the normal range, a doctor may want to order additional tests to evaluate your kidney function. This may include additional urine tests, blood tests, imaging tests, or a biopsy.
Urine tests
A urinalysis may have been done at the same time as your UPCR test. If not, a doctor may order one. Urinalysis evaluates several qualities in a urine sample, such as:
- appearance, including color and whether the urine is clear or cloudy
- how concentrated the urine is
- pH level
- levels of substances such as protein, sugar, and blood cells
- if bacteria are present
If a UPCR test suggests proteinuria, a doctor may also want to analyze a 24-hour urine sample to verify your results. A 24-hour urine sample uses urine that’s been collected over a 24-hour period as opposed to a single point in time.
Another similar test called the urine albumin-creatinine ratio (UACR) test may also be done. Albumin is an important protein that’s typically found in the blood but can leak into the urine of people with kidney problems.
Instead of measuring and comparing total protein and creatinine, the UACR test compares albumin and creatinine. A UACR test is
Blood tests
A blood sample can be used to determine the amounts of creatinine, urea, and electrolytes in your blood. Creatinine values can also be used to calculate the estimated glomerular filtration rate (eGFR), which is an estimate of how well your kidneys are filtering your blood.
Other tests
Depending on your test results and other factors, a doctor may also order further tests to evaluate your kidney health. This may include imaging tests, such as a kidney ultrasound or CT scan, or potentially a kidney biopsy.
A UPCR test can help a doctor determine if you have high levels of protein in your urine. It’s done using a urine sample collected at a single point in time.
Results are calculated by dividing the concentration of urine protein by the concentration of urine creatinine. UPCR values that are higher than normal can be a sign of kidney disease.
The UPCR test is only one test of your kidney function. If you receive a higher-than-normal value on a UPCR test, a doctor will do other tests to get a better idea of how your kidneys are working.
