Healthcare providers use uPCR to measure proteinuria, a medical term for excess protein in the urine. While eGFR measures how well your kidneys are working, proteinuria shows whether protein is leaking through the kidney filters.
If your uPCR numbers change unexpectedly, a 24-hour urine collection may be necessary for the most accurate measurement of proteinuria, says Parikh.
Understanding Proteinuria
The tiny filters in healthy kidneys allow only small waste products to pass through into the urine while keeping large, helpful molecules, like proteins, in your blood. When those filters are damaged, protein can leak into the urine. In IgAN, this damage occurs when IgA antibodies accumulate in the kidneys.
Proteinuria is both a warning sign and part of the problem. Having protein in your urine is a sign that the filters have already been damaged, while leaked protein can also irritate other parts of the kidneys, contributing to further damage, says Parikh. Many of the treatments used for IgAN are designed to reduce proteinuria and help protect the kidneys.
What the Numbers Mean
UPCR results are reported as grams of protein per gram of creatinine, abbreviated as g/g. You can think of these numbers in milligrams (mg). For example, a result of 1.0 g/g is roughly equal to 1,000 mg of protein leaking over a full day. The lower the uPCR number, the better. Here’s how to interpret the numbers, according to Johnson:
- Under 0.2 g/g This is often the goal. It means less than 200 mg of protein is leaking into the urine, which is considered a healthy range.
- 0.2 to 0.5 g/g You may not need treatment, depending on many factors, such as age, blood pressure, eGFR, and the medications you are taking.
- 0.5 to 1.0 g/g This level of leakage probably requires medical treatment to protect the kidneys.
- 1.0 to 3.0 g/g This range predicts that kidney function will likely decline further and definitely needs treatment.
- Greater than 3.0 g/g This is a sign of significant stress on the kidneys and may lead to rapid decline if not treated aggressively.
Why Reducing Proteinuria Is Important
“Reducing proteinuria to normal levels or the best possible level is crucial to preserving long-term kidney health in IgAN,” says Parikh. Proteinuria is an early warning sign that the kidney filters are under stress or actively inflamed, he says.
EGFR, on the other hand, usually begins to decline later, after the damage has been occurring for some time. Catching and reducing proteinuria early can help protect your eGFR from dropping down the road.
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