For individuals diagnosed with IgA nephropathy (IgAN), a condition where antibodies accumulate in the kidneys causing inflammation, kidney function can remain stable for years in some cases, while rapidly declining in others. Regular monitoring through lab tests is essential to track disease progression and ensure effective management. Two key measurements healthcare providers focus on are estimated glomerular filtration rate (eGFR) and urine protein-to-creatinine ratio (uPCR). Understanding these tests – what they mean and how they change over time – empowers you to take an active role in your care.
What Does eGFR Tell Us?
eGFR is a blood test indicating how efficiently your kidneys filter waste. As explained by Dr. Samir Parikh, a nephrologist at Ohio State University, it estimates kidney function based on milliliters (ml) of blood filtered per minute. The higher the number, the better; a score of 70 means the kidneys are functioning at roughly 70% capacity.
Here’s how healthcare providers interpret eGFR ranges:
- Greater than 60: Normal, healthy kidney function.
- 15–59: Indicates a loss of kidney function, with severity increasing as the number decreases.
- 10–15: Signals very low kidney function, potentially requiring dialysis.
Nephrologists also categorize chronic kidney disease into stages 1–5 using eGFR. The trend in eGFR is critical. While slight fluctuations between tests are normal, a consistent decline of 1-3% per year suggests disease progression requiring intervention. A drop exceeding 3% annually poses a higher risk of kidney failure.
Why Proteinuria Matters: The Role of uPCR
The urine protein-to-creatinine ratio (uPCR) measures proteinuria, the presence of excess protein in the urine. While eGFR assesses overall kidney function, uPCR specifically identifies whether the filters are damaged, allowing protein to leak through. Creatinine, a consistent waste product in urine, is used as a baseline to ensure reliable measurement.
Healthy kidneys retain proteins while filtering out waste, but damage from IgA antibody buildup causes protein leakage. Proteinuria is both a warning sign and a contributing factor: leaked protein further irritates the kidneys.
Here’s how uPCR results are interpreted:
- Under 0.2 g/g: Ideal; less than 200 mg of protein in urine.
- 0.2–0.5 g/g: May not require immediate treatment, depending on other factors.
- 0.5–1.0 g/g: Treatment is likely needed to protect the kidneys.
- 1.0–3.0 g/g: Significant leakage, requiring more aggressive treatment.
- Greater than 3.0 g/g: Severe kidney stress, potentially leading to rapid decline if untreated.
Reducing proteinuria is crucial for long-term kidney health in IgAN, as it’s often the earliest indicator of damage and can be addressed before eGFR significantly drops.
Combining eGFR and uPCR for a Clearer Picture
Healthcare providers assess both eGFR and uPCR together to understand the disease’s activity and predict future changes. Common patterns include:
- High uPCR, stable eGFR: Filters are stressed, but kidneys still function well; early intervention can prevent progression.
- High uPCR, declining eGFR: The most concerning pattern; aggressive treatment is needed to slow decline.
- Low uPCR, low eGFR: Kidneys have already lost function, but active damage is minimal; focus on protecting remaining function.
Tools like the International IgAN Prediction Tool combine these metrics with other clinical factors to estimate the risk of needing dialysis or a transplant.
Taking Control: Partnering with Your Nephrologist
To maximize your care, proactively review your lab results, identify key trends, and prepare questions for your nephrologist.
- Track your numbers: Note eGFR and uPCR changes over time to understand disease progression.
- Ask targeted questions: What is my target uPCR? Are my medications working? Is my blood pressure controlled?
- Stay informed: Educate yourself about IgAN, triggers, and available treatments.
The earlier you catch and address proteinuria, the better your chances of preserving kidney function. New treatments and therapies offer hope for managing IgAN and protecting your kidneys for years to come.
In conclusion: eGFR and uPCR are indispensable tools for monitoring IgAN. By understanding these lab results and working closely with your nephrologist, you can take an active role in slowing disease progression and preserving your kidney health.
Editorial Sources:
Taliercio JJ et al. IgA Nephropathy. Cleveland Clinic Journal of Medicine. May 24, 2023.
IgA Nephropathy (IgAN). National Kidney Foundation. April 17, 2024.
Estimated Glomerular Filtration Rate (eGFR). Cleveland Clinic. May 28, 2025.
Urine Protein Creatinine Ratio. Cleveland Clinic. December 12, 2025.
Understanding Your Lab Results. IgA Nephropathy Foundation.
Sim JJ et al. Progression of Immunoglobulin
