Kidney test results: eGFR and uACR explained
Two numbers describe how your kidneys are doing: eGFR, a blood test estimate of how well they filter, and uACR, a urine test for albumin that leaks through when kidneys are damaged. Together they place you in a KDIGO category such as G2 A1. One result is not a diagnosis, and your doctor decides what your numbers mean for you. (NIDDK) (KDIGO, 2024)
eGFR: how well your kidneys filter
GFR is estimated from creatinine, a waste product from normal muscle breakdown that healthy kidneys remove from the blood. As kidney disease gets worse, creatinine goes up and eGFR goes down. (NIDDK) Results are reported in mL/min per 1.73 m², and labs flag values below 60 as low. (KDIGO, 2024) KDIGO 2024 groups eGFR into six categories:
| Category | eGFR | Meaning |
|---|---|---|
| G1 | 90 or higher | Normal or high (KDIGO, 2024) |
| G2 | 60 to 89 | Mildly decreased (KDIGO, 2024) |
| G3a | 45 to 59 | Mildly to moderately decreased (KDIGO, 2024) |
| G3b | 30 to 44 | Moderately to severely decreased (KDIGO, 2024) |
| G4 | 15 to 29 | Severely decreased (KDIGO, 2024) |
| G5 | Below 15 | Kidney failure (KDIGO, 2024) |
- G1 and G2 alone are not kidney disease: in KDIGO's chart, G1 or G2 with A1 is low risk and counts as no chronic kidney disease if there are no other markers of kidney damage. (KDIGO, 2024)
- Sources word it differently: the NKF and MedlinePlus say an eGFR of 60 to 89 may mean early kidney disease, and 15 to 59 may mean kidney disease. (NKF, 2026) (MedlinePlus, 2026) The NIDDK calls 60 or more the normal range. (NIDDK)
- Age matters: the NKF gives average eGFR by age of about 116 at 20 to 29, 107 at 30 to 39, 99 at 40 to 49, 93 at 50 to 59, 85 at 60 to 69 and 75 at 70 and older. (NKF, 2026) The ADA notes that the best cutoffs for diagnosis are debated in adults over 70. (ADA, 2026)
- No race in the formula: KDIGO says race should not be used to compute eGFR, and the ADA says the 2021 CKD-EPI creatinine equation should be used for everyone. (KDIGO, 2024) (ADA, 2026)
uACR: albumin in your urine
The urine albumin-to-creatinine ratio compares albumin with creatinine in one urine sample. A healthy kidney lets very little albumin through; the less albumin, the better. (NIDDK) KDIGO prefers a first-morning, midstream sample. (KDIGO, 2024)
| Category | uACR | Meaning |
|---|---|---|
| A1 | Below 30 mg/g (below 3 mg/mmol) | Normal to mildly increased (KDIGO, 2024) |
| A2 | 30 to 300 mg/g (3 to 30 mg/mmol) | Moderately increased (KDIGO, 2024) |
| A3 | Above 300 mg/g (above 30 mg/mmol) | Severely increased (KDIGO, 2024) |
The NIDDK words the cutoff as 30 mg/g or less being normal and more than 30 possibly a sign of kidney disease. (NIDDK) The ADA notes that uACR is a continuous measure: differences even within the normal range are linked with kidney and heart outcomes. (ADA, 2026) MedlinePlus says higher or rising albumin usually means kidney disease more likely to get worse faster and a higher risk of heart and blood vessel problems. (MedlinePlus, 2025)
Putting the two together
KDIGO stages chronic kidney disease by both numbers, for example G3a A2. Its chart colors each pair by risk: green for low risk, yellow for moderately increased, orange for high and red for very high risk. Lower eGFR and higher uACR both move you toward red. (KDIGO, 2024) Chronic kidney disease is defined by changes such as an eGFR below 60 or uACR of 30 or more that last more than 3 months. (KDIGO, 2024)
Why one result needs a repeat
- Confirm first: after a raised uACR or low eGFR, KDIGO says to repeat the tests to confirm. (KDIGO, 2024)
- 3 months: KDIGO says chronicity means at least 3 months, shown by past results or repeat tests within and beyond the 3-month point, and warns not to assume it from one abnormal eGFR or uACR, which could come from a short-term kidney injury. (KDIGO, 2024)
- Two of three urine samples: because uACR varies by more than 20% between samples, the ADA says two of three samples collected within 3 to 6 months should be abnormal before counting it as raised. MedlinePlus describes the same: usually two more tests in the 3 to 6 months after the first. (ADA, 2026) (MedlinePlus, 2025)
What can skew the numbers
- uACR can read high after exercise within 24 hours, with infection, fever, heart failure, very high blood sugar, menstruation, very high blood pressure or blood in the urine. (ADA, 2026) (KDIGO, 2024) MedlinePlus adds some medicines, inflammation, urinary tract and gum infections, and hepatitis. (MedlinePlus, 2025)
- Body size and sex change uACR: people who make less creatinine, such as women and people with low body weight, tend to have a higher ratio; people who make more tend to have a lower one. (KDIGO, 2024)
- Creatinine depends on muscle and diet: KDIGO lists eating disorders, body building or extreme exercise, amputation, spinal cord injury, severe obesity, low-protein, keto, vegetarian or high-protein diets and creatine supplements as reasons creatinine-based eGFR can be less accurate. (KDIGO, 2024)
- Before the test: MedlinePlus says hard exercise can raise urine albumin for a short time, you may be asked not to eat meat for a day before a uACR test, and some medicines can affect eGFR; do not stop any medicine unless your provider tells you to. (MedlinePlus, 2025) (MedlinePlus, 2026)
Cystatin C
Cystatin C is a small protein made by all nucleated cells and can also be used to estimate GFR, especially when creatinine is misleading, such as with amputation, frailty, low muscle mass or liver disease. It has its own pitfalls: inflammation, age, sex, body size, thyroid function and diabetes can affect it. (ADA, 2026) KDIGO recommends the combined creatinine and cystatin C estimate (eGFRcr-cys) when creatinine alone is less accurate and the number affects decisions, and says the GFR category should come from the combined estimate when cystatin C is available. (KDIGO, 2024)
What comes next
With diabetes, the ADA advises uACR and eGFR at least once a year for everyone with type 2 diabetes and for type 1 after 5 years. With chronic kidney disease, it advises checking both 1 to 4 times a year depending on the stage. (ADA, 2026) If you have kidney disease, the NIDDK says a stable eGFR and a stable or falling urine albumin are signs that treatment is working. (NIDDK) Your doctor decides the next step with you; this page does not give treatment or medicine advice. Who should be tested and how often: kidney disease screening.
Questions people ask
What is a normal eGFR?
The NKF says a normal eGFR in adults is usually more than 90, and that eGFR falls with age even without kidney disease: on average about 116 in your 20s, 99 in your 40s, 85 in your 60s and 75 from 70. An eGFR below 60 for more than 3 months is one of the markers KDIGO uses for chronic kidney disease. (NKF, 2026) (KDIGO, 2024)
Does one low eGFR or high uACR mean I have kidney disease?
No. KDIGO says to repeat the tests to confirm, and not to assume chronic kidney disease from a single abnormal result, because it could come from a short-term kidney injury. Chronic means the change lasts at least 3 months. For uACR, the ADA says two of three samples within 3 to 6 months should be abnormal. (KDIGO, 2024) (ADA, 2026)
What is a normal urine albumin-to-creatinine ratio?
Below 30 mg/g is the normal to mildly increased category (A1) in KDIGO 2024. The NIDDK words it as 30 mg/g or less being normal and more than 30 possibly a sign of kidney disease. (KDIGO, 2024) (NIDDK)
What can make a uACR result falsely high?
Exercise within 24 hours, infection, fever, heart failure, very high blood sugar, menstruation, very high blood pressure and blood in the urine can raise uACR without kidney damage. Your provider may repeat the test. (ADA, 2026) (KDIGO, 2024)
What is a cystatin C test?
Cystatin C is a protein in the blood that can be used with creatinine to estimate GFR. KDIGO and the ADA say the combined creatinine and cystatin C estimate is more accurate, and it helps when creatinine is misleading, for example with very low or very high muscle mass. (KDIGO, 2024) (ADA, 2026)