Short answer
Urine albumin-to-creatinine ratio, or UACR, compares albumin protein to creatinine in a spot urine sample. It helps detect albuminuria, which can be an early sign of kidney disease, especially in people with diabetes, high blood pressure, or chronic kidney disease risk. UACR is usually interpreted with eGFR and blood pressure, and an abnormal result is often repeated before anyone labels it persistent kidney disease.
What UACR measures
Albumin is a blood protein that healthy kidneys usually keep out of urine. Creatinine is a waste product that appears in urine at a fairly steady rate. Comparing the two helps adjust for how concentrated or dilute the urine is, which is why UACR is often preferred over a plain dipstick when the question is kidney-risk screening or monitoring.
Microalbumin is an older term for small amounts of albumin in urine. Some labs and articles still use it, but the meaning is usually the same basic question: is albumin leaking into urine when it should not be?
Result ranges and what they can mean
| Common result band | What it can mean | What usually comes next |
|---|---|---|
| Less than 30 mg/g | Often normal or low albumin excretion at that time. | Screen again at the interval recommended for your risk level. |
| 30 to 300 mg/g | Moderately increased albuminuria; early kidney damage or a temporary leak may be considered. | Repeat testing, eGFR, blood pressure review, diabetes review, and medication check. |
| More than 300 mg/g | Severely increased albuminuria and higher kidney/cardiovascular risk. | Closer follow-up, repeat confirmation, and kidney-focused management may be needed. |
| Dipstick protein positive but UACR missing | Protein is present but the albumin-specific kidney-risk picture is incomplete. | Ask whether UACR or urine protein-to-creatinine ratio should be ordered. |
What can affect UACR
- Recent hard exercise, fever, infection, dehydration, high blood sugar, and high blood pressure.
- UTI symptoms, visible blood, menstruation, or sample contamination.
- Very dilute or concentrated urine, which is why the creatinine ratio matters.
- Kidney disease, diabetes, hypertension, pregnancy-related conditions, and some medications.
- Some preparation instructions also mention avoiding heavy meat intake before the test because creatinine can shift with diet.
Who is usually screened
Early kidney disease often has no symptoms. NIDDK, MedlinePlus, CDC, and NKF all point to higher-risk groups such as people with diabetes, high blood pressure, heart disease, family history of kidney disease, smoking, obesity, or older age. In diabetes, urine albumin testing is commonly done on a regular basis because kidney damage can start before eGFR falls.
UACR is also used to monitor known kidney disease, to follow treatment, and to help sort out whether a urine protein finding is likely to be a one-time fluctuation or a persistent pattern.
What follow-up may clarify
If UACR is abnormal, the usual next step is to repeat it. MedlinePlus says clinicians often obtain two more tests over the next three to six months, and if two out of three are abnormal, early kidney disease may be present. That repeat-confirmation step matters because exercise, certain medicines, fever, and inflammation can temporarily raise albumin in urine.
Follow-up often includes eGFR, serum creatinine, blood pressure review, urinalysis, and sometimes urine protein-to-creatinine ratio if total protein is the bigger question. If the result stays high or keeps rising, kidney-focused treatment or nephrology follow-up may be appropriate.
Questions to ask
- Is this result above 30 mg/g, and does it need to be repeated before it is considered persistent?
- Should this be interpreted with eGFR, creatinine, blood pressure, and A1C or glucose?
- Could exercise, infection, fever, menstruation, dehydration, or medication have changed the result?
- Do I need a urine protein-to-creatinine ratio or urinalysis in addition to UACR?
- How often should I repeat UACR if I have diabetes, hypertension, or known kidney disease?
Frequently asked questions
What is a normal UACR?
Many labs consider less than 30 mg/g to be in the normal or low range, but reference ranges can vary a little by lab. A result above 30 mg/g is generally considered higher than normal and should be interpreted in context, especially if it is not repeated.
Why do I need to repeat a high UACR?
Because UACR can be temporarily elevated by exercise, infection, fever, inflammation, dehydration, menstruation, and some medicines. Repeating the test helps show whether the albumin leak is persistent.
Is UACR the same as total urine protein?
No. UACR focuses on albumin, while urine protein-to-creatinine ratio looks at total protein. They overlap, but they answer slightly different questions about kidney risk and protein loss.
Can diabetes or high blood pressure raise the risk of abnormal UACR?
Yes. Diabetes and high blood pressure are two of the most common reasons UACR is screened, because both can damage kidney filters before symptoms show up or eGFR falls.
Can exercise or illness change UACR temporarily?
Yes. Intense exercise, fever, recent illness, infection, dehydration, and sample contamination can all shift the result enough that repeat testing is needed before drawing a big conclusion.
What tests usually come after an abnormal UACR?
Common follow-up includes eGFR, serum creatinine, urinalysis, blood pressure review, diabetes testing, and sometimes urine protein-to-creatinine ratio or nephrology evaluation if the abnormality persists.