Urine Albumin/Creatinine Ratio (uACR)
Compares albumin, a protein, with creatinine in a urine sample to show whether your kidneys are letting protein leak into urine.
AI-verified against cited sources. Awaiting expert reviewAlso called uACR, UACR, ACRLOINC 9318-7
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What it is
Albumin is a protein that healthy kidneys keep in your blood. Creatinine is a waste product your kidneys release into urine at a fairly steady rate. The lab measures both in the same urine sample and divides albumin by creatinine. This corrects for how dilute or concentrated your urine is, so one spot sample works well. A higher ratio means more albumin is leaking into your urine.
Why it matters
Albumin in the urine can be an early sign of kidney damage, even when eGFR is still in the usual range. It is also linked to a higher chance of heart and blood vessel problems. KDIGO sorts the result into three categories (A1 to A3) and combines it with eGFR to describe kidney health. One result is rarely enough, since exercise, fever and infection can raise it for a short time.
If it’s high
A result of 30 mg/g (3 mg/mmol) or more means there is more albumin than usual in your urine. This can be temporary, for example after hard exercise, a fever or a urinary infection, or it can be ongoing. If it stays at 30 or above on repeat tests over at least 3 months, it meets one of the standard criteria for chronic kidney disease. Many different things can cause this, and your clinician can put it in context.
Common causes
- Recent hard exercise, fever or a urinary tract infection (usually temporary)
- Menstrual bleeding or blood in the urine when the sample was collected
- Diabetes
- High blood pressure
- Heart disease or heart failure
- Other kidney conditions
- Extra body weight
- Smoking or tobacco use, which is a risk factor for kidney disease
- Low muscle mass or low body weight, which lowers urine creatinine and can raise the ratio
What can help
- Repeating the test on a first-morning urine sample, when you are well and not having a period
- Asking your clinician what blood pressure and blood sugar targets make sense for you
- Not smoking, regular physical activity, a balanced diet and a healthy weight, which support kidney and heart health
- Asking your clinician whether any medicines or supplements you take could be relevant, and not stopping them on your own
Usual ranges
What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.
For adults: 0–30 mg/g. Source: ARUP Laboratories, Labcorp, Kidney International 105(4S):S117-S314, National Kidney Foundation, Mayo Clinic Laboratories.
- Adults (this one applies)0–30 mg/g
Sources: ARUP Laboratories, Labcorp, Kidney International 105(4S):S117-S314, National Kidney Foundation, Mayo Clinic Laboratories
See uACR by age and sex, with the U.S. survey numbers where they exist.
Wellness targets
Narrower ranges some clinicians aim for. Being outside one doesn’t mean something is wrong.
0–10 mg/g (18+). Evidence: Moderate. In the large CKD Prognosis Consortium pooled analysis used in KDIGO 2024, people with a ratio below 10 mg/g (and eGFR 90 to 104) were the lowest-risk reference group, and higher ratios were linked to more kidney, heart and other outcomes. This is observational risk data, not a treatment target. A result of 10 to 29 mg/g is still in the usual category (A1).
KDIGO 2024 albuminuria categories (mg/g)
- A1: normal to mildly increasedbelow 30 mg/g
- A2: moderately increased30 to under 300 mg/g
- A3: severely increased300 and above mg/g
KDIGO 2024 albuminuria categories (mg/mmol)
- A1: normal to mildly increasedbelow 3 mg/mmol
- A2: moderately increased3 to under 30 mg/mmol
- A3: severely increased30 and above mg/mmol
If this applies to you
uACR means a little more for some people. Open the one that fits you.
Kidney disease or at risk
Kidney damage can show up in eGFR, in urine albumin, or in both, which is why guidelines check uACR alongside eGFR. Because results vary from day to day, a high uACR is usually confirmed on repeat samples before it counts.
Prediabetes or diabetes
uACR measures albumin, a protein, in urine, which is one way kidney damage shows up. The ADA suggests checking uACR and eGFR at least once a year in everyone with type 2 diabetes and in people who have had type 1 diabetes for 5 years or more. With kidney disease, it suggests checking them 1 to 4 times a year, depending on the stage.
How common is your level?
NHANES describes the US civilian, non-institutionalized population, not a 'healthy' reference group. People with disease, on medication, fasting or not (except fasting-subsample markers), smokers and so on are all included. A percentile says where a value sits among Americans of that sex and age, not whether it is normal.
Use the left and right arrow keys to read each age. Shift moves five years.
Reference data derived from CDC/NCHS National Health and Nutrition Examination Survey (NHANES), cycles 2015-2016, 2017-March 2020 (pre-pandemic), August 2021-August 2023. Analysis by bloodtesttracker.com; not endorsed by CDC, NCHS or HHS.
Explore uACR by age and sex: every percentile as a table, with a download.
What can affect your result
- Exercise in the 24 hours before the test
- Fever, infection or a flare of heart failure
- Menstrual bleeding or blood in the urine
- Sex: females have lower urine creatinine and tend to have a higher ratio
- Body size and muscle mass, which change urine creatinine
- Diet, such as a recent meal of meat or a high-protein intake
- Time of day and sample type: a first-morning urine is preferred over a random sample
- The lab's method: albumin results can differ by more than 40% between labs
- Hard exercise in the 24 hours before the test can raise albumin temporarily.
- Fever, infection (including a urinary tract infection), a heart failure flare-up, or a sudden rise in blood pressure or blood sugar can raise the result temporarily.
- Menstrual bleeding or blood in the urine adds albumin, so collection during a period is usually avoided.
- Urine creatinine changes the ratio. Low muscle mass or low body weight (lower creatinine) can push the ratio up, while high muscle mass, a high-protein intake or exercise (higher creatinine) can push it down. Females tend to have lower creatinine than males.
- A recent meal of meat can raise urine creatinine, so you may be asked not to eat meat the day before the test.
- Dipstick tests are less accurate than a laboratory result, and KDIGO recommends confirming a positive strip with a lab test.
A first-morning urine sample (midstream) is preferred by KDIGO. A random spot sample is acceptable. Short-term effects of exercise, fever or infection are why labs ask you to avoid testing within 24 hours of them. Whether albuminuria is persistent is judged over at least 3 months.
When to talk to a clinician
Talk with a clinician if your ratio is 30 mg/g (3 mg/mmol) or higher, especially if a repeat test is also high. KDIGO lists these among the reasons for adults with chronic kidney disease to see a kidney specialist: a ratio that stays above 700 mg/g (70 mg/mmol), a ratio of 300 mg/g (30 mg/mmol) or more together with blood in the urine, or a doubling of albuminuria on repeat testing in someone who already has significantly increased albuminuria. Contact a clinician soon if you notice swelling in your legs or feet, or you are urinating much less than usual. If your lab flagged the result as urgent, follow its instructions.
Questions you could ask
- How often should I have this test, given my health conditions?
- Does my report use mg/g or mg/mmol, and which categories does the lab use?
- Should we repeat this on a first-morning sample?
- Could exercise, a recent illness or my period have affected this result?
- How does this result, along with my eGFR, affect how often I should be checked?
- Are my blood pressure and blood sugar where they should be for me?
Questions people ask
What do the categories A1, A2 and A3 mean?
They are KDIGO's three levels of urine albumin. A1 (below 30 mg/g) is normal to mildly increased, A2 (30 to 300 mg/g) is moderately increased, and A3 (above 300 mg/g) is severely increased. Some labs still use the older term 'microalbuminuria' for results in roughly the A2 range. Together with your eGFR, the category describes your kidney health.
Why does my lab say 'below 30' while another says 'below 17' for men?
Labs have used different cutoffs over time. Most now follow the single KDIGO cutoff of 30 mg/g. Some, such as Mayo Clinic Laboratories, print sex-specific limits (below 17 for males and below 25 for females). Use the range printed on your own report.
Can exercise or my period change the result?
Yes. Hard exercise, fever, infection and menstrual bleeding can all raise albumin in the urine for a short time. Labs ask you to avoid testing in the 24 hours after exercise or illness and during your period. A first-morning sample is preferred.
How do I convert mg/g to mg/mmol?
Multiply mg/g by 0.113 to get mg/mmol. For example, 30 mg/g is about 3.4 mg/mmol. Going the other way, multiply mg/mmol by 8.84. KDIGO uses 30 mg/g and 3 mg/mmol as the approximate A2 starting points.
Is one high result enough to say I have kidney disease?
No. Chronic kidney disease needs signs of kidney damage lasting at least 3 months, and a single high ratio can come from exercise, fever or infection. Clinicians usually repeat the test within 3 to 6 months before drawing any conclusion.
Show the science and sources
Units
- 1 mg/g = 1 mg/g
- 1 mg/g = 0.1131 mg/mmol
For clinicians and researchers
uACR = urine albumin concentration ÷ urine creatinine concentration, reported in mg/g or mg/mmol (1 mg/mmol is about 8.84 mg/g; KDIGO multiplies mg/g by 0.113). Spot-urine ACR accounts for hydration and has diagnostic performance similar to 24-hour albumin excretion rate (AER), so KDIGO 2024 prefers it for initial testing, using a first-morning midstream sample. Categories are A1 below 30, A2 30 to 300 and A3 above 300 mg/g, roughly equal to AER of below 30, 30 to 300 and above 300 mg/24 h. A positive result on a random sample should be confirmed on a first-morning sample, and chronic kidney disease requires abnormal findings for at least 3 months. Labcorp notes that two of three results within 3 to 6 months should be in the abnormal range before a diagnostic threshold is considered crossed. KDIGO also advises that a doubling of ACR on a later test in people with CKD exceeds laboratory variability. Immunoturbidimetric albumin methods are standard, but there is no common reference material, so results can differ by more than 40% between labs. Urine creatinine varies with sex, muscle mass, diet and exercise (KDIGO Table 16). Some labs still print sex-specific cutoffs (Mayo: below 17 mg/g for males and below 25 mg/g for females) rather than the single KDIGO threshold. In the CKD Prognosis Consortium analysis, the median ACR was 11 mg/g (IQR 8 to 16), and the lowest-risk reference cell was ACR below 10 mg/g with eGFR 90 to 104. For children over 2 years, a first-morning ACR below 30 mg/g is usually considered normal, and orthostatic proteinuria affects an estimated 2 to 5% of adolescents.
LOINC 9318-7 (primary), 14959-1, 32294-1, 14585-4. Specimen: urine.
Sources
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease, Kidney International 105(4S):S117-S314 (2024)
- Estimated Glomerular Filtration Rate, Albuminuria, and Adverse Outcomes: An Individual-Participant Data Meta-Analysis, JAMA (CKD Prognosis Consortium) (2023)
- Albumin/Creatinine Ratio, Random Urine (test 140285), Labcorp
- Albumin-Creatinine Ratio, Urine (test 0050203), ARUP Laboratories
- A_CR - Albumin/Creatinine Ratio, Mayo Clinic Laboratories
- Urine Albumin-Creatinine Ratio (uACR), National Kidney Foundation
- Creatinine (PubChem compound 588), NCBI PubChem
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.