Short answer: The urine albumin-to-creatinine ratio (ACR or UACR, sometimes still called a 'microalbumin' test) measures how much albumin, a blood protein, leaks into the urine, relative to creatinine. Healthy kidneys let very little albumin through, so a raised ACR is an early sign of kidney stress. It is checked regularly in people with diabetes and high blood pressure, together with eGFR.
At a glance
| Measures | Albumin leaking into urine, relative to creatinine |
|---|---|
| Units | mg/g or mg/mmol |
| LOINC | 9318-7 (ACR) |
| Ordered for | Diabetes, high blood pressure, kidney follow-up, together with eGFR |
| Moves with | Exercise, fever, infection, menstruation, the time of day |
| Keep | Each result with eGFR and the date, to see the trend |
What the test measures
Dividing albumin by creatinine corrects for how concentrated the urine is, so a single spot sample (often first-morning urine) can be used instead of a 24-hour collection.
Because exercise, fever, infection and high blood sugar can raise albumin temporarily, a raised ACR is usually confirmed on two of three samples taken over a few months before it is considered persistent.
When it is ordered
Common reasons, which your doctor adapts to you:
- yearly or as advised in people with diabetes or high blood pressure;
- when eGFR is reduced or kidney disease is suspected;
- to follow treatment that protects the kidneys.
How the result is written on the report
| Result on the report | LOINC code | Usual unit | Also seen as |
|---|---|---|---|
| Albumin/Creatinine, urine | 9318-7 | mg/g | mg/mmol (÷8.84) |
| Microalbumin/Creatinine, urine | 14959-1 | mg/g | mg/mmol |
| eGFR (read together) | 98979-8 | mL/min/1.73 m² | — |
The US uses mg/g; the UK and Europe often use mg/mmol: mg/mmol = mg/g ÷ 8.84 (30 mg/g ≈ 3.4 mg/mmol).
Reading your report
International guidelines (KDIGO) use albuminuria categories A1–A3 together with eGFR categories to describe kidney health; your doctor tells you what yours means. Avoid hard exercise the day before, and tell your doctor about fever or a urinary infection, which can raise the result.
Keeping the results in your record
Scan or photograph the report in Anpheros Daily: each value is read with its unit and the laboratory's reference range, you check it, and it is stored with its LOINC code as an HL7 FHIR Observation, a format used by many hospitals and national health systems. Results from different laboratories line up on one chart over time, and the lab unit converter helps when two reports use different units. Our guide on how to read lab results explains reference ranges and flags in general; the lab results guide for a new doctor shows how to share them.
What this page does not do
It explains what the test is and how the result is written. It does not interpret your result, diagnose or recommend treatment: the meaning of a value depends on your history, your other results and how the sample was taken, and that is your doctor's job.
Related pages
- Creatinine and eGFR
- HbA1c test
- How to measure blood pressure at home and keep readings your doctor can use
Sources
Frequently asked questions
Is ACR the same as a microalbumin test?
Essentially yes: "microalbumin" is the older name. Today labs report the albumin-to-creatinine ratio.
How do I convert ACR from mg/g to mg/mmol?
Divide by 8.84. For example, 30 mg/g is about 3.4 mg/mmol.
Why is ACR repeated?
Because albumin in urine varies with exercise, fever, infection and blood sugar. Guidelines confirm a raised result on repeat samples.
Why are ACR and eGFR read together?
They show two sides of kidney health: filtering (eGFR) and leakage of protein (ACR).
Try it in Anpheros Daily
Photograph your lab report and Anpheros Daily lines up each value with its reference range, so you can compare reports from different laboratories.
How it works in the app →
Anpheros builds a medical record that the patient controls and can share with any clinic, on an HL7 FHIR R4 platform, based in the EU. These guides help you understand and organise your health; they do not replace your doctor.
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