What this calculator does
Albumin in the urine is one of the earliest signs of kidney damage, appearing well before creatinine rises in the blood. The albumin-to-creatinine ratio detects it from a single sample rather than a timed collection.
The KDIGO categories divide the result in three. Below 30 mg/g is A1, from 30 to 300 is A2, and above 300 is A3, so an albumin of 5 mg/dL against a creatinine of 100 gives 50 mg/g and falls into A2.
The formula
Urine albumin in mg/dL is multiplied by 1,000 and divided by urine creatinine in mg/dL. Dividing by creatinine corrects for how concentrated the sample is.
| Term | Meaning |
|---|---|
| ACR | Albumin-to-creatinine ratio, in milligrams per gram. |
| KDIGO categories | A1 below 30, A2 from 30 to 300, A3 above 300 mg/g. |
| Albuminuria | Albumin appearing in urine, an early marker of kidney damage. |
The inputs explained
| Field | What to enter |
|---|---|
| Urine albumin (mg/dL) | Urine albumin in mg/dL. |
| Urine creatinine (mg/dL) | Urine creatinine in mg/dL, from the same sample. |
When to use it
Screening in diabetes
Annual albuminuria screening is standard in diabetes care.
Staging chronic kidney disease
KDIGO staging combines the albuminuria category with estimated filtration rate.
Monitoring treatment
A falling ratio indicates treatment reducing protein leak.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
What category does each albumin level fall into?
Four urine albumin levels at the same creatinine.
| Urine albumin | Albumin-to-creatinine ratio | KDIGO category |
|---|---|---|
| 1 mg/dL | 10 mg/g | A1: normal to mildly increased |
| 2 mg/dL | 20 mg/g | A1: normal to mildly increased |
| 5 mg/dL | 50 mg/g | A2: moderately increased (microalbuminuria) |
| 40 mg/dL | 400 mg/g | A3: severely increased (macroalbuminuria) |
Questions
How does this differ from the protein-to-creatinine ratio?
Albumin is one specific protein and the albumin test is far more sensitive, which is why it is preferred for early detection. The protein ratio captures all urinary protein and is used once losses are larger.
Should a single result be acted on?
No. Exercise, fever, infection and menstruation can all raise albumin transiently, so guidelines generally call for two or three abnormal results over several months before confirming persistent albuminuria.
Why is "microalbuminuria" falling out of use?
Because it implies a different, smaller kind of albumin, which is wrong. KDIGO now prefers "moderately increased albuminuria" for the A2 category, though the older term remains common.
What sample should be used?
A first morning specimen is preferred, since upright posture raises albumin excretion in some people. Where that is impractical a random sample is acceptable, with the caveat that it is less reliable.
For total urinary protein instead, see the urine protein-to-creatinine ratio calculator. For filtration rate, see the creatinine clearance calculator.