KDIGO Albuminuria Category (A1–A3) Calculator
KDIGO Albuminuria Category (A1–A3) Calculator
Classify a urine albumin-creatinine ratio into the KDIGO A1–A3 categories and see how it sharpens cardiovascular and renal risk at any eGFR.
KDIGO Albuminuria Category (A1–A3)
ACR → A-categoryACR 120 mg/g
KDIGO albuminuria categories (A1–A3)
mg/g ÷ 8.84 = mg/mmol
- A1
- normal to mildly increased, under 30 mg/g
- A2
- moderately increased, 30 to 300 mg/g — formerly 'microalbuminuria'
- A3
- severely increased, over 300 mg/g — formerly 'macroalbuminuria'
- mg/mmol
- mg/g ÷ 8.84, the unit used outside North America
Worked example
ACR 120 mg/g
120 is above 30 and at or below 300 mg/g → A2, moderately increased
120 ÷ 8.84 ≈ 13.6 mg/mmol
Albuminuria categories
| Category | mg/g | mg/mmol | Former term |
|---|---|---|---|
| A1 | < 30 | < 3.4 | Normal to mildly increased |
| A2 | 30 – 300 | 3.4 – 34 | Microalbuminuria |
| A3 | > 300 | > 34 | Macroalbuminuria |
Why albuminuria is graded separately from eGFR
The urine albumin-creatinine ratio corrects for how concentrated or dilute a spot urine sample happens to be, making a single untimed sample usable instead of needing a 24-hour collection. KDIGO groups the result into three categories, A1 to A3, which sit alongside — not underneath — the G1–G5 eGFR categories.
Albuminuria is an independent predictor of cardiovascular and renal outcomes at every level of eGFR, including within the normal range. A patient with an eGFR of 90 and an ACR of 250 carries materially higher risk than one with the same eGFR and an ACR of 10, and the KDIGO 'heat map' that combines the two axes shows risk rising in both directions at once. This is also why the A1–A3 boundaries are administrative conveniences rather than biological thresholds: the underlying relationship between ACR and risk is continuous, and someone at 28 mg/g is not meaningfully different from someone at 32 mg/g, even though one is labelled A1 and the other A2.
Because of that continuous relationship, trends matter more than a single category. A rising ACR within the A2 band, or a fall from A3 to A2 on treatment with an ACE inhibitor, ARB or SGLT2 inhibitor, is more informative than the category label taken in isolation.
Frequently asked questions
What is a normal albumin-creatinine ratio?
Below 30 mg/g, or about 3.4 mg/mmol. This is the A1 category. Risk still rises gradually within this range rather than switching on at the boundary.
How do I convert mg/g to mg/mmol?
Divide by 8.84. An ACR of 120 mg/g is about 13.6 mg/mmol. Laboratories outside North America usually report in mg/mmol directly.
Does albuminuria matter if the eGFR is normal?
Yes. It is an independent predictor of cardiovascular and renal outcomes at every eGFR level, including a normal one, and should not be dismissed just because the eGFR looks reassuring.
What ACR indicates nephrotic-range proteinuria?
Roughly above 2200 mg/g (about 250 mg/mmol), though this is usually confirmed with a 24-hour urine protein or a spot protein-creatinine ratio rather than albumin alone.
Related calculators
References
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4S):S117–S314.
- Matsushita K et al. Association of estimated glomerular filtration rate and albuminuria with all-cause and cardiovascular mortality. Lancet. 2010;375(9731):2073–2081.
Medical Disclaimer: The tools and content provided here are for educational and reference purposes only. They are not intended to substitute for professional medical advice, diagnosis, or treatment. Clinical decisions should always be based on the comprehensive assessment of a qualified healthcare professional.