Urine Albumin-to-Creatinine Ratio (uACR) Explained: Unit Normalization and KDIGO Categories
Spot urine labs often report albumin in mg/L or mg/dL and creatinine in mg/dL or g/L. Learn how to normalize those units cleanly to mg/g and mg/mmol and how uACR pairs with eGFR.
How to Normalize Urine Albumin and Creatinine Units Without Unit Errors
The most common arithmetic mistake when calculating uACR by hand is dividing urine albumin in mg/L directly by urine creatinine in mg/dL without matching the volume denominator (liters vs deciliters) and mass denominator (milligrams vs grams).
To express uACR in milligrams of albumin per gram of creatinine (mg/g): first convert Urine Albumin to mg/dL (if reported in mg/L, divide by 10). Next convert Urine Creatinine to g/dL (if reported in mg/dL, divide by 1000; if reported in g/L, divide by 10). Then divide Albumin (mg/dL) by Creatinine (g/dL).
| KDIGO Category | uACR in mg/g | uACR in mg/mmol | Descriptive Term |
|---|---|---|---|
| A1 | < 30 mg/g | < 3 mg/mmol | Normal to mildly increased |
| A2 | 30 – 300 mg/g | 3 – 30 mg/mmol | Moderately increased |
| A3 | > 300 mg/g | > 30 mg/mmol | Severely increased |
Why Confirmation Over Time Matters
A single elevated spot uACR does not by itself confirm chronic kidney disease. Vigorous exercise in the preceding 24 hours, fever, urinary tract infection, menstruation, or acute illness can transiently raise urine albumin excretion.
Clinical guidelines recommend repeating first-morning void spot uACR testing over 3 or more months alongside adult eGFR assessment.
Limitations and When to Seek Medical Care
- Always review urine albumin and eGFR trends with your clinician before drawing conclusions about kidney function.
Related Calculators
Urine Albumin-to-Creatinine Ratio (uACR) Calculator
Normalize spot urine albumin and urine creatinine lab units into the standardized Urine Albumin-to-Creatinine Ratio (uACR) in both mg/g and mg/mmol, and view KDIGO A1, A2, and A3 albuminuria categories.
eGFR Calculator (2021 CKD-EPI Race-Free Equation)
Estimate kidney filtration rate in adults aged 18 years and older using the 2021 CKD-EPI race-free creatinine equation recommended by the National Kidney Foundation (NKF) and American Society of Nephrology (ASN).
Blood Pressure Calculator (Category, Pulse Pressure & MAP)
Classify an adult blood pressure reading against the 2017 ACC/AHA adult reference table and calculate Pulse Pressure (PP) and estimated Mean Arterial Pressure (MAP) in mmHg.
Frequently Asked Questions
What is 3 mg/dL urine albumin and 100 mg/dL urine creatinine in mg/g?
100 mg/dL creatinine equals 0.1 g/dL. Dividing 3 mg/dL by 0.1 g/dL equals exactly 30 mg/g (3.4 mg/mmol).
Sources and Review Information
- [S14] KDIGO / National Kidney Foundation. Urine Albumin-to-Creatinine Ratio (uACR) Albuminuria Categories in CKD (A1 <30, A2 30-300, A3 >300 mg/g). Reference Source
- [S13] Inker LA, Eneanya ND, Coresh J, et al. New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race (2021 CKD-EPI). N Engl J Med. 2021;385(19):1737-1749. Reference Source
Prepared by: GlucoBP Editorial & Engineering Team · Verification status: Formula verified against published reference; clinical review pending · Last updated: 2026-11-15