Calculate urine albumin-to-creatinine ratio (ACR) with KDIGO staging. Classifies microalbuminuria, macroalbuminuria, and CKD prognosis by GFR and albuminuria.
The Albumin-to-Creatinine Ratio (ACR) Calculator converts spot urine albumin and creatinine measurements into the standardized ACR used for kidney screening and staging. It classifies results per KDIGO guidelines (A1, A2, A3), identifies moderately and severely increased albuminuria, and can be viewed alongside eGFR for broader CKD context.
The urine ACR is widely used for detecting early kidney damage because it corrects for urine concentration by normalizing albumin to creatinine. A spot urine ACR correlates reasonably well with 24-hour albumin excretion and is far more practical for routine screening. Abnormal ACR can appear early in diabetic kidney disease and hypertensive kidney disease, often before eGFR falls.
This calculator handles multiple input units (mg/L, mg/dL for albumin; g/L, mg/dL, mmol/L for creatinine), provides the KDIGO prognosis heat map combining GFR and albuminuria categories, and includes optional sex-specific reference context for very low-range results. Use it for screening, CKD staging, and monitoring change over time.
ACR is a practical screening test because it normalizes albumin to creatinine and can be repeated over time to monitor change. It is useful for comparing one urine result with another and for placing the result into KDIGO context.
ACR (mg/g) = (Urine Albumin [mg/L]) / (Urine Creatinine [g/L]) A1: <30 mg/g | A2: 30-300 mg/g | A3: >300 mg/g Sex-specific normals: Male <17 mg/g, Female <25 mg/g
Result: ACR = 80 mg/g, A2 (Moderately increased / Microalbuminuria)
An ACR of 80 mg/g falls in the A2 category (30-300), indicating microalbuminuria. Combined with the eGFR, this determines the CKD risk level per KDIGO guidelines.
Diabetic nephropathy progresses through predictable stages: normoalbuminuria → microalbuminuria → macroalbuminuria → declining GFR → ESRD. The ACR is the most sensitive tool for detecting the transition from normal to microalbuminuria. Intervention at this stage (intensive glucose control, RAS blockade, SGLT2 inhibitors) can halt or reverse progression.
The KDIGO 2012 guidelines classify CKD risk using a 2-dimensional matrix: GFR categories (G1-G5) on one axis and albuminuria categories (A1-A3) on the other. The resulting "heat map" ranges from green (low risk) to red (very high risk) and determines monitoring frequency, treatment thresholds, and referral indications.
Beyond kidney disease, an elevated ACR independently predicts cardiovascular events, stroke, and all-cause mortality. Even microalbuminuria (A2) is associated with 2-3× increased cardiovascular risk, regardless of eGFR. This makes ACR a valuable addition to standard cardiovascular risk assessment frameworks.
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This page converts the entered urine albumin and urine creatinine values into a spot urine albumin-to-creatinine ratio in mg/g, then maps the result to the KDIGO A1, A2, and A3 albuminuria categories. When eGFR is provided, it combines the albuminuria stage with GFR stage to place the result on the standard CKD prognosis grid.
The output is intended for screening and longitudinal kidney-risk review rather than as proof of chronic kidney disease from a single sample. Temporary albuminuria can occur with exercise, infection, fever, menstruation, heart failure, and other transient conditions, so abnormal results should be confirmed the way the underlying guideline recommends.
Microalbuminuria is defined as ACR 30-300 mg/g (KDIGO A2). It indicates early kidney damage and is a marker of generalized endothelial dysfunction and cardiovascular risk.
Spot urine ACR correlates well with 24-hour albumin excretion and is far more practical. A first morning void is preferred to minimize postural and exercise effects.
ADA and KDIGO recommend annual ACR screening in all type 2 diabetes patients from diagnosis and in type 1 patients starting 5 years after diagnosis.
Yes — exercise, UTI, fever, heart failure, menstruation, and very dilute urine can transiently increase albumin. Confirm abnormal results with repeat testing on 2 of 3 samples over 3 months.
Albumin is a specific protein; proteinuria includes all proteins. ACR specifically measures albumin, which is the most sensitive marker for glomerular damage. Total protein/creatinine ratio (PCR) captures other proteins too.
Men typically excrete more creatinine due to higher muscle mass, which dilutes the ratio. Sex-specific thresholds improve sensitivity — <17 mg/g for males and <25 mg/g for females are considered truly normal.