Urine Albumin-to-Creatinine Ratio Guideline

Introduction to ACR

The American College of Cardiology and other guideline societies recommend using the urine albumin-to-creatinine ratio as the single most important test for detecting early kidney damage, predicting progression to kidney failure, and identifying patients at highest risk for cardiovascular disease and death 1

The ACR detects albuminuria before it becomes clinically apparent on standard dipstick testing, identifying kidney damage years before significant loss of kidney function occurs, with a strength of evidence supported by the Annals of Internal Medicine 2
The ACR independently predicts adverse outcomes, including progression to end-stage renal disease, cardiovascular events, and all-cause mortality, with the risk increasing continuously as ACR rises, as recommended by the American Heart Association 1, 3
The ACR provides a quantifiable marker to assess response to interventions, with a sustained >30% reduction in albuminuria serving as a treatment goal that correlates with improved outcomes, according to the American Diabetes Association 3

The ACR categorizes kidney damage into three prognostically distinct categories: Normal (A1) with ACR <30 mg/g, Moderately Increased (A2) with ACR 30-299 mg/g, and Severely Increased (A3) with ACR ≥300 mg/g, as defined by the National Kidney Foundation 1, 3
Note that some evidence suggests sex-specific cutoffs (>17 mg/g in men, >25 mg/g in women) may be more accurate due to differences in creatinine excretion, though the 30 mg/g threshold remains the standard recommendation, as stated by the European Renal Association 2, 1

The ACR is superior to standard protein dipsticks, which miss early albuminuria entirely, and measuring albumin without creatinine is susceptible to false-negative and false-positive results due to variations in urine concentration, as reported by the Annals of Internal Medicine 2, 1
The ACR is comparable to the total protein-to-creatinine ratio but is more sensitive for detecting early kidney damage, particularly in diabetic nephropathy, according to the American College of Cardiology 4

The ACR result directly determines management intensity, with specific recommendations for monitoring and treatment based on ACR levels and eGFR, as outlined by the American Heart Association 1
For example, patients with ACR 30-299 mg/g and eGFR ≥60 should be monitored annually and initiated on ACE inhibitor or ARB therapy targeting blood pressure ≤130/80 mmHg, as recommended by the American College of Cardiology 1