How often should albumin creatinine ratio (ACR) tests be ordered for patients with diabetes or hypertension?

Albumin-Creatinine Ratio Testing Frequency

For patients with diabetes or hypertension, albumin-creatinine ratio (ACR) testing should be performed at least annually, with more frequent testing every 6 months for those with established kidney disease (eGFR <60 mL/min/1.73 m² or ACR ≥30 mg/g). 1

Initial Screening Recommendations

Diabetes Patients

• Type 1 diabetes: Begin ACR screening 5 years after diagnosis 1, 2
• Type 2 diabetes: Begin ACR screening at the time of diagnosis due to uncertain disease onset 1, 2
• All diabetic patients with comorbid hypertension: Screen at least annually regardless of diabetes type 1

Hypertension Patients

• Annual ACR screening is recommended for all patients with hypertension 3

Confirmation of Abnormal Results

When an initial ACR is elevated (≥30 mg/g), confirmation testing is required due to high day-to-day variability:

• Obtain 2 out of 3 first-morning void samples showing ACR ≥30 mg/g over a 3-6 month period to confirm persistent albuminuria 2, 3
• Exclude transient causes before confirming chronic elevation: active urinary tract infection, fever, menstruation, marked hyperglycemia, uncontrolled hypertension, congestive heart failure exacerbation, and recent vigorous exercise 2, 3

However, recent evidence suggests that a single abnormal ACR (2-20 mg/mmol, equivalent to approximately 18-177 mg/g) has a positive predictive value of 96.8% for diagnosing CKD in type 2 diabetes patients, potentially reducing the need for multiple confirmatory tests 4

Risk-Stratified Monitoring Frequency

Once baseline ACR status is established, monitoring frequency should be adjusted based on both ACR level and eGFR:

Normal ACR (<30 mg/g)

• Annual monitoring for all patients with diabetes or hypertension 1, 3

Moderately Increased Albuminuria (ACR 30-299 mg/g)

• Every 6-12 months if eGFR ≥60 mL/min/1.73 m² 2, 3
• Every 6 months if eGFR 45-59 mL/min/1.73 m² 3
• Every 3-4 months if eGFR 30-44 mL/min/1.73 m² 3

Severely Increased Albuminuria (ACR ≥300 mg/g)

• Every 6 months if eGFR >60 mL/min/1.73 m² 3
• Every 3 months if eGFR 30-60 mL/min/1.73 m² 3
• Every 3-4 months if eGFR <30 mL/min/1.73 m² with ensured nephrology referral 3

Practical Implementation Considerations

Sample Collection

• First morning void samples are preferred to minimize variability (coefficient of variation 31%) 2
• Collections should ideally be at the same time of day with no food ingestion for at least 2 hours prior 2
• Spot urine samples are preferred over 24-hour collections, which are more burdensome and add little to prediction accuracy 2

Current Testing Gaps

Real-world data reveals significant underutilization: while eGFR testing rates among patients with type 2 diabetes approach 90%, ACR testing rates are only approximately 53%, with wide variation across clinical practice sites 1. Nearly two-thirds of patients likely to have albuminuria go undetected due to lack of ACR testing 1

Point-of-Care Testing

Point-of-care ACR testing may be used where laboratory access is limited or to facilitate clinical pathways, provided appropriate quality standards are maintained 1. Implementation of ACR point-of-care testing has been shown to positively affect diabetic kidney disease diagnosis and subsequent management 5

Nephrology Referral Timing

Consider nephrology referral when:

• eGFR <45 mL/min/1.73 m² 3
• ACR consistently >300 mg/g 3
• Immediate referral when eGFR <30 mL/min/1.73 m² 3