What is the proper procedure for collecting a urine sample for an Albumin to Creatinine Ratio (ACR) test in a patient with a history of diabetes, hypertension, or kidney disease?

Proper Urine Collection for ACR Testing

Collect a first morning void midstream urine sample as the preferred specimen for ACR testing in patients with diabetes, hypertension, or kidney disease. 1

Optimal Collection Timing and Method

• Obtain the first morning void specimen as this is the most accurate and reproducible sample type, minimizing biological variability from hydration status, exercise, and dietary factors 1
• Collect a midstream sample (not the initial stream) to reduce contamination 1
• If a first morning void is difficult to obtain, collect all samples at the same time of day to minimize variability 1

Pre-Collection Patient Instructions

• Ensure the patient is well-hydrated but has not ingested food within 2 hours prior to collection to reduce false elevations 1
• Instruct the patient to avoid vigorous exercise for 24 hours before collection, as exercise increases urinary albumin excretion 1
• Avoid collection during menstruation, as this falsely elevates ACR 1
• Defer testing if the patient has symptomatic urinary tract infection, hematuria, or acute illness, as these conditions artificially increase albumin excretion 1

Confirmation Protocol

• Confirm any elevated ACR (≥30 mg/g or ≥3 mg/mmol) with two additional first morning void samples collected over 3-6 months, as single measurements can vary by 40-50% 1, 2, 3
• At least 2 of 3 samples must be abnormal to establish persistent albuminuria and confirm the diagnosis 2, 3
• This confirmation step is critical before initiating treatment decisions, as transient elevations are common 3

Laboratory Handling Standards

• Samples should be analyzed fresh or stored at 4°C for up to 7 days maximum 1
• Do not freeze samples at -20°C, as this compromises albumin measurement accuracy 1
• The laboratory should report ACR (not just albumin concentration alone) to one decimal place, whether in mg/mmol or mg/g 1

Common Pitfalls to Avoid

• Do not use random untimed samples for initial testing unless first morning void is truly unavailable, as these have greater variability 1
• Do not use 24-hour timed urine collections in clinical practice—these should be reserved only for research settings 1
• Be aware that biological sex affects interpretation: females have lower urinary creatinine excretion and therefore higher ACR values for the same degree of albuminuria 1
• Recognize that high or low body weight affects urinary creatinine excretion and can cause falsely low or high ACR relative to actual albumin excretion 1

Point-of-Care Testing Considerations

• Point-of-care ACR devices may be used when laboratory access is limited, but must meet the same quality standards as laboratory testing 1
• POCT devices should detect at least 85% of patients with significant albuminuria (ACR ≥30 mg/g or ≥3 mg/mmol) to be considered acceptable 1
• Semiquantitative ACR dipsticks can be used for screening when quantitative tests are unavailable, but positive results must be confirmed with quantitative laboratory measurement 1

Monitoring Frequency

• Test ACR annually in adults with diabetes or hypertension as standard screening 1, 2
• For type 1 diabetes, begin screening 5 years after diagnosis; for type 2 diabetes, begin at diagnosis 1, 2
• Increase monitoring frequency to every 6 months if eGFR is <60 mL/min/1.73 m² or if ACR is ≥30 mg/g 1, 2