Albumin-Creatinine Ratio of 45 mg/g: Interpretation and Management
What This Result Means
An albumin-creatinine ratio (ACR) of 45 mg/g indicates moderately increased albuminuria (category A2), signaling early kidney damage that requires confirmation with repeat testing and immediate therapeutic intervention to prevent progression to more severe kidney disease. 1
Your result falls within the A2 category (ACR 30-299 mg/g), which represents kidney damage that is detectable before any measurable decline in kidney function occurs. 1 This level independently increases your risk for cardiovascular disease, progression to end-stage kidney disease, and all-cause mortality, even if your kidney filtration rate is currently normal. 2
Immediate Next Steps: Confirm the Diagnosis
Obtain 2 additional first-morning urine samples over the next 3-6 months to confirm persistent albuminuria—at least 2 of 3 total samples must show ACR ≥30 mg/g to establish the diagnosis. 1, 2
Why Confirmation is Critical
- Single ACR measurements can vary by 40-50% due to biological variability, hydration status, and other factors. 2, 3
- First-morning void specimens minimize variability compared to random samples. 2, 4
Exclude Transient Causes Before Confirming
Before labeling this as chronic kidney disease, rule out conditions that can temporarily elevate ACR: 1, 2
- Active urinary tract infection or fever
- Congestive heart failure exacerbation
- Marked hyperglycemia (high blood sugar)
- Menstruation
- Uncontrolled hypertension
- Vigorous exercise within 24 hours of urine collection
Instruct the patient to avoid vigorous exercise for 24 hours before each repeat collection. 1, 2
Essential Baseline Testing
Measure serum creatinine and calculate estimated glomerular filtration rate (eGFR) using the CKD-EPI equation to fully stage chronic kidney disease. 2, 5
Both ACR and eGFR are required to determine your risk category, treatment intensity, and monitoring frequency. 1 With an ACR of 45 mg/g and normal eGFR (≥60 mL/min/1.73 m²), you would be classified as stage 1 or 2 CKD with moderately increased albuminuria. 5
Pharmacologic Management: Start Immediately
Initiate an ACE inhibitor or ARB even if blood pressure is currently normal, as these agents provide kidney-protective effects beyond simple blood pressure lowering. 2, 5, 6
Blood Pressure Target
- Maintain blood pressure <130/80 mmHg. 1, 2, 6
- ACE inhibitors or ARBs should be first-line agents due to their specific antiproteinuric effects. 2, 5
Treatment Goal for Albuminuria
- Aim to reduce ACR by at least 30-50%, ideally achieving ACR <30 mg/g. 2, 4
- Sustained reduction in albuminuria is a validated surrogate marker for slowed CKD progression. 4
Important Contraindication
ACE inhibitors and ARBs are contraindicated in women of childbearing age unless using reliable contraception due to teratogenic effects. 4
Optimize Glycemic Control (If Diabetic)
If you have diabetes, intensify glycemic control targeting HbA1c <7% in most patients, as improved glucose control prevents progression of diabetic nephropathy. 1, 5
Screening Recommendations by Diabetes Type
- Type 1 diabetes: Begin albuminuria screening 5 years after diagnosis. 1
- Type 2 diabetes: Begin screening at the time of diagnosis due to uncertain disease onset. 1, 4
Cardiovascular Risk Reduction
Address cardiovascular risk factors aggressively, as moderately increased albuminuria significantly elevates cardiovascular morbidity and mortality. 2, 5, 6
Lipid Management Targets
- LDL cholesterol <100 mg/dL if diabetic, <120 mg/dL if non-diabetic. 2, 6
- Limit saturated fat to <7% of total calories. 2
Lifestyle Modifications
- Restrict dietary protein to 0.8 g/kg/day (recommended daily allowance). 2, 4
- Counsel on smoking cessation if applicable, as smoking accelerates kidney disease progression. 5
Monitoring Schedule Based on Kidney Function
| Baseline eGFR (mL/min/1.73 m²) | Monitoring Frequency for ACR & eGFR |
|---|---|
| ≥60 | Annually [2,4] |
| 45-59 | Every 6 months [2,4] |
| 30-44 | Every 3-4 months [2,4] |
| <30 | Immediate nephrology referral [2] |
Recheck ACR within 3-6 months after initiating therapy to assess treatment response. 5
When to Refer to Nephrology
Consider nephrology referral if any of the following occur: 2, 4, 5
- eGFR <30 mL/min/1.73 m²
- ACR ≥300 mg/g persistently despite therapy
- Rapid decline in kidney function or rapidly increasing albuminuria
- Refractory hypertension requiring ≥4 antihypertensive agents
- Active urinary sediment (red/white blood cells or casts)
- Uncertainty about the underlying cause of kidney disease
- In type 1 diabetes: absence of diabetic retinopathy with albuminuria suggests alternative causes 5
Common Pitfalls to Avoid
- Do not rely on a single ACR measurement—biological variability is substantial and confirmation is essential. 2, 3
- Do not delay ACE inhibitor/ARB therapy until blood pressure becomes elevated—start immediately for kidney protection. 2, 5
- Do not use standard urine dipsticks for protein—they do not detect albumin in the microalbuminuria range and will miss early kidney disease. 1, 6
- Do not measure albumin alone without creatinine—urine concentration changes can cause false results. 2