What are the next steps for managing an elevated albumin-creatinine ratio (ACR)?

Management of Elevated Albumin-Creatinine Ratio (ACR)

For patients with an elevated albumin-creatinine ratio (ACR), management should focus on confirming the elevation through repeat testing, determining the underlying cause, implementing appropriate interventions based on ACR category and eGFR, and establishing regular monitoring based on risk stratification.

Initial Assessment and Confirmation

• Confirm the elevated ACR by obtaining 2-3 specimens within a 3-6 month period, as there is high biological variability (>20%) between measurements 1
• Rule out transient causes of elevated ACR such as exercise within 24 hours, infection, fever, congestive heart failure, marked hyperglycemia, menstruation, and marked hypertension 1
• Calculate estimated glomerular filtration rate (eGFR) using the CKD-EPI equation to assess kidney function 1
• Evaluate for other markers of kidney damage including urine sediment abnormalities, electrolyte disorders, and structural abnormalities 1

Risk Stratification Based on ACR Categories

• A1 (Normal to mildly increased): ACR <30 mg/g creatinine 1
• A2 (Moderately increased): ACR 30-300 mg/g creatinine (formerly called microalbuminuria) 1
• A3 (Severely increased): ACR >300 mg/g creatinine 1

Management Based on ACR Category and eGFR

For ACR 30-300 mg/g (A2 category):

• Initiate an ACE inhibitor or angiotensin receptor blocker (ARB) for patients with hypertension 1
• Monitor serum creatinine and potassium levels periodically when using ACE inhibitors, ARBs, or diuretics 1
• Optimize blood pressure control with target based on individual risk factors 1
• Implement lifestyle modifications including dietary sodium restriction, weight management, and physical activity 1

For ACR >300 mg/g (A3 category):

• Strongly recommended to initiate an ACE inhibitor or ARB regardless of blood pressure status 1
• More intensive monitoring of kidney function and electrolytes 1
• Consider referral to nephrology based on eGFR and rate of progression 1

For normal ACR (<30 mg/g) with normal BP and normal eGFR:

• ACE inhibitors or ARBs are not recommended for primary prevention of CKD 1
• Annual monitoring of ACR and eGFR is sufficient 1

Monitoring Frequency Based on Risk

• The frequency of monitoring should be guided by the combined assessment of GFR and albuminuria categories 1:
  • Normal or mildly decreased eGFR with normal ACR: Annual monitoring 1
  • Moderately increased ACR (30-300 mg/g): Monitor every 6 months 1
  • Severely increased ACR (>300 mg/g): Monitor every 3-6 months 1
  • eGFR <60 ml/min/1.73m² with any level of albuminuria: More frequent monitoring (2-4 times per year) 1

Criteria for Nephrology Referral

• eGFR <30 ml/min/1.73m² 1
• Uncertainty about the etiology of kidney disease 1
• Difficult management issues 1
• Rapidly progressing kidney disease (change in eGFR >20% on subsequent testing) 1
• After initiating hemodynamically active therapies (ACE inhibitors, ARBs, SGLT2 inhibitors), a reduction in eGFR >30% warrants evaluation 1

Special Considerations

• For patients with diabetes, annual ACR screening is recommended regardless of eGFR 1
• For patients with eGFR 45-59 ml/min/1.73m² without other markers of kidney damage, consider measuring cystatin C to confirm CKD diagnosis 1
• A doubling of ACR on subsequent testing exceeds laboratory variability and warrants evaluation 1
• Recent research suggests that even high-normal ACR values (>10 mg/g) may predict CKD progression in patients with type 2 diabetes 2

Long-term Management

• Regular assessment of CKD progression risk factors including cause of CKD, level of GFR, level of albuminuria, age, sex, race/ethnicity, BP, hyperglycemia, dyslipidemia, smoking, obesity, history of cardiovascular disease, and exposure to nephrotoxic agents 1
• Implement appropriate interventions for modifiable risk factors 1
• Consider using kidney failure risk prediction tools to guide decisions about timing of preparation for kidney replacement therapy 1