What does an albumin (Albumin)/creatinine (Creatinine) ratio of 455 indicate?

Albumin/Creatinine Ratio of 455 mg/g Indicates Severely Increased Albuminuria with High Risk for Kidney Disease Progression

An albumin/creatinine ratio (ACR) of 455 mg/g indicates severely increased albuminuria (category A3), which represents significant kidney damage and places the individual at high risk for chronic kidney disease progression, cardiovascular events, and mortality. 1

Classification of Albuminuria

Albuminuria is categorized according to the Kidney Disease Improving Global Outcomes (KDIGO) guidelines as follows:

• A1 (Normal to Mildly Increased): ACR <30 mg/g (<3 mg/mmol) 1
• A2 (Moderately Increased): ACR 30-299 mg/g (3-29 mg/mmol), formerly called microalbuminuria 1
• A3 (Severely Increased): ACR ≥300 mg/g (≥30 mg/mmol), formerly called macroalbuminuria or overt nephropathy 1

Clinical Significance of ACR 455 mg/g

With an ACR of 455 mg/g:

• This value falls into category A3 (severely increased albuminuria), indicating significant kidney damage 1
• This level of albuminuria is associated with:
  • Increased risk of progression to end-stage renal disease 1
  • Higher cardiovascular morbidity and mortality 1, 2
  • Greater all-cause mortality regardless of age, though the effect is particularly strong in older adults 2

Clinical Implications and Management

Assessment and Monitoring

• Confirm the elevated ACR with repeat testing - at least 2 of 3 specimens collected within a 3-6 month period should be abnormal to establish persistent albuminuria 1
• Evaluate estimated glomerular filtration rate (eGFR) to fully stage chronic kidney disease 1
• Assess for other markers of kidney damage (hematuria, etc.) 1
• Evaluate for potential causes of kidney disease, particularly diabetes and hypertension 1

Monitoring Frequency

• With severely increased albuminuria (ACR ≥300 mg/g), monitoring should occur at least every 3-6 months 1
• If eGFR is also reduced (<60 ml/min/1.73m²), more frequent monitoring may be required 1

Treatment Considerations

• Implement blood pressure control, targeting appropriate goals based on comorbidities 1
• For patients with diabetes, optimize glycemic control 1
• Consider renin-angiotensin system blockers (ACE inhibitors or ARBs) which have shown benefit in reducing albuminuria and slowing CKD progression 1
• Aim for >30% sustained reduction in albuminuria as a treatment goal 1
• Nephrology referral is strongly recommended for patients with ACR ≥300 mg/g, especially if eGFR is also reduced 1

Common Pitfalls and Caveats

• Single ACR measurements can have up to 40-50% variability; confirmation with repeat testing is essential 1
• False elevations in ACR can occur with:
  • Urinary tract infections 3
  • Hematuria 1
  • Febrile illness 1
  • Vigorous exercise within 24 hours of collection 1
• Morning spot urine samples are preferred for ACR measurement to minimize variability 1
• The term "microalbuminuria" is no longer recommended by clinical guidelines; the preferred terminology is "moderately increased albuminuria" 1
• ACR results may vary between different laboratory methods, potentially affecting clinical interpretation in borderline cases 4