What is the clinical significance of an albumin (Albumin)/creatinine (Creatinine) ratio of 33 with a normal estimated Glomerular Filtration Rate (eGFR) in a patient?

Clinical Significance of Albumin-to-Creatinine Ratio of 33 mg/g with Normal eGFR

An albumin-to-creatinine ratio (ACR) of 33 mg/g indicates moderately increased albuminuria (stage A2 chronic kidney disease) and represents early kidney damage with increased cardiovascular and renal risk, even with a normal eGFR. 1

Understanding the ACR Value

• Your ACR of 33 mg/g exceeds the normal threshold of <30 mg/g creatinine, placing you in the A2 category (moderately increased albuminuria, previously termed "microalbuminuria"). 1
• The cutoff of 30 mg/g applies to both men and women, though some evidence suggests sex-specific thresholds (>17 mg/g for men, >25 mg/g for women) may be more sensitive. 1
• This level of albuminuria is clinically significant because it represents a continuous risk marker—even values within the "moderately increased" range (30-300 mg/g) correlate with progressively higher cardiovascular and kidney disease risk. 1

Confirming the Diagnosis

You need repeat testing before establishing a definitive diagnosis of chronic kidney disease:

• Two of three urine specimens collected over 3-6 months should show ACR ≥30 mg/g to confirm persistent albuminuria, due to biological variability exceeding 20% between measurements. 1
• Transient elevations can occur with exercise within 24 hours, infection, fever, heart failure, marked hyperglycemia, menstruation, or uncontrolled hypertension—these must be excluded. 1
• First morning void samples have the lowest variability (31% coefficient of variation) and are preferred for confirmation. 1

Risk Stratification with Normal eGFR

With normal eGFR (≥60 mL/min/1.73 m²) and ACR of 33 mg/g, you are classified as having stage G1 or G2 CKD with A2 albuminuria:

• This combination places you in the "yellow" risk category on the KDIGO risk stratification grid, indicating moderately increased risk for CKD progression, cardiovascular disease, and mortality. 1
• Moderately increased albuminuria is an independent risk marker for cardiovascular death, separate from eGFR. 1
• In patients with diabetes and moderately increased albuminuria, 80% can experience 10-20% annual increases in albumin excretion, with over half progressing to severely increased albuminuria (>300 mg/g) within 10-15 years. 1

Clinical Implications and Monitoring

Your monitoring frequency should be at least annually (measurements once per year minimum for yellow risk category). 1

Key actions based on this finding:

• Annual monitoring of both ACR and eGFR is essential to detect progression early. 1
• If you have diabetes, this finding has particular significance as it indicates diabetic kidney disease, typically developing after 10 years in type 1 diabetes but potentially present at diagnosis in type 2 diabetes. 1
• ACE inhibitor or ARB therapy is recommended for patients with diabetes and ACR ≥30 mg/g, regardless of blood pressure, as these medications reduce albuminuria and slow kidney disease progression. 1
• For non-diabetic patients with normal blood pressure, ACE inhibitor/ARB is not routinely recommended for primary prevention at this level. 1

Prognostic Significance

The combination of albuminuria and eGFR provides superior risk prediction compared to either measure alone:

• Even with normal eGFR, albuminuria at your level (33 mg/g) independently predicts kidney disease progression and cardiovascular events. 2, 3
• In veterans with diabetes, ACR was independently associated with increased mortality risk at all eGFR levels, particularly in older adults. 4
• Albuminuria may detect kidney dysfunction earlier than creatinine-based eGFR, especially in patients with diabetes, as subtle GFR reductions can parallel albumin excretion even in the "normal" range. 5

Important Caveats

• If you have eGFR 45-59 mL/min/1.73 m² (stage G3a) without other kidney damage markers, measuring cystatin C for confirmation may be warranted, as this represents a controversial area where disease labeling has significant implications. 1, 6
• However, with documented albuminuria (ACR 33 mg/g), you already have a marker of kidney damage, making the CKD diagnosis more straightforward regardless of eGFR level. 6
• The term "microalbuminuria" is no longer recommended; instead, use "moderately increased albuminuria" or "A2 category." 1