What is the significance of a urine albumin‑creatinine ratio of 74 mg/g (microalbuminuria) with normal serum creatinine, hemoglobin A1c of 5.5 % (non‑diabetic) and blood urea nitrogen of 28 mg/dL, and how should this be managed?

Elevated Urine Albumin-Creatinine Ratio with Normal Creatinine

This patient has moderately increased albuminuria (ACR 74 mg/g) indicating early kidney damage that requires immediate intervention with ACE inhibitor or ARB therapy and aggressive cardiovascular risk factor modification, regardless of blood pressure, even though serum creatinine remains normal. 1, 2

Clinical Significance

Your ACR of 74 mg/g falls into the "moderately increased albuminuria" category (30-299 mg/g), previously called microalbuminuria. 1, 2 This finding is critically important because:

• Albuminuria indicates glomerular filtration barrier damage even when serum creatinine is normal, as these represent different aspects of kidney function—albumin excretion reflects barrier integrity while creatinine reflects filtration rate. 1

• This level of albuminuria independently predicts cardiovascular events, stroke, cognitive decline, dementia, and mortality in both diabetic and non-diabetic patients, making it a powerful cardiovascular risk marker beyond just kidney disease. 1, 3

• The slightly elevated BUN (28 mg/dL) with normal creatinine may reflect early changes in renal hemodynamics or prerenal factors, but does not negate the significance of the albuminuria. 1

• Your HbA1c of 5.5% rules out diabetes as the cause, so this albuminuria likely reflects hypertensive nephropathy, primary glomerular disease, or vascular endothelial dysfunction. 1

Confirmation Protocol

Before establishing persistent albuminuria, you must:

• Obtain 2 out of 3 first-morning void urine samples showing ACR ≥30 mg/g over a 3-6 month period to confirm persistence, as day-to-day variability is high. 1, 2, 3

• Exclude transient causes that falsely elevate ACR: active urinary tract infection, fever, congestive heart failure exacerbation, marked hyperglycemia, menstruation, uncontrolled hypertension, and vigorous exercise within 24 hours. 1, 2

Immediate Management Steps

Pharmacologic Intervention

• Start an ACE inhibitor or ARB immediately, regardless of your current blood pressure, as these agents provide specific antiproteinuric and kidney-protective effects beyond blood pressure lowering. 1, 2, 3

• Target blood pressure <130/80 mmHg if you have hypertension. 1, 2, 3

• Alternative agents include beta-blockers, non-dihydropyridine calcium channel blockers, or diuretics if ACE inhibitors/ARBs are contraindicated. 1

Cardiovascular Risk Reduction

• LDL cholesterol target <120 mg/dL (or <100 mg/dL if you develop diabetes), with saturated fat intake <7% of total calories. 2, 3

• Dietary protein restriction to 0.8 g/kg/day (the recommended daily allowance). 2

• Weight loss if BMI >30, as obesity contributes to albuminuria progression. 3

• Implement a low-salt, moderate-potassium diet to optimize blood pressure control. 3

Monitoring Schedule

• Recheck ACR and calculate eGFR annually since your kidney function is currently normal (eGFR ≥60 mL/min/1.73 m²). 2

• The therapeutic goal is to reduce ACR by at least 30-50%, ideally achieving ACR <30 mg/g, as sustained reduction in albuminuria is a validated surrogate for slowed kidney disease progression. 2

• If ACR increases to ≥300 mg/g or eGFR declines, monitoring frequency should increase to every 3-6 months. 2

When to Refer to Nephrology

Consider nephrology referral if:

• Rapid progression of albuminuria or decline in kidney function despite optimal therapy. 2

• Uncertainty about the underlying cause of albuminuria in the absence of diabetes or hypertension. 2

• eGFR falls below 30 mL/min/1.73 m². 2

• Inadequate response to ACE inhibitor/ARB therapy after 6-12 months. 2

• Refractory hypertension requiring ≥4 antihypertensive agents. 2

Critical Pitfalls to Avoid

• Do not dismiss this finding because creatinine is normal—albuminuria precedes creatinine elevation by years and represents early, potentially reversible kidney damage. 1

• Do not assume low muscle mass is causing a falsely elevated ACR—while this can occur, an ACR of 74 mg/g typically reflects true albuminuria requiring intervention. 4

• Do not delay ACE inhibitor/ARB therapy waiting for blood pressure elevation—the kidney-protective effects are independent of blood pressure lowering. 1, 2

• Do not use spot albumin measurement alone without creatinine correction, as this is susceptible to false results from urine concentration variations. 2