Can an elevated UACR indicate kidney microvascular damage even when filtration is normal?

A urine albumin-to-creatinine ratio (UACR) and filtration measures answer different clinical questions. In a 71-year-old man, elevated UACR merits attention even if creatinine-based eGFR, SDMA, or another filtration marker is normal.

Clinical interpretation

• Confirmed albuminuria supports kidney damage despite preserved filtration. UACR reflects abnormal albumin leakage across the glomerular filtration barrier and is consistent with glomerular/endothelial microvascular injury; a normal filtration marker principally indicates preserved GFR, not an intact glomerular barrier.
• Persistent UACR ≥30 mg/g with eGFR ≥60 mL/min/1.73 m² is recognized as albuminuric G1–G2 chronic kidney disease. Thus, elevated UACR and normal SDMA are clinically compatible rather than conflicting findings.

Mechanistic and cardiovascular relevance

• Albuminuria is associated with microvascular endothelial dysfunction independently of diabetes, blood pressure, and established CKD, supporting its role as a marker of vascular injury beyond filtration decline.
• In people with preserved eGFR, even UACR values of 5–9 mg/g and 10–29 mg/g were independently associated with higher risk of major adverse cardiovascular events. This makes albuminuria relevant to both renal and broader vascular risk assessment.

Confirmation and clinical context

• Do not diagnose chronic kidney disease from one elevated sample. Repeat a UACR ≥30 mg/g using a first-morning midstream urine specimen; persistence for at least 3 months is required for CKD classification.
• Exercise, infection/fever, acute illness or kidney injury, heart failure, and uncontrolled blood pressure or hyperglycemia can temporarily raise UACR. Interpretation should incorporate urinalysis, blood pressure, creatinine-based eGFR, SDMA where used, and the clinical setting.

Bottom line

• An elevated, persistent UACR can indicate renal microvascular/glomerular damage even with normal filtration markers; normal GFR does not exclude early kidney injury or associated cardiovascular risk.