Can a mildly elevated urine albumin-to-creatinine ratio signal early vascular leakage and higher cardiovascular risk?

In older individuals, assessing subclinical biomarkers is essential for early cardiovascular risk stratification. While a urine albumin-to-creatinine ratio (UACR) below 30 mg/g is traditionally considered normal, sub-threshold elevations are increasingly recognized as early indicators of widespread vascular damage.

Mechanistic explanations

• Endothelial Glycocalyx Damage: Mildly elevated UACR (<30 mg/g) serves as a sensitive marker for systemic endothelial glycocalyx degradation. Disruption of this protective barrier increases systemic and glomerular capillary permeability, driving transcapillary albumin escape.
• Macrovascular Dysfunction: These subclinical UACR elevations strongly correlate with broader vascular dysfunction, independently predicting impaired brachial artery flow-mediated dilation (FMD) and reflecting systemic endothelial injury.

Clinical evidence and cardiovascular risk

• Continuous Risk Gradient: Cohort studies demonstrate that the relationship between UACR and cardiovascular risk is continuous, with no biological safety floor. "High-normal" levels (3–29 mg/g) independently predict incident cardiovascular disease and long-term mortality.
• Mortality Metrics: NHANES data show a 34% increase in cardiovascular mortality risk per 10 mg/g increment within the conventional normal range. In cohorts with hypertension or diabetes, the risk of major adverse cardiovascular events (MACE) escalates progressively once UACR exceeds 7 to 10 mg/g.

Bottom line

• Subclinical UACR elevations below 30 mg/g reflect early systemic microvascular leakage and glycocalyx damage, serving as a powerful, continuous predictor of cardiovascular events and mortality that warrants early risk-mitigation strategies.