Does an elevated urine albumin/creatinine ratio indicate microvascular and endothelial injury with higher cardiovascular risk?

Microvascular permeability and barrier injury

• Glomerular filtration disruption: An elevated urine albumin/creatinine ratio (UACR) directly reflects increased glomerular microvascular permeability. Damage to the multi-layered glomerular filtration barrier—comprising fenestrated endothelial cells, the basement membrane, and podocytes—allows increased transcapillary passage of albumin.
• Systemic endothelial dysfunction: Elevated UACR is a highly sensitive, noninvasive biomarker for generalized endothelial barrier injury. Inflammatory, metabolic, or hemodynamic stressors trigger endothelial activation and degradation of the glycocalyx—a carbohydrate-rich protective luminal layer. This shedding (marked by elevated circulating levels of molecules like syndecan-1) disrupts tight junctions and diminishes the charge- and size-selective vascular barrier, causing systemic macromolecular leakage.

Cardiovascular risk and clinical implications

• Continuous cardiovascular risk: Elevated UACR is independently and strongly associated with a higher risk of cardiovascular events, stroke, and mortality. This risk functions along a continuum, escalating significantly at "high-normal" levels as low as 5.5 mg/g to 10 mg/g, well below the clinical microalbuminuria threshold of 30 mg/g.
• Independence from traditional factors: This prognostic association remains highly significant after statistical adjustment for kidney function (estimated glomerular filtration rate, or eGFR) and traditional cardiovascular risk factors, including blood pressure, lipid levels, smoking, and diabetes status.
• Demographic vulnerability: The predictive power of elevated UACR for major adverse cardiovascular events and mortality is exceptionally robust in older adults and males.

Bottom line

• An elevated UACR is a validated clinical indicator of glomerular microvascular permeability and systemic endothelial barrier injury. It serves as a powerful, independent predictor of cardiovascular risk and mortality across the entire clinical spectrum, showing clinical significance even at levels traditionally considered normal.