Albumin-To-Creatinine Ratio Underestimates True 24-Hour Albuminuria in Obesity: Clinical Relevance for Vascular Risk...

Area of Science:

• Cardiology
• Nephrology
• Endocrinology

Background:

• Albuminuria is a key indicator of endothelial dysfunction and cardiovascular risk.
• The albumin-to-creatinine ratio (ACR) is commonly used to measure urinary albumin excretion.
• In individuals with high fat-free mass (FFM), such as those with obesity, elevated urinary creatinine can lead to underestimation of albuminuria by ACR.

Purpose of the Study:

• To investigate the agreement between ACR and 24-hour urinary albumin excretion (UAE) in adults with severe obesity.
• To determine if discrepancies between ACR and UAE impact the detection of vascular dysfunction.

Main Methods:

• 140 individuals with severe obesity were enrolled.
• Albuminuria was assessed via spot ACR and 24-hour UAE.
• Vascular function was evaluated in a subgroup (n=70) using carotid-femoral pulse wave velocity (cf-PWV) and flow-mediated dilation (FMD).

Main Results:

• Elevated 24-hour UAE (≥30 mg/24h) was more common in males (35%) than females (20%), while ACR (≥30 mg/g) showed no sex difference.
• 15% of participants had elevated 24-hour UAE with normal ACR, a pattern more frequent in males with high FFM and urinary creatinine.
• Both ACR and UAE were independently associated with reduced FMD, indicating early endothelial dysfunction.

Conclusions:

• ACR may underestimate albuminuria in individuals with obesity, especially males.
• Despite potential underestimation by ACR, both ACR and UAE correlate with early endothelial dysfunction.
• 24-hour UAE may offer additional benefits for cardiovascular risk stratification when ACR is potentially underestimating albuminuria.