[Comparative performance of urinary creatinine excretion estimating equations].

Area of Science:

• Nephrology
• Clinical Chemistry

Background:

• 24-hour urine collection accuracy is crucial for evaluating kidney function, often assessed using urine creatinine (UCr) excretion.
• Existing UCr estimation equations have not been validated in Latin American populations.

Purpose of the Study:

• To evaluate the performance of nine established UCr/24h estimation equations in a Latin American cohort.
• To determine the most accurate formulas for estimating UCr/24h in this demographic.

Main Methods:

• Analyzed 24-hour urine collections from 181 ambulatory Latin American patients.
• Compared measured UCr/24h with estimates from nine equations (Ix, Gerber-Mann, Goldwasser, Cockcroft-Gault, Rule, Walser, Kawasaki, Tanaka, Huidobro).
• Assessed performance using Pearson correlation, Lin concordance, Bland-Altman analysis, bias, precision, and accuracy (P30).

Main Results:

• Walser, Ix, and Huidobro equations showed strong positive correlations with measured UCr/24h.
• Walser, Ix, Huidobro, Cockcroft-Gault, and Goldwasser equations demonstrated high accuracy (P30 > 85%).
• Gerber-Mann, Tanaka, Rule, and Kawasaki equations exhibited lower accuracy (P30 < 65%).

Conclusions:

• The Walser, Ix, and Huidobro equations are the most reliable for estimating 24-hour urine creatinine excretion in Latin American individuals.
• These findings provide validated tools for improved clinical assessment in this population.