New method to calculate creatinine generation rate using pre- and postdialysis creatinine concentrations

Area of Science:

• Biochemistry
• Nutritional Science
• Nephrology

Background:

• Creatinine (Cr) generation rate is linked to muscle mass and protein nutritional status.
• Existing methods for protein catabolic rate (PCR) can be adapted for Cr generation assessment.

Purpose of the Study:

• To develop and validate equations for calculating the intrinsic and total creatinine generation rate.
• To assess the influence of hemodialysis (HD) prescription on intrinsic Cr generation.
• To investigate the relationship between intrinsic Cr generation and age.

Main Methods:

• Modified Depner and Daugirdas method using predialysis Cr and estimated postrebound Cr concentration.
• Calculated total Cr generation rate by summing intrinsic and extrinsic Cr generation.
• Estimated extrinsic Cr generation based on PCR.
• Validated intrinsic Cr generation against a method using predialysis, post-HD Cr, and PCR.

Main Results:

• Developed equations for total and intrinsic Cr generation rate.
• The intrinsic Cr generation rate calculated by the new method closely matched validation results.
• Intrinsic Cr generation remained stable despite variations in HD prescription (blood flow, duration, dialyzer size).
• A significant inverse correlation was observed between intrinsic Cr generation rate and age in both sexes.

Conclusions:

• The developed equations provide a reliable method for estimating intrinsic Cr generation rate.
• Intrinsic Cr generation is a robust marker, independent of HD parameters.
• Age is a significant factor influencing intrinsic Cr generation, suggesting age-related changes in muscle metabolism.