Predictive, error-compensating kinetic method for enzymatic quantification of creatinine in serum.

Area of Science:

• Biochemistry
• Clinical Chemistry
• Enzymology

Background:

• Accurate serum creatinine quantification is crucial for diagnosing kidney function.
• Traditional methods can be influenced by experimental variables affecting enzyme activity.
• A need exists for robust, reliable creatinine assays with wide linear ranges.

Purpose of the Study:

• To develop and validate an error-compensating, kinetic-based enzymatic method for serum creatinine measurement.
• To assess the method's linearity, robustness against enzyme activity changes, and agreement with established techniques.

Main Methods:

• Utilized a four-step coupled enzymatic reaction sequence involving creatinine amidohydrolase.
• Employed a first-order kinetic model to predict reaction completion from absorbance vs. time data.
• Photometric monitoring was used to quantify the product generated during the reaction.

Main Results:

• The method demonstrated a wide linear range (44 to 1326 mumol/L) for creatinine quantification.
• A twofold change in enzyme activity resulted in minimal impact (4-12%) on creatinine concentration results.
• Results showed excellent agreement with liquid chromatography (r = 0.995) across a broad concentration range (20-1800 mumol/L).

Conclusions:

• The developed predictive kinetic approach is a robust and reliable method for serum creatinine quantification.
• The assay exhibits high accuracy, a broad linear range, and resilience to variations in enzyme activity.
• This method offers a valuable alternative for clinical laboratories requiring precise creatinine measurements.