Interferences in current methods for measurements of creatinine

Area of Science:

• Clinical Chemistry
• Analytical Chemistry
• Biochemistry

Background:

• Accurate creatinine measurement is crucial for diagnosing kidney function.
• The Jaffé reaction and enzymatic methods are commonly used for creatinine determination.
• Substances in human serum can interfere with these assays, potentially leading to inaccurate results.

Purpose of the Study:

• To evaluate the interference of various compounds on creatinine determination.
• To compare interferences across the Jaffé reaction and four enzymatic methods.

Main Methods:

• Known concentrations of interfering substances (carbonyl compounds, drugs, bilirubin, etc.) were added to creatinine solutions.
• Interference was assessed using a two-point, fixed-time kinetic Jaffé reaction.
• Interference was also evaluated using four different enzymatic creatinine assays.
• Bilirubin interference was tested in both spiked normal sera and icteric patient sera.

Main Results:

• Interference levels varied significantly between methods.
• The Jaffé reaction was affected by carbonyl compounds, dopamine, cephalosporins, and bilirubin.
• Enzymatic methods showed interference from bilirubin, creatine, dopamine, ascorbic acid, and sarcosine.

Conclusions:

• Eliminating all interferences in creatinine determination remains a challenge.
• Both traditional and newer enzymatic methods are susceptible to various interfering substances.
• Further method development is needed to improve the specificity of creatinine assays.