Plasma alkaline phosphatase assay: interconversion of results by two methods

Area of Science:

• Clinical Chemistry
• Biochemical Assays

Background:

• Alkaline phosphatase (ALP) is an enzyme crucial for various physiological processes.
• Accurate measurement of plasma ALP activity is essential for diagnosing liver and bone diseases.
• Different assay methodologies exist, necessitating comparison for clinical utility.

Purpose of the Study:

• To compare two distinct methods for measuring plasma alkaline phosphatase activity.
• To determine the correlation and establish a conversion factor between the two methods.
• To evaluate the feasibility of implementing a new ALP assay in routine clinical laboratory practice.

Main Methods:

• Comparison of a continuous-flow method using phenyl phosphate and carbonate-bicarbonate buffer with a reaction-rate analysis method using p-nitrophenyl phosphate and diethanolamine buffer.
• Statistical analysis of results to determine correlation coefficient (r).
• Consideration of potential impact of ALP isoenzyme variations on the conversion factor.

Main Results:

• High correlation (r = 0.98) was observed between the two methods across a broad range of plasma ALP activities.
• A reliable conversion factor was established to interconvert results between the methods.
• The new method, utilizing the conversion factor, was successfully implemented for routine ALP measurement without issues.

Conclusions:

• The two compared methods for plasma alkaline phosphatase measurement are highly correlated and can be interconverted using a specific factor.
• The potential influence of differing isoenzyme proportions on the conversion factor was considered.
• The validated new method serves as a reliable and efficient routine assay for plasma alkaline phosphatase in clinical chemistry laboratories.