The relationship between total tear protein concentrations determined by different methods and standards

Area of Science:

• Biochemistry
• Ophthalmology
• Analytical Chemistry

Background:

• Total protein concentration (TPC) in human tears exhibits significant variability depending on the assay method and standards used.
• These discrepancies arise from differing protein reactivities across various analytical techniques.
• Establishing consistent TPC measurements is crucial for accurate tear fluid analysis.

Purpose of the Study:

• To investigate the relationships and agreement between TPC values derived from different measurement methods and standards.
• To develop predictive equations for interconverting TPC values obtained by distinct assays.

Main Methods:

• Two experiments were conducted involving 45 normal subjects.
• Experiment 1: Determined TPC using Bradford and modified Lowry methods with BSA and IgG standards, establishing linear relationships.
• Experiment 2: Compared measured TPC values with those calculated using equations from Experiment 1 to assess agreement and reliability.

Main Results:

• Strong positive correlations were observed between TPC values obtained by different methods/standards.
• Linear equations accurately described the relationships between TPC measurements.
• Measured TPC values showed good agreement and reliability with values calculated using the derived equations.

Conclusions:

• TPC values obtained using different methods and standards are strongly correlated.
• The developed equations enable reliable estimation of TPC values across different assays.
• This suggests interchangeability of TPC data obtained by various methods when appropriate conversion equations are applied.