Simple method for correcting total protein in plasma for actual fibrinogen content

Area of Science:

• Clinical Chemistry
• Biochemistry

Background:

• Plasma is increasingly used for routine chemistry analyses due to its advantages over serum.
• A key challenge is the inclusive measurement of fibrinogen in plasma total protein assays, potentially affecting interpretation.
• Fibrinogen is a significant protein fraction in plasma.

Purpose of the Study:

• To investigate subtracting fibrinogen from plasma total protein to improve assay accuracy.
• To maintain the clinical significance of total protein assays when using plasma.

Main Methods:

• Correlating serum total protein with uncorrected plasma total protein.
• Correlating serum total protein with plasma total protein corrected for fibrinogen levels.
• Measuring fibrinogen concentrations across different patient populations.

Main Results:

• Excellent correlation between serum and plasma total protein (r = 0.969).
• Correcting plasma total protein for fibrinogen significantly reduced the intercept (r = 0.985), improving correlation.
• Mean fibrinogen concentrations varied by group, from 2.5 g/L in blood donors to 6.6 g/L in patients with elevated C-reactive protein.

Conclusions:

• Plasma total protein results should be corrected for fibrinogen to enhance accuracy.
• This correction method maintains the clinical utility of total protein assays.
• Fibrinogen levels differ significantly across various clinical states.