Filling in the gaps with non-standard body fluids

Area of Science:

• Clinical Chemistry
• Laboratory Medicine
• Analytical Biochemistry

Background:

• Manufacturers often do not validate body fluid assays beyond serum, plasma, or urine.
• Analysis of non-standard body fluids is crucial for accurate clinical diagnosis and patient management.
• Laboratories depend on published literature for guidance on validating and implementing tests for these fluids.

Purpose of the Study:

• To determine the clinical reportable range for 11 analytes in non-standard body fluids using a data-driven approach.
• To evaluate the performance of a total bilirubin assay in non-standard fluids.
• To assess the impact of hemolysis, icterus, and lipemia interferences on these analytes.

Main Methods:

• Utilized historical data from Beckman Coulter DxC800 to optimize reportable ranges for 11 analytes on the AU680 analyzer.
• Conducted interference studies by spiking hemolysate, bilirubin, and Intralipid® into abnormal serous fluids.
• Evaluated precision, accuracy, linearity, and stability of the total bilirubin assay in non-standard fluids.

Main Results:

• Assays required varying degrees of dilution (none, onboard, or manual) for reporting numeric results.
• The AU680 total bilirubin assay demonstrated suitability for non-standard fluid testing.
• Interference from lipemia affected 1 analyte, icterus affected 3, and hemolysis affected 5 out of 11 analytes.

Conclusions:

• Chemistry analytes analyzed on the AU680 exhibit acceptable analytical performance for non-standard body fluids.
• Common endogenous interferences (lipemia, icterus, hemolysis) were identified.
• Flagging rules based on interference indices were developed to enhance clinical interpretation of results.