Enzyme-linked immunosorbent assay for free thyroxin in human serum

Area of Science:

• Clinical Chemistry
• Immunoassays
• Endocrinology

Background:

• Accurate measurement of free thyroxine (FT4) is crucial for diagnosing thyroid disorders.
• Existing methods for FT4 determination may be complex or require specialized reagents.

Purpose of the Study:

• To develop and validate a simple, accessible enzyme-linked immunosorbent assay (ELISA) for quantifying free thyroxine (FT4) in human serum.
• To establish the assay's performance characteristics, including working range, turnaround time, and precision.

Main Methods:

• Utilized microtiter plates for the enzyme-linked immunosorbent assay (ELISA) format.
• Employed only commercially available chemicals and reagents, including antiserum.
• Validated the assay against a radioimmunoassay method using 150 serum samples.

Main Results:

• The developed ELISA demonstrated a working range of 1 to 60 ng/L for FT4.
• Assay turnaround time was approximately 4 hours.
• Within-run coefficients of variation (CV) were <5%, and between-run CVs were 10-11%.
• Correlation with radioimmunoassay yielded a coefficient (r) of 0.922.

Conclusions:

• The described ELISA provides a simple, rapid, and reliable method for FT4 measurement in serum.
• The assay's reliance on commercially available reagents enhances its accessibility for clinical laboratories.
• The method shows good agreement with established radioimmunoassay techniques.