Radioimmunoassay for urinary albumin

Area of Science:

• Nephrology
• Clinical Chemistry
• Immunology

Background:

• Urinary albumin (Ualb) is a key indicator of kidney function.
• Accurate measurement of Ualb is essential for diagnosing and monitoring renal diseases.
• Existing methods may lack the required sensitivity or precision.

Purpose of the Study:

• To develop and validate a rapid, sensitive, and precise radioimmunoassay for quantifying urinary albumin (Ualb).
• To establish reference ranges for Ualb and albumin clearance (Calb) in normal individuals.
• To evaluate the utility of the Ualb assay in patients post-renal homograft.

Main Methods:

• Radioimmunoassay utilizing 125I-labeled human albumin and a monospecific rabbit antiserum.
• Double-antibody technique for phase separation.
• Assay validation for linearity, sensitivity, and precision (coefficient of variation).

Main Results:

• The assay demonstrated linearity from 15.6-10000 ng, with a sensitivity limit of 16 ng.
• The coefficient of assay variation was 4.8% at different concentrations.
• Normal Ualb ranged from 2.2–12.6 mg/24h; Calb ranged from 1.8 x 10(-5)–19.6 x 10(-5) ml/min.
• Post-renal homograft, Ualb and Calb levels varied widely and correlated with rejection severity.

Conclusions:

• The developed radioimmunoassay is a rapid, sensitive, and precise method for Ualb measurement.
• The assay is suitable for clinical application, including monitoring renal homograft status.
• Increased Ualb and Calb levels effectively indicate the severity of renal homograft rejection.