A new ELISA method for the rapid quantification of Tamm-Horsfall protein in urine

The authors present a simplified enzyme-linked immunosorbent assay (ELISA) technique for the quantitative measurement of urinary Tamm-Horsfall protein (THP). Microtiter plates are coated with THP and urine samples at various dilutions without the need for a capture antibody. The bound glycoprotein is then incubated with a monoclonal anti-THP antibody and an alkaline phosphatase conjugated anti-IgG antibody. The assay was validated and gave reproducible results over a wide range of absorbance values. The sensitivity of the assay for THP was 2-5 micrograms/L, the coefficient of variation between assays 7.5%, and the day-to-day variability 11.1% for THP concentrations between 6.25 and 200 micrograms/L. THP excretion was assayed in five volunteers over five days comparing THP concentration in spot urines and in 24-hour urine collections.