Development and evaluation of a direct immunofluorimetric assay for urinary growth hormone.

We describe a two-site immunofluorimetric assay for urinary growth hormone that is resistant to interference from a wide range of urinary constituents and therefore eliminates the need for sample pre-treatment. A microtitre plate format is used with specific orientation of capture antibody on a polystyrene surface carrying a hydrazide group. Europium-labelled F(ab)2 is the fluorophore and time-resolved fluorimetry with co-fluorescence enhancement the signal detection system. Inter-assay precision was 11.3% at 5.2 ng/L and 10.3% at 44.3 ng/L, minimum detection limit (22% coefficient of variation, CV) was < 1.0 ng/L, working range (< 10% CV) was 0-100 ng/L and quantitative recovery and good parallelism were demonstrated. This convenient and sensitive assay is suitable for the routine measurement of human growth hormone (hGH) in urine.