A highly sensitive and reproducible immunoradiometric assay for total human renin using monoclonal antibodies, iodogen labelling and polystyrene star tubes.

A two-site immunoradiometric assay for total renin concentration in human plasma is described. A new type of polystyrene tubes with a special bottom geometry, so-called Star Tubes were used. The lower limit of detection was 2 microIU per ml and the working range from 2 to 2000 microIU per ml. The variation for duplicate determinations on standards and plasma samples was 2.7% and the day to day variation was 4.8%. No significant interferences or cross reactivities were identified. EDTA-plasma was analyzed after dilution with a phosphate buffer. Plasma samples from different patient categories were analyzed. The results were compared with those obtained by our substrate enrichment method after acid activation of the samples had taken place. A linear correlation (r = 0.990) between the results obtained with the two methods was found.