Abstract: A RADIOIMMUNOASSAY KIT FOR URINARY α_1－MICROGLOBULINLiu Yibing；Han Shiquan；Chen Jian；Wang Yanzhen（China Institute of Atomic Energy，P．O．Box 275，Beijing 102413）ABSTRACT α_1－microglobulin （α_1－MG）was　isolated and purified from the urine of patients with kindey translation by ammonium sulfate precipitation and chromatography on sephadex G－75，Con A－sepharose 4Band DEAE－cellous 32．Antiserum were raised by immunizing rabbits．The titers of antiserum were 1：1000－1：3500 and affinity constant was 3．45×10~9l／mol．The cross reactions with β_2－MG，Alband IgG were less than 0．003％．Urinary α_1－MG RIA kit was developed．The standard range was 25to 800 ng／ml and the mean of recoveries was 112％Intra- and Inter－assay coefficient of variationwere 2．5％－3．3％and 2．4％－3．8％respoctively．The normal value was 5．86±4．50μg／ml．Key words α_1－microglobulin kindey function radioimmunoassay