obsolete test for liver function (hepatic excretory capacity) in which a known amount of dye, usually 5 mg/kg of body weight, is injected intravenously; subsequently (usually after 45 minutes elapsed time), the amount of dye remaining in the serum is measured; a concentration of 0.4 mg or less of bromsulphalein per 100 mL of serum or less than 4% of the injected dye is considered normal; bromsulphalein retention may follow decreased hepatic blood flow or biliary obstruction as well as hepatic cell damage. SYN: BSP test.