The effect of sulfobromophthalein on serum PBI, BEI and thyroxine-iodine

Abstract The presence of organically bound iodine in some sulfobromophthalein (BSP) solutions is capable of falsely elevating the serum PBI level in direct proportion to the amount of BSP retained in the serum. There is a significant variation in the amount of this contaminant present in different lots of BSP from the same manufacturer. Depending on the severity of BSP retention and the level of organic iodine in the BSP solution used, the serum PBI may be falsely elevated for several hours to several days following injection. Neither the serum BEI nor the column Chromatographic procedure for thyroxine-iodine were found to be affected by BSP. It is suggested that the contamination of BSP with organic iodine be considered as the cause of unexplained elevations in serum PBI following the use of this liver function test.