Twenty-two of 24 healthy subjects showed an elevation of sulfobromophthalein (BSP) levels following ingestion of iopanoic acid (Telepaque); six of the readings were abnormal. Our data suggest that there is competition for excretion of iopanoic acid and BSP, which results in false elevation of BSP readings. To avoid errors in the diagnosis of liver disease, it is recommended that the BSP test and cholecystography not be performed concomitantly.
Meyer RR. Effect of Iopanoic Acid on the Sulfobromophthalein Test. JAMA. 1965;194(4):343-344. doi:10.1001/jama.1965.03090170021007