No False Hemoccult Reaction with Ranitidine

To the Editor: The Hemoccult slide test (Smith Kline Diagnostics) is often used to test for occult blood in gastric aspirates. Results from this test have been shown to be falsely negative at low pHs found in gastric fluid^1,2 or falsely positive as a result of oral cimetidine administration.³ Cimetidine's interference with the Hemoccult test is thought to be a consequence of the tablet dye used in formulation.⁴ Since ranitidine is often used in the same clinical situations, we investigated whether ranitidine or any constituents in the tablet formulation might also alter the results of the Hemoccult slide test. Gastric-aspirate.