Influence of aspirin and ethanol on fecal blood levels as determined by using the HemoQuant assay.

We sought to determine the short-term effects of use of aspirin and ethanol on fecal occult blood levels measured with the HemoQuant assay. A factorial design was used to study 68 healthy volunteers randomized to receive various doses of aspirin, ethanol, or a combination of both for either 1 or 3 days. Fecal hemoglobin concentrations were measured before and after drug ingestions. Moderate quantities of ethanol (300 ml of 5% or 30 ml of 50% three times nightly) did not cause significant fecal blood elevation unless aspirin was administered concomitantly (P = 0.05). High-dose aspirin alone, 975 mg three times daily, induced abnormal blood loss (P less than 0.01). The highest HemoQuant levels were usually noted after concomitant administration of aspirin and ethanol at maximal doses for 3 days (P less than 0.005), some HemoQuant levels approaching 5 times the normal value. We conclude that, in a short-term analysis, social consumption of ethanol is unlikely to interfere with fecal blood testing but therapeutic doses of aspirin will.