24-48 hours after setup at PeaceHealth Laboratories’ reference lab.
Specimen Collection Details
Random stool in a plastic container.
Freeze immediately. A non-frozen specimen may produce a false-positive result.
48 hours frozen. Unstable ambient or refrigerated.
5 gm stool.
1 gm stool.
Frozen on dry ice.
Phenolphthalein is a cathartic that has its greatest effect on the colon. It usually does not act <6 hours after oral administration and, therefore, is taken at bedtime to produce the laxative effect the next morning. Up to 15% is absorbed and the remainder is excreted in the feces. The absorbed portion is largely eliminated by the kidneys with a small amount excreted in bile. Useful for detection of laxative abuse. A homogenized stool is preferred. Thirty-three percent KOH is added; and if phenolphthalein is present, the stool turns red or pink. The test is reported as present or not detected.