Indican excretion in the elderly.

It has been suggested that up to a half of elderly hospitalized patients excrete an abnormally high concentration of indican compared with young individuals. Thus, the commonly used colorimetric qualitative test for urinary indican excess may be invalid in the aged. However, of 21 young control subjects, 18 healthy elderly subjects, and 23 disabled, elderly, long-stay patients, no individual had levels of indican detectable by the standard colorimetric qualitative test. The use of a quantitative assay demonstrated that urinary indican concentration is similar in young and elderly individuals. A diurnal variation in urinary indican concentration was discovered which may affect the interpretation of the qualitative test.