Abstract: Marker compounds indicative of variations in physiological conditions, genetic defects or disease states have been found to be present in apocrine sweat and, in many conditions, these markers are present in apocrine sweat in elevated levels when compared to blood. These markers are collected and/or detected in apocrine sweat and used as an indicator that a disease state or particular physiological condition exists. A skin patch, wipe or other collection means is used to collect apocrine sweat. The apocrine sweat is then used to indicate the existence of a disease state or changing physiological condition by the presence of specific marker compounds.